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Let's write a PDF file

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Ange Albertini

The document provides a step-by-step guide to writing a basic "Hello World" PDF file. It explains the overall PDF file structure and key elements like the file body, cross-reference table, trailer, and objects. Objects are used to define things like the catalog, pages, and a single page. The guide demonstrates creating three objects - one for the catalog that refers to a pages object, which in turn refers to a page object defining a single page.

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Let’s write a PDF file A simple walk-through to learn the basics of the PDF format (at your rhythm) PDF = Portable Document Format r2
Ange Albertini reverse engineering & visual documentation @angealbertini ange@corkami.com http://www.corkami.com
Goal: write a “Hello World” in PDF
PDF is text-based, with some binary in specific cases. But not in this example, so just open a text editor.
Statements are separated by white space. (any extra white space is ignored) Any of these: 0x00 Null 0x0C Form Feed 0x09 Tab 0x0D Carriage Return 0x0A Line feed 0x20 Space (yes, you can mix EOL style :( )
Delimiters don’t require white space before. ( ) < > [ ] { } /
_ Let’s start!
%PDF-_ A PDF starts with a %PDF-? signature followed by a version number. 1.0 <= version number <= 1.7 (it doesn’t really matter here)
%PDF-1.3 _ Ok, we have a valid signature ☺
%PDF-1.3 %_ A comment starts with % until the end of the line.
%PDF-1.3 %file body _ After the signature, comes the file body. (we’ll see about it later)
%PDF-1.3 %file body xref _ After the file body, comes the cross reference table. It starts with the xref keyword, on a separated line.
%PDF-1.3 %file body xref %xref table here _ After the xref keyword, comes the actual table. (we’ll see about it later)
%PDF-1.3 %file body xref %xref table here trailer_ After the table, comes the trailer... It starts with a trailer keyword.
%PDF-1.3 %file body xref %xref table here trailer %trailer contents _ (we’ll see that later too…) ...and its contents.
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref _ (with startxref) Then, a pointer to the xref table...
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer _ (later, too...)
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF_ ...an %%EOF marker. Lastly, to mark the end of the file...
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Easy ;) That’s the overall layout of a PDF document!
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Now, we just need to fill in the rest :)
Study time
Def: name objects A.k.a. “strings starting with a slash”
/Name A slash, then an alphanumeric string (no whitespace)
Case sensitive /Name != /name Names with incorrect case are just ignored (no error is triggered)
Def: dictionary object Sequence of keys and values (no delimiter in between) enclosed in << and >> sets each key to value
Syntax << key value key value [key value]*… >>
Keys are always name objects << /Index 1>> sets /Index to 1 << Index 1 >> is invalid (the key is not a name)
Dictionaries can have any length << /Index 1 /Count /Whatever >> sets /Index to 1 and /Count to /Whatever
Extra white space is ignored(as usual) << /Index 1 /Count /Whatever >> is equivalent to << /Index 1 /Count /Whatever >>
Dictionaries can be nested. << /MyDict << >> >> sets /MyDict to << >> (empty dictionary)
White space before delimiters is not required. << /Index 1 /MyDict << >> >> equivalent to <</Index 1/MyDict<<>>>>
Def: indirect object an object number (>0), a generation number (0*) the obj keyword the object content the endobj keyword * 99% of the time
Example 1 0 obj 3 endobj is object #1, generation 0, containing “3”
Def: object reference object number, object generation, R number number R ex: 1 0 R
Object reference Refers to an indirect object as a value ex: << /Root 1 0 R >> refers to object number 1 generation 0 as the /Root
Used only as values in a dictionary << /Root 1 0 R >> is OK. << 1 0 R /Catalog>> isn’t.
Be careful with the syntax! “1 0 3” is a sequence of 3 numbers 1 0 3 “1 0 R” is a single reference to an object number 1 generation 0
Def: file body sequence of indirect objects object order doesn’t matter
Example 1 0 obj 3 endobj 2 0 obj << /Index 1 >> endobj defines 2 objects with different contents
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Remember this?
A PDF document is defined by a tree of objects.
%PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Now, let’s start!
