Send array of paint rects and bitmaps as opposed to a Union

chrome/browser/renderer_host/backing_store.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef CHROME_BROWSER_RENDERER_HOST_BACKING_STORE_H_
 #define CHROME_BROWSER_RENDERER_HOST_BACKING_STORE_H_
 
 #include "base/basictypes.h"
 #include "base/gfx/rect.h"
 #include "base/gfx/size.h"
@@ skipping 45 matching lines @@
   skia::PlatformCanvas* canvas() { return &canvas_; }
 #elif defined(OS_LINUX)
   // Copy from the server-side backing store to the target window
   //   display: the display of the backing store and target window
   //   damage: the area to copy
   //   target: the X id of the target window
   void ShowRect(const gfx::Rect& damage, XID target);
 #endif
 
   // Paints the bitmap from the renderer onto the backing store.
+  // bitmap_rect is the rect of the whole bitmap, and paint_rect
+  // is a sub-rect of bitmap that we want to draw.
   void PaintRect(base::ProcessHandle process,
                  TransportDIB* bitmap,
-                 const gfx::Rect& bitmap_rect);
+                 const gfx::Rect& bitmap_rect,
+                 const gfx::Rect& paint_rect);
 
   // Scrolls the given rect in the backing store, replacing the given region
   // identified by |bitmap_rect| by the bitmap in the file identified by the
   // given file handle.
   void ScrollRect(base::ProcessHandle process,
                   TransportDIB* bitmap, const gfx::Rect& bitmap_rect,
                   int dx, int dy,
                   const gfx::Rect& clip_rect,
                   const gfx::Size& view_size);
 
  private:
   // The size of the backing store.
   gfx::Size size_;
 
 #if defined(OS_WIN)
 
   // The backing store dc.
   HDC hdc_;
   // Handle to the backing store dib.
   HANDLE backing_store_dib_;
   // Handle to the original bitmap in the dc.
   HANDLE original_bitmap_;
   // Number of bits per pixel of the screen.
   int color_depth_;
 #elif defined(OS_MACOSX)
   skia::PlatformCanvas canvas_;
 #elif defined(OS_LINUX)
   // Paints the bitmap from the renderer onto the backing store without
   // using Xrender to composite the pixmaps.
+  // bitmap_rect is the rect of the whole bitmap, and paint_rect
+  // is a sub-rect of bitmap that we want to draw.
   void PaintRectWithoutXrender(TransportDIB* bitmap,
-                               const gfx::Rect& bitmap_rect);
+                               const gfx::Rect& bitmap_rect,
+                               const gfx::Rect& paint_rect);
 
   // This is the connection to