Android Kit Kat - Printing Framework
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The Android printing framework allows apps to print content to various printers. PrintManager is used to initiate print jobs by providing a PrintDocumentAdapter, which handles rendering the document content onto pages. The adapter must implement callbacks like onLayout to determine the page count and onWrite to render each page. Custom adapters can draw directly onto page canvases. PrintHelper provides a simplified way to print bitmaps.
![ApiDemos
[sdk]/sampes/android-19/legacy/ApiDemos](https://image.slidesharecdn.com/androidkitkat-printingframework-140204141644-phpapp01/85/Android-Kit-Kat-Printing-Framework-5-320.jpg)
![Custom Print Adapters
onWrite()
public void onWrite(
final PageRange[] pages,
final ParcelFileDescriptor destination,
final CancellationSignal cancellationSignal,
final WriteResultCallback callback) {
CONTRACT
onWriteFinished(PageRange[])
}
onWriteCancelled()
onWriteFailed(CharSequence)](https://image.slidesharecdn.com/androidkitkat-printingframework-140204141644-phpapp01/85/Android-Kit-Kat-Printing-Framework-13-320.jpg)
![Custom Print Adapters
onWrite()
Start writing a page:
Page page = document.startPage(pageNumber);
Draw onto the page canvas:
page.getCanvas();
Note that elements are specified in points (1/72 inch)
Finish writing the page:
document.finishPage(page);
Inform WriteResultCallback of the PageRange[] printed](https://image.slidesharecdn.com/androidkitkat-printingframework-140204141644-phpapp01/85/Android-Kit-Kat-Printing-Framework-14-320.jpg)
Android Kit Kat - Printing Framework
- 2. The gist of it
- 3. The gist of it PrintManager
- 4. Prerequisites SDK platform 19 SDK build-tools 19 or later Something to print with A Google Cloud Print Ready printer A printer shared through Google Cloud Print Print to PDF
- 6. PrintManager PrintManager printManager = (PrintManager) context.getSystemService(Context.PRINT_SERVICE); PrintJob printJob = printManager.print( printJobName, documentAdapter, attributes); Name for the print job (shown to the user) Default print job attributes Adapter that emits the document
- 7. PrintDocumentAdapter Web pages PrintDocumentAdapter documentAdapter = // Directly from an existing WebView webView.createPrintDocumentAdapter();
- 8. PrintDocumentAdapter Web pages // Create a WebView and start printing when its ready WebView webView = new WebView(context); webView.setWebViewClient(new WebViewClient() { @Override public void onPageFinished( WebView webView, String url) { // Print to it as before PrintDocumentAdapter documentAdapter = webView.createPrintDocumentAdapter(); } }); webView.loadUrl(url);
- 9. PrintDocumentAdapter Custom documents PrintDocumentAdapter documentAdapter = // Define a custom print adapter new MyPrintDocumentAdapter(context);
- 10. Custom Print Adapters Events: onStart() Print process has begun. onLayout() A print setting has changed and the layout of the pages needs to be computed. Must return expected number of pages. onWrite() Render printed pages into a file. onFinish() Print process has ended.
- 11. Custom Print Adapters onLayout() public void onLayout( final PrintAttributes oldAttributes, final PrintAttributes newAttributes, final CancellationSignal cancellationSignal, final LayoutResultCallback callback, final Bundle metadata) { CONTRACT onLayoutFinished( PrintDocumentInfo, boolean) } onLayoutCancelled() onLayoutFailed(CharSequence)
- 12. Custom Print Adapters onLayout() Create a document for printing: PrintedPdfDocument document = new PrintedPdfDocument(context, newAttributes); Compute the number of pages using PrintAttributes Return print information to the print framework: PrintDocumentInfo info = new PrintDocumentInfo .Builder("print_output.pdf") .setContentType( PrintDocumentInfo.CONTENT_TYPE_DOCUMENT) .setPageCount(pages); .build(); callback.onLayoutFinished(info, true); Wait for the print framework to invoke onWrite()
- 13. Custom Print Adapters onWrite() public void onWrite( final PageRange[] pages, final ParcelFileDescriptor destination, final CancellationSignal cancellationSignal, final WriteResultCallback callback) { CONTRACT onWriteFinished(PageRange[]) } onWriteCancelled() onWriteFailed(CharSequence)
- 14. Custom Print Adapters onWrite() Start writing a page: Page page = document.startPage(pageNumber); Draw onto the page canvas: page.getCanvas(); Note that elements are specified in points (1/72 inch) Finish writing the page: document.finishPage(page); Inform WriteResultCallback of the PageRange[] printed
- 15. Custom Print Adapters Caveats If you need a screen context, remember that the printer and screen densities differ! Obtain the printer density: printerDensity = Math.max( newAttributes.getResolution().getHorizontalDpi(), newAttributes.getResolution().getVerticalDpi()); Create a new Context to cope with a different Configuration: Configuration configuration = new Configuration(); configuration.densityDpi = printerDensity; printContext = createConfigurationContext( configuration); Use this context for creating new views: View view = new LinearLayout(printContext); view.draw(page.getCanvas());
- 16. PrintHelper PrintHelper printHelper = new PrintHelper(context); // Instruct how the content should scale printHelper.setScaleMode(PrintHelper.SCALE_MODE_FIT); // Get the bitmap for the ImageView's drawable Bitmap bitmap = ((BitmapDrawable) mImageView.getDrawable()).getBitmap(); // Print the bitmap printHelper.printBitmap("Print Bitmap", bitmap);
- 17. Happy printing!