%PDF-1.3 %file body xref %xref table here trailer << _ >> startxref %xref pointer %%EOF The trailer is a dictionary.
%PDF-1.3 %file body xref %xref table here trailer << /Root_ >> startxref %xref pointer %%EOF It defines a /Root name...
%PDF-1.3 %file body xref %xref table here trailer << /Root 1 0 R_>> startxref %xref pointer %%EOF ...that refers to an object...
%PDF-1.3 %file body xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF (like all the the other objects) ...that will be in the file body.
Recap: the trailer is a dictionary that refers to a root object.
%PDF-1.3 _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s create our first object...
%PDF-1.3 1 0 obj _ endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …(with the standard object declaration)...
%PDF-1.3 1 0 obj << _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF (like most objects) ...that contains a dictionary.
%PDF-1.3 1 0 obj << /Type_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and its /Type is...
%PDF-1.3 1 0 obj << /Type /Catalog_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...defined as /Catalog...
%PDF-1.3 1 0 obj << /Type /Catalog _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF the /Root object also refers to the page tree...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...via a /Pages name...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...that refers to another object...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which we’ll create.
Recap: object 1 is a catalog, and refers to a Pages object.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s create object 2.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj _ endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The usual declaration.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF It’s a dictionary too.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The pages’ object /Type has to be defined as … /Pages ☺
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF This object defines its children via /Kids...
Def: array enclosed in [ ] values separated by whitespace ex: [1 2 3 4] is an array of 4 integers 1 2 3 4
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ _ ] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which is an array...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R_] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … of references to each page object.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last step...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...the number of kids has to be set in /Count...
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and now object 2 is complete!
Recap: object 2 is /Pages; it defines Kids + Count (pages of the document).
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj _ We can add our only Kid...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj _ endobj …(a single page)...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << _ >> endobj … a dictionary...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type_ >> endobj … defining a /Type...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page_ >> endobj … as /Page.
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent_ >> endobj This grateful kid properly recognizes its own parent...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R_>> endobj … as you would expect ☺
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R _ >> endobj Our page requires resources.
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources_ >> endobj Let’s add them...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << _ >> >> endobj ...as a dictionary:
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font_ >> >> endobj In this case, fonts...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj ...as a dictionary.
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj We define one font...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1_ >> >> >> endobj ...by giving it a name...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << _ >> >> >> >> endobj ...and setting its parameters:
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type_ >> >> >> >> endobj its type is ...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font_ >> >> >> >> endobj … font ☺
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype_ >> >> >> >> endobj Its font type is...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1_ >> >> >> >> endobj …(Adobe) Type1...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont_>> >> >> >> endobj ...and its name is...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial_>> >> >> >> endobj .../Arial.
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> _ >> endobj One thing is missing in our page...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents_ >> endobj The actual page contents...
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R_ >> endobj … as a reference to another object.
xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj That’s all for our page object.
Recap: object 3 defines a /Page, its /Parent, /Resources (fonts) and its /Contents is in another object.(thank you Mario!)
Study time
Def: stream objects So far, everything is text. How do you store binary data (images,...) ?
1 0 obj … endobj Stream objects are objects. They start and they end like any other object: Ex: .
