Removing use of Windows hooks for taking screenshots in IE.

This will fix the issue of taking full-page screenshots when using
the 32-bit IE driver on 64-bit Windows installations.

Author: jimevans

cpp/iedriver/CommandHandlers/ScreenshotCommandHandler.h

@@ -18,7 +18,6 @@
 #define WEBDRIVER_IE_SCREENSHOTCOMMANDHANDLER_H_
 
 #include "../Browser.h"
-#include "../HookProcessor.h"
 #include "../IECommandHandler.h"
 #include "../IECommandExecutor.h"
 #include "logging.h"
@@ -129,76 +128,56 @@ class ScreenshotCommandHandler : public IECommandHandler {
     LOG(DEBUG) << "Initial chrome sizes are (w, h): "
                << chrome_width << ", " << chrome_height;
 
-    // Technically, we could use a custom structure here, and save a
-    // few bytes, but RECT is already a well-known structure, and
-    // one that is included as part of the Windows SDK, so we'll
-    // leverage it.
-    RECT max_image_dimensions;
-    max_image_dimensions.left = 0;
-    max_image_dimensions.top = 0;
-    max_image_dimensions.right = document_info.width + chrome_width;
-    max_image_dimensions.bottom = document_info.height + chrome_height;
+    int target_window_width = document_info.width + chrome_width;
+    int target_window_height = document_info.height + chrome_height;
 
     // For some reason, this technique does not allow the user to resize
     // the browser window to greater than SIZE_LIMIT x SIZE_LIMIT. This is pretty
     // big, so we'll cap the allowable screenshot size to that.
     //
     // GDI+ limit after which it may report Generic error for some image types
     int SIZE_LIMIT = 65534; 
-    if (max_image_dimensions.bottom > SIZE_LIMIT) {
+    if (target_window_height > SIZE_LIMIT) {
       LOG(WARN) << "Required height is greater than limit. Truncating screenshot height.";
-      max_image_dimensions.bottom = SIZE_LIMIT;
-      document_info.height = max_image_dimensions.bottom - chrome_height;
+      target_window_height = SIZE_LIMIT;
+      document_info.height = target_window_height - chrome_height;
     }
-    if (max_image_dimensions.right > SIZE_LIMIT) {
+    if (target_window_width > SIZE_LIMIT) {
       LOG(WARN) << "Required width is greater than limit. Truncating screenshot width.";
-      max_image_dimensions.right = SIZE_LIMIT;
-      document_info.width = max_image_dimensions.right - chrome_width;
+      target_window_width = SIZE_LIMIT;
+      document_info.width = target_window_width - chrome_width;
     }
 
     long original_width = browser->GetWidth();
     long original_height = browser->GetHeight();
     LOG(DEBUG) << "Initial browser window sizes are (w, h): "
                << original_width << ", " << original_height;
 
-    bool requires_rezise = original_width <= max_image_dimensions.right ||
-                           original_height <= max_image_dimensions.bottom;
-
-    // The resize message is being ignored if the window appears to be
-    // maximized.  There's likely a way to bypass that. The kludgy way 
-    // is to unmaximize the window, then move on with setting the window
-    // to the dimensions we really want.  This is okay because we revert
-    // back to the original dimensions afterward.
     BOOL is_maximized = ::IsZoomed(ie_window_handle);
-    if (is_maximized) {
-      LOG(DEBUG) << "Window is maximized currently. Demaximizing.";
-      ::ShowWindow(ie_window_handle, SW_SHOWNORMAL);
-    }
+    bool requires_resize = original_width < target_window_width ||
+                           original_height < target_window_height;
+
+    if (requires_resize) {
+      // The resize message is being ignored if the window appears to be
+      // maximized.  There's likely a way to bypass that. The kludgy way 
+      // is to unmaximize the window, then move on with setting the window
+      // to the dimensions we really want.  This is okay because we revert
+      // back to the original dimensions afterward.
+      if (is_maximized) {
+        LOG(DEBUG) << "Window is maximized currently. Demaximizing.";
+        ::ShowWindow(ie_window_handle, SW_SHOWNORMAL);
+      }
 
-    HookSettings hook_settings;
-    hook_settings.window_handle = ie_window_handle;
-    hook_settings.hook_procedure_name = "ScreenshotWndProc";
-    hook_settings.hook_procedure_type = WH_CALLWNDPROC;
-    hook_settings.communication_type = OneWay;
-
-    HookProcessor hook;
-    if (!hook.CanSetWindowsHook(ie_window_handle)) {
-      LOG(WARN) << "Screenshot will be truncated! There is a mismatch "
-                << "in the bitness between the driver and browser. In "
-                << "particular, you are likely using a 32-bit "
-                << "IEDriverServer.exe and a 64-bit version of IE.";
+      RECT ie_window_rect;
+      ::GetWindowRect(ie_window_handle, &ie_window_rect);
+      ::SetWindowPos(ie_window_handle,
+                     NULL, 
+                     ie_window_rect.left,
+                     ie_window_rect.top,
+                     target_window_width,
+                     target_window_height,
+                     SWP_NOSENDCHANGING);
     }
-    hook.Initialize(hook_settings);
-
-    hook.PushData(sizeof(max_image_dimensions), &max_image_dimensions);
-    browser->SetWidth(max_image_dimensions.right);
-    
-    // Must re-push data because the resize causes a message to the
-    // IE window, and reading the data clears the buffer.
-    hook.PushData(sizeof(max_image_dimensions), &max_image_dimensions);
-    browser->SetHeight(max_image_dimensions.bottom);
-
-    hook.Dispose();
 
