Change snasphotting API to take in a bounds Rect

chrome/browser/ui/window_snapshot/window_snapshot_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/window_snapshot/window_snapshot.h"
 
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/scoped_hdc.h"
 #include "base/win/scoped_select_object.h"
 #include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/gdi_util.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 namespace browser {
 
 gfx::Rect GrabWindowSnapshot(gfx::NativeWindow window_handle,
-                             std::vector<unsigned char>* png_representation) {
+                             std::vector<unsigned char>* png_representation,
+                             gfx::Rect snapshot_bounds) {
   // Create a memory DC that's compatible with the window.
   HDC window_hdc = GetWindowDC(window_handle);
   base::win::ScopedCreateDC mem_hdc(CreateCompatibleDC(window_hdc));
 
   // Create a DIB that's the same size as the window.
   RECT content_rect = {0, 0, 0, 0};
   ::GetWindowRect(window_handle, &content_rect);
   content_rect.right++;  // Match what PrintWindow wants.
-  int width = content_rect.right - content_rect.left;
-  int height = content_rect.bottom - content_rect.top;
+
+  if (snapshot_bounds.IsEmpty()) {
+    snapshot_bounds(gfx::Size(content_rect.right - content_rect.left,
+                              content_rect.bottom - content_rect.top));
+  } else {
+    snapshot_bounds.Offset(content_rect.left, content_rect.top);
+    DCHECK(snapshot_bounds.right() <= content_rect.right);
+    DCHECK(snapshot_bounds.bottom() <= content_rect.bottom); 
+  }
+ 
   BITMAPINFOHEADER hdr;
-  gfx::CreateBitmapHeader(width, height, &hdr);
+  gfx::CreateBitmapHeader(snapshot_bounds.width(),
+                          snapshot_bounds.height(),
+                          &hdr);
   unsigned char *bit_ptr = NULL;
   base::win::ScopedBitmap bitmap(
       CreateDIBSection(mem_hdc,
                        reinterpret_cast<BITMAPINFO*>(&hdr),
                        DIB_RGB_COLORS,
                        reinterpret_cast<void **>(&bit_ptr),
                        NULL, 0));
 
   base::win::ScopedSelectObject select_bitmap(mem_hdc, bitmap);
   // Clear the bitmap to white (so that rounded corners on windows
   // show up on a white background, and strangely-shaped windows
   // look reasonable). Not capturing an alpha mask saves a
   // bit of space.
-  PatBlt(mem_hdc, 0, 0, width, height, WHITENESS);
+  PatBlt(mem_hdc, 0, 0, snapshot_bounds.width(), snapshot_bounds.height(),
+         WHITENESS);
   // Grab a copy of the window
   // First, see if PrintWindow is defined (it's not in Windows 2000).
   typedef BOOL (WINAPI *PrintWindowPointer)(HWND, HDC, UINT);
   PrintWindowPointer print_window =
       reinterpret_cast<PrintWindowPointer>(
           GetProcAddress(GetModuleHandle(L"User32.dll"), "PrintWindow"));
 
   // If PrintWindow is defined, use it.  It will work on partially
   // obscured windows, and works better for out of process sub-windows.
   // Otherwise grab the bits we can get with BitBlt; it's better
   // than nothing and will work fine in the average case (window is
   // completely on screen).
-  if (print_window)
+  if (snapshot_bounds.origin() != gfx::Point() && print_window)
     (*print_window)(window_handle, mem_hdc, 0);
   else
-    BitBlt(mem_hdc, 0, 0, width, height, window_hdc, 0, 0, SRCCOPY);
+    BitBlt(mem_hdc, 0, 0, snapshot_bounds.width(), snapshot_bounds.height(),
+           window_hdc, snapshot_bounds.x(), snapshot_bounds.y(), SRCCOPY);
 
   // We now have a copy of the window contents in a DIB, so
   // encode it into a useful format for posting to the bug report
   // server.
   gfx::PNGCodec::Encode(bit_ptr, gfx::PNGCodec::FORMAT_BGRA,
-                        gfx::Size(width, height), width * 4, true,
+                        snapshot_bounds.size(), width * 4, true,
                         std::vector<gfx::PNGCodec::Comment>(),
                         png_representation);
 
   ReleaseDC(window_handle, window_hdc);
 
-  return gfx::Rect(width, height);
+  return gfx::Rect(snapshot_bounds.size());
 }
 
 }  // namespace browser