Stream objects contain a stream. between stream and endstream keywords 1 0 obj stream <stream content> endstream endobj
Streams can contain anything Yes, really! Even binary, other file formats... (except the endstream keyword)
Stream parameters are stored before the stream. a dictionary after obj, before stream required: stream length optional: compression algorithm, etc…
1 0 obj << /Length 10 >> stream 0123456789 endstream endobj Example
_ %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj _ endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We create a /Content object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj stream _ endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...that is a stream object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
Study time
Page contents syntax parameters sequence then operator ex: param1 param2 operator
4 0 obj stream _ endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj Text objects are delimited by BT and ET... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj stream BT _ ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(BeginText & EndText). xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj stream BT Tf_ ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We need to set a font, with Tf. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj stream BT _ Tf ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj It takes 2 parameters: a font name... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj stream BT /F1_ Tf ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(from the page’s resources)... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100_Tf ET endstream endobj ...and a font size. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ ET endstream endobj We move the cursor... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf Td_ ET endstream endobj ...with the Td operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ Td ET endstream endobj ...that takes 2 parameters... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf 10 400_Td ET endstream endobj ...x and y coordinates. (default page size: 612x792) xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
Study time
Def: literal strings enclosed in parentheses Ex: (Hi Mum)
Can contain parentheses (Hello() World((()
Can contain white space ( Hello World ! )
Standard escaping is supported (Hello World rn)
Escaping is in octal (Hell157 World)
4 0 obj stream BT /F1 100 Tf 10 400 Td _ ET endstream endobj Showing a text string... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td Tj_ ET endstream endobj ...is done with the Tj operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td _ Tj ET endstream endobj ...that takes a single parameter... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td (_) Tj ET endstream endobj ...a literal string. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World_) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our contents stream is complete... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj _ stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last thing... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj << _ >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...we need to set its parameters... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj << /Length_ >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … the stream length... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj << /Length 44_>> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …including white space (new lines characters…). %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our stream parameters are finished... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so our page contents object is finished. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
Recap: obj 4 is a stream object with a set length, defining the page’s contents: declare text, set a font and size, move cursor, display text.
The whole document is defined. We need to polish the structure.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our PDF defines 4 objects, starting at index 1...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but PDFs always have an object 0, that is null...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so 5 objects, starting at 0.
Warning: offsets & EOLs We have to define offsets, which are affected by the EOL conventions: 1 char under Linux/Mac, 2 under Windows. (I use 1 char newlines character here)
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s edit the XREF table!
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The next line defines the starting index...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and the number of objects.
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, one line per object...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...following the xxxxxxxxxx yyyyy a format (10 digits, 5 digits, 1 letter).
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The first parameter is the offset (in decimal) of the object...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...(for the null object, it’s 0).
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, the generation number (that is almost always 0)...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but for object 0, it’s 65535.
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, a letter, to tell if this entry is free (f) or in use (n).
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Lastly, each line should take 20 bytes, including EOL...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so add a trailing space.
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Next line (the first real object)...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …object offset, in decimal...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …generation number...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and declare the object index in use (n)...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and the trailing space
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Do the same with the other objects...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 00000 n 00000 n 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …knowing that all lines will end with “ 00000 n ”,...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...set all offsets.
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The cross-reference table is finished.
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref _ %%EOF We set the startxref pointer...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364_ %%EOF ...as xref’s offset, in decimal (no prepending 0s).
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364 %%EOF
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R _ >> startxref 364 %%EOF We also need to update the trailer dictionary...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size_ >> startxref 364 %%EOF ...with the number of objects...
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5_>> startxref 364 %%EOF … in the PDF (including object 0).
4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF Our PDF is now complete.
%PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF
Disclaimer: this is a minimal PDF. Most PDF documents are much bigger, and contain many more elements. Our PDF: 528 bytes 4 objects text only A standard generated “Hello World”: 15 kiloBytes 20 objects text and binary (embedded fonts…)
No need to type them yourself! Hint: use “mutool clean” to fix offsets and lengths. http://www.mupdf.com/
⇒ mutool version Slightly different content, but same rendering. %PDF-1.3 %%μῦ 1 0 obj <</Type/Catalog/Pages 2 0 R>> endobj 2 0 obj <</Type/Pages/Kids[3 0 R]/Count 1>> endobj 3 0 obj <</Type/Page/Parent 2 0 R/Resources 5 0 R/Contents 4 0 R>> endobj 4 0 obj <</Length 49>> stream q BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET Q endstream endobj 5 0 obj <</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Arial>>>>>> endobj xref 0 6 0000000000 65536 f 0000000018 00000 n 0000000064 00000 n 0000000116 00000 n 0000000191 00000 n 0000000288 00000 n trailer <</Size 6/Root 1 0 R>> startxref 364 %%EOF
Hint: you can directly extract the PDF sources. use “pdftotext --layout” on the slide deck http://www.foolabs.com/xpdf/home.html
One more thing... This one is important for self study.