     // Capture the window's canvas to a DIB.
     BOOL created = this->image_->Create(document_info.width,
@@ -216,12 +195,14 @@ class ScreenshotCommandHandler : public IECommandHandler {
       LOG(WARN) << "PrintWindow API is not able to get content window screenshot";
     }
 
-    // Restore the browser to the original dimensions.
-    if (is_maximized) {
-      ::ShowWindow(ie_window_handle, SW_MAXIMIZE);
-    } else {
-      browser->SetHeight(original_height);
-      browser->SetWidth(original_width);
+    if (requires_resize) {
+      // Restore the browser to the original dimensions.
+      if (is_maximized) {
+        ::ShowWindow(ie_window_handle, SW_MAXIMIZE);
+      } else {
+        browser->SetHeight(original_height);
+        browser->SetWidth(original_width);
+      }
     }
 
     this->image_->ReleaseDC();
@@ -352,84 +333,5 @@ class ScreenshotCommandHandler : public IECommandHandler {
 
 } // namespace webdriver
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// This function is our message processor that we inject into the IEFrame 
-// process.  Its sole purpose is to process WM_GETMINMAXINFO messages and 
-// modify the max tracking size so that we can resize the IEFrame window to 
-// greater than the virtual screen resolution.  All other messages are 
-// delegated to the original IEFrame message processor.  This function 
-// uninjects itself immediately upon execution.
-LRESULT CALLBACK MinMaxInfoHandler(HWND hwnd,
-                                   UINT message,
-                                   WPARAM wParam,
-                                   LPARAM lParam) {
-  // Grab a reference to the original message processor.
-  HANDLE original_message_proc = ::GetProp(hwnd,
-                                           L"__original_message_processor__");
-  ::RemoveProp(hwnd, L"__original_message_processor__");
-
-  // Uninject this method.
-  ::SetWindowLongPtr(hwnd,
-                     GWLP_WNDPROC,
-                     reinterpret_cast<LONG_PTR>(original_message_proc));
-
-  if (WM_GETMINMAXINFO == message) {
-    MINMAXINFO* minMaxInfo = reinterpret_cast<MINMAXINFO*>(lParam);
-    RECT max_size;
-    webdriver::HookProcessor::CopyDataFromBuffer(sizeof(RECT), reinterpret_cast<void*>(&max_size));
-    minMaxInfo->ptMaxTrackSize.x = max_size.right;
-    minMaxInfo->ptMaxTrackSize.y = max_size.bottom;
-
-    // We're not going to pass this message onto the original message
-    // processor, so we should return 0, per the documentation for
-    // the WM_GETMINMAXINFO message.
-    return 0;
-  }
-
-  // All other messages should be handled by the original message processor.
-  return ::CallWindowProc(reinterpret_cast<WNDPROC>(original_message_proc),
-                          hwnd,
-                          message,
-                          wParam,
-                          lParam);
-}
-
-// Many thanks to sunnyandy for helping out with this approach.  What we're 
-// doing here is setting up a Windows hook to see incoming messages to the
-// IEFrame's message processor.  Once we find one that's WM_GETMINMAXINFO,
-// we inject our own message processor into the IEFrame process to handle 
-// that one message. WM_GETMINMAXINFO is sent on a resize event so the process
-// can see how large a window can be. By modifying the max values, we can allow
-// a window to be sized greater than the (virtual) screen resolution would
-// otherwise allow.
-//
-// See the discussion here: http://www.codeguru.com/forum/showthread.php?p=1889928
-LRESULT CALLBACK ScreenshotWndProc(int nCode, WPARAM wParam, LPARAM lParam) {
-  CWPSTRUCT* call_window_proc_struct = reinterpret_cast<CWPSTRUCT*>(lParam);
-  if (WM_COPYDATA == call_window_proc_struct->message) {
-    COPYDATASTRUCT* data = reinterpret_cast<COPYDATASTRUCT*>(call_window_proc_struct->lParam);
-    webdriver::HookProcessor::CopyDataToBuffer(data->cbData, data->lpData);
-  } else if (WM_GETMINMAXINFO == call_window_proc_struct->message) {
-    // Inject our own message processor into the process so we can modify
-    // the WM_GETMINMAXINFO message. It is not possible to modify the 
-    // message from this hook, so the best we can do is inject a function
-    // that can.
-    LONG_PTR proc = ::SetWindowLongPtr(call_window_proc_struct->hwnd,
-                                       GWLP_WNDPROC,
-                                       reinterpret_cast<LONG_PTR>(MinMaxInfoHandler));
-    ::SetProp(call_window_proc_struct->hwnd,
-              L"__original_message_processor__",
-              reinterpret_cast<HANDLE>(proc));
-  }
-
-  return ::CallNextHookEx(NULL, nCode, wParam, lParam);
-}
-
-#ifdef __cplusplus
-}
-#endif
 
 #endif // WEBDRIVER_IE_SCREENSHOTCOMMANDHANDLER_H_