Def: stream filters streams can be encoded and/or compressed algorithms can be cascaded ex: compression, then ASCII encoding
New stream parameter: /Filter ex: encode the stream in ASCII 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 24 /Filter /ASCIIHexDecode>> stream 48656C6C6F20576F726C6421 endstream endobj ⇔
Ex: compression (deflate = ZIP compression) 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 20 /Filter /FlateDecode>> stream x£¾H═╔╔¤/╩IQ♦ ∟I♦> endstream endobj ⇔
Filters can be cascaded. Ex: compressed, then encoded in ASCII 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 40 /Filter [/ASCIIHexDecode /FlateDecode] >> stream 789CF348CDC9C95708CF2FCA495104001C49043E endstream endobj ⇔
Hint: “mutool clean -d” to remove any stream filter. (if you want to explore PDFs by yourself) http://www.mupdf.com/
Want more? pdf101.corkami.com
Questions? (you can download this poster at http://pics.corkami.com)
ACK @Doegox @ChrisJohnRiley @PDFKungFoo
To be continued...? https://leanpub.com/binaryisbeautiful
Let’s write a PDF file corkami.com @angealbertini Hail to the king, baby! r2

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Let's write a PDF file

  • 1. Let’s write a PDF file A simple walk-through to learn the basics of the PDF format (at your rhythm) PDF = Portable Document Format r2
  • 2. Ange Albertini reverse engineering & visual documentation @angealbertini [email protected] http://www.corkami.com
  • 3. Goal: write a “Hello World” in PDF
  • 4. PDF is text-based, with some binary in specific cases. But not in this example, so just open a text editor.
  • 5. Statements are separated by white space. (any extra white space is ignored) Any of these: 0x00 Null 0x0C Form Feed 0x09 Tab 0x0D Carriage Return 0x0A Line feed 0x20 Space (yes, you can mix EOL style :( )
  • 6. Delimiters don’t require white space before. ( ) < > [ ] { } /
  • 8. %PDF-_ A PDF starts with a %PDF-? signature followed by a version number. 1.0 <= version number <= 1.7 (it doesn’t really matter here)
  • 9. %PDF-1.3 _ Ok, we have a valid signature ☺
  • 10. %PDF-1.3 %_ A comment starts with % until the end of the line.
  • 11. %PDF-1.3 %file body _ After the signature, comes the file body. (we’ll see about it later)
  • 12. %PDF-1.3 %file body xref _ After the file body, comes the cross reference table. It starts with the xref keyword, on a separated line.
  • 13. %PDF-1.3 %file body xref %xref table here _ After the xref keyword, comes the actual table. (we’ll see about it later)
  • 14. %PDF-1.3 %file body xref %xref table here trailer_ After the table, comes the trailer... It starts with a trailer keyword.
  • 15. %PDF-1.3 %file body xref %xref table here trailer %trailer contents _ (we’ll see that later too…) ...and its contents.
  • 16. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref _ (with startxref) Then, a pointer to the xref table...
  • 17. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer _ (later, too...)
  • 18. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF_ ...an %%EOF marker. Lastly, to mark the end of the file...
  • 19. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Easy ;) That’s the overall layout of a PDF document!
  • 20. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Now, we just need to fill in the rest :)
  • 22. Def: name objects A.k.a. “strings starting with a slash”
  • 23. /Name A slash, then an alphanumeric string (no whitespace)
  • 24. Case sensitive /Name != /name Names with incorrect case are just ignored (no error is triggered)
  • 25. Def: dictionary object Sequence of keys and values (no delimiter in between) enclosed in << and >> sets each key to value
  • 26. Syntax << key value key value [key value]*… >>
  • 27. Keys are always name objects << /Index 1>> sets /Index to 1 << Index 1 >> is invalid (the key is not a name)
  • 28. Dictionaries can have any length << /Index 1 /Count /Whatever >> sets /Index to 1 and /Count to /Whatever
  • 29. Extra white space is ignored(as usual) << /Index 1 /Count /Whatever >> is equivalent to << /Index 1 /Count /Whatever >>
  • 30. Dictionaries can be nested. << /MyDict << >> >> sets /MyDict to << >> (empty dictionary)
  • 31. White space before delimiters is not required. << /Index 1 /MyDict << >> >> equivalent to <</Index 1/MyDict<<>>>>
  • 32. Def: indirect object an object number (>0), a generation number (0*) the obj keyword the object content the endobj keyword * 99% of the time
  • 33. Example 1 0 obj 3 endobj is object #1, generation 0, containing “3”
  • 34. Def: object reference object number, object generation, R number number R ex: 1 0 R
  • 35. Object reference Refers to an indirect object as a value ex: << /Root 1 0 R >> refers to object number 1 generation 0 as the /Root
  • 36. Used only as values in a dictionary << /Root 1 0 R >> is OK. << 1 0 R /Catalog>> isn’t.
  • 37. Be careful with the syntax! “1 0 3” is a sequence of 3 numbers 1 0 3 “1 0 R” is a single reference to an object number 1 generation 0
  • 38. Def: file body sequence of indirect objects object order doesn’t matter
  • 39. Example 1 0 obj 3 endobj 2 0 obj << /Index 1 >> endobj defines 2 objects with different contents
  • 40. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Remember this?
  • 41. A PDF document is defined by a tree of objects.
  • 42. %PDF-1.3 %file body xref %xref table here trailer %trailer contents startxref %xref pointer %%EOF Now, let’s start!
  • 43. %PDF-1.3 %file body xref %xref table here trailer << _ >> startxref %xref pointer %%EOF The trailer is a dictionary.
  • 44. %PDF-1.3 %file body xref %xref table here trailer << /Root_ >> startxref %xref pointer %%EOF It defines a /Root name...
  • 45. %PDF-1.3 %file body xref %xref table here trailer << /Root 1 0 R_>> startxref %xref pointer %%EOF ...that refers to an object...
  • 46. %PDF-1.3 %file body xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF (like all the the other objects) ...that will be in the file body.
  • 47. Recap: the trailer is a dictionary that refers to a root object.
  • 48. %PDF-1.3 _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s create our first object...
  • 49. %PDF-1.3 1 0 obj _ endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …(with the standard object declaration)...
  • 50. %PDF-1.3 1 0 obj << _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF (like most objects) ...that contains a dictionary.
  • 51. %PDF-1.3 1 0 obj << /Type_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and its /Type is...
  • 52. %PDF-1.3 1 0 obj << /Type /Catalog_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...defined as /Catalog...
  • 53. %PDF-1.3 1 0 obj << /Type /Catalog _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF the /Root object also refers to the page tree...
  • 54. %PDF-1.3 1 0 obj << /Type /Catalog /Pages_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...via a /Pages name...
  • 55. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...that refers to another object...
  • 56. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which we’ll create.
  • 57. Recap: object 1 is a catalog, and refers to a Pages object.
  • 58. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s create object 2.
  • 59. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj _ endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The usual declaration.
  • 60. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF It’s a dictionary too.
  • 61. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The pages’ object /Type has to be defined as … /Pages ☺
  • 62. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF This object defines its children via /Kids...
  • 63. Def: array enclosed in [ ] values separated by whitespace ex: [1 2 3 4] is an array of 4 integers 1 2 3 4
  • 64. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ _ ] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which is an array...
  • 65. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R_] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … of references to each page object.
  • 66. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last step...
  • 67. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...the number of kids has to be set in /Count...
  • 68. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and now object 2 is complete!
  • 69. Recap: object 2 is /Pages; it defines Kids + Count (pages of the document).
  • 70. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj _ We can add our only Kid...
  • 71. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj _ endobj …(a single page)...
  • 72. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << _ >> endobj … a dictionary...
  • 73. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type_ >> endobj … defining a /Type...
  • 74. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page_ >> endobj … as /Page.
  • 75. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent_ >> endobj This grateful kid properly recognizes its own parent...
  • 76. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R_>> endobj … as you would expect ☺
  • 77. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R _ >> endobj Our page requires resources.
  • 78. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources_ >> endobj Let’s add them...
  • 79. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << _ >> >> endobj ...as a dictionary:
  • 80. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font_ >> >> endobj In this case, fonts...
  • 81. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj ...as a dictionary.
  • 82. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj We define one font...
  • 83. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1_ >> >> >> endobj ...by giving it a name...
  • 84. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << _ >> >> >> >> endobj ...and setting its parameters:
  • 85. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type_ >> >> >> >> endobj its type is ...
  • 86. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font_ >> >> >> >> endobj … font ☺
  • 87. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype_ >> >> >> >> endobj Its font type is...
  • 88. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1_ >> >> >> >> endobj …(Adobe) Type1...
  • 89. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont_>> >> >> >> endobj ...and its name is...
  • 90. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial_>> >> >> >> endobj .../Arial.
  • 91. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> _ >> endobj One thing is missing in our page...
  • 92. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents_ >> endobj The actual page contents...
  • 93. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R_ >> endobj … as a reference to another object.
  • 94. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj That’s all for our page object.
  • 95. Recap: object 3 defines a /Page, its /Parent, /Resources (fonts) and its /Contents is in another object.(thank you Mario!)
  • 97. Def: stream objects So far, everything is text. How do you store binary data (images,...) ?
  • 98. 1 0 obj … endobj Stream objects are objects. They start and they end like any other object: Ex: .
  • 99. Stream objects contain a stream. between stream and endstream keywords 1 0 obj stream <stream content> endstream endobj
  • 100. Streams can contain anything Yes, really! Even binary, other file formats... (except the endstream keyword)
  • 101. Stream parameters are stored before the stream. a dictionary after obj, before stream required: stream length optional: compression algorithm, etc…
  • 102. 1 0 obj << /Length 10 >> stream 0123456789 endstream endobj Example
  • 103. _ %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 104. 4 0 obj _ endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We create a /Content object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 105. 4 0 obj stream _ endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...that is a stream object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 107. Page contents syntax parameters sequence then operator ex: param1 param2 operator
  • 108. 4 0 obj stream _ endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj Text objects are delimited by BT and ET... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 109. 4 0 obj stream BT _ ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(BeginText & EndText). xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 110. 4 0 obj stream BT Tf_ ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We need to set a font, with Tf. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 111. 4 0 obj stream BT _ Tf ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj It takes 2 parameters: a font name... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 112. 4 0 obj stream BT /F1_ Tf ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(from the page’s resources)... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 113. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100_Tf ET endstream endobj ...and a font size. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 114. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ ET endstream endobj We move the cursor... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 115. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf Td_ ET endstream endobj ...with the Td operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 116. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ Td ET endstream endobj ...that takes 2 parameters... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 117. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf 10 400_Td ET endstream endobj ...x and y coordinates. (default page size: 612x792) xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 119. Def: literal strings enclosed in parentheses Ex: (Hi Mum)
  • 121. Can contain white space ( Hello World ! )
  • 123. Escaping is in octal (Hell157 World)
  • 124. 4 0 obj stream BT /F1 100 Tf 10 400 Td _ ET endstream endobj Showing a text string... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 125. 4 0 obj stream BT /F1 100 Tf 10 400 Td Tj_ ET endstream endobj ...is done with the Tj operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 126. 4 0 obj stream BT /F1 100 Tf 10 400 Td _ Tj ET endstream endobj ...that takes a single parameter... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 127. 4 0 obj stream BT /F1 100 Tf 10 400 Td (_) Tj ET endstream endobj ...a literal string. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 128. 4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World_) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 129. 4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our contents stream is complete... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 130. 4 0 obj stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 131. 4 0 obj _ stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last thing... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 132. 4 0 obj << _ >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...we need to set its parameters... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 133. 4 0 obj << /Length_ >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … the stream length... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 134. 4 0 obj << /Length 44_>> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …including white space (new lines characters…). %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 135. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our stream parameters are finished... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 136. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so our page contents object is finished. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj
  • 137. Recap: obj 4 is a stream object with a set length, defining the page’s contents: declare text, set a font and size, move cursor, display text.
  • 138. The whole document is defined. We need to polish the structure.
  • 139. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our PDF defines 4 objects, starting at index 1...
  • 140. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but PDFs always have an object 0, that is null...
  • 141. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so 5 objects, starting at 0.
  • 142. Warning: offsets & EOLs We have to define offsets, which are affected by the EOL conventions: 1 char under Linux/Mac, 2 under Windows. (I use 1 char newlines character here)
  • 143. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s edit the XREF table!
  • 144. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The next line defines the starting index...
  • 145. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and the number of objects.
  • 146. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, one line per object...
  • 147. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...following the xxxxxxxxxx yyyyy a format (10 digits, 5 digits, 1 letter).
  • 148. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The first parameter is the offset (in decimal) of the object...
  • 149. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...(for the null object, it’s 0).
  • 150. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, the generation number (that is almost always 0)...
  • 151. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but for object 0, it’s 65535.
  • 152. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, a letter, to tell if this entry is free (f) or in use (n).
  • 153. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Lastly, each line should take 20 bytes, including EOL...
  • 154. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so add a trailing space.
  • 155. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Next line (the first real object)...
  • 156. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …object offset, in decimal...
  • 157. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …generation number...
  • 158. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and declare the object index in use (n)...
  • 159. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and the trailing space
  • 160. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Do the same with the other objects...
  • 161. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 00000 n 00000 n 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …knowing that all lines will end with “ 00000 n ”,...
  • 162. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...set all offsets.
  • 163. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The cross-reference table is finished.
  • 164. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 165. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF
  • 166. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref _ %%EOF We set the startxref pointer...
  • 167. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364_ %%EOF ...as xref’s offset, in decimal (no prepending 0s).
  • 168. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364 %%EOF
  • 169. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R _ >> startxref 364 %%EOF We also need to update the trailer dictionary...
  • 170. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size_ >> startxref 364 %%EOF ...with the number of objects...
  • 171. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5_>> startxref 364 %%EOF … in the PDF (including object 0).
  • 172. 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF Our PDF is now complete.
  • 173. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF
  • 174. Disclaimer: this is a minimal PDF. Most PDF documents are much bigger, and contain many more elements. Our PDF: 528 bytes 4 objects text only A standard generated “Hello World”: 15 kiloBytes 20 objects text and binary (embedded fonts…)
  • 175. No need to type them yourself! Hint: use “mutool clean” to fix offsets and lengths. http://www.mupdf.com/
  • 176. ⇒ mutool version Slightly different content, but same rendering. %PDF-1.3 %%μῦ 1 0 obj <</Type/Catalog/Pages 2 0 R>> endobj 2 0 obj <</Type/Pages/Kids[3 0 R]/Count 1>> endobj 3 0 obj <</Type/Page/Parent 2 0 R/Resources 5 0 R/Contents 4 0 R>> endobj 4 0 obj <</Length 49>> stream q BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET Q endstream endobj 5 0 obj <</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Arial>>>>>> endobj xref 0 6 0000000000 65536 f 0000000018 00000 n 0000000064 00000 n 0000000116 00000 n 0000000191 00000 n 0000000288 00000 n trailer <</Size 6/Root 1 0 R>> startxref 364 %%EOF
  • 177. Hint: you can directly extract the PDF sources. use “pdftotext --layout” on the slide deck http://www.foolabs.com/xpdf/home.html
  • 178. One more thing... This one is important for self study.
  • 179. Def: stream filters streams can be encoded and/or compressed algorithms can be cascaded ex: compression, then ASCII encoding
  • 180. New stream parameter: /Filter ex: encode the stream in ASCII 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 24 /Filter /ASCIIHexDecode>> stream 48656C6C6F20576F726C6421 endstream endobj ⇔
  • 181. Ex: compression (deflate = ZIP compression) 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 20 /Filter /FlateDecode>> stream x£¾H═╔╔¤/╩IQ♦ ∟I♦> endstream endobj ⇔
  • 182. Filters can be cascaded. Ex: compressed, then encoded in ASCII 1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 40 /Filter [/ASCIIHexDecode /FlateDecode] >> stream 789CF348CDC9C95708CF2FCA495104001C49043E endstream endobj ⇔
  • 183. Hint: “mutool clean -d” to remove any stream filter. (if you want to explore PDFs by yourself) http://www.mupdf.com/
  • 185. Questions? (you can download this poster at http://pics.corkami.com)
  • 188. Let’s write a PDF file corkami.com @angealbertini Hail to the king, baby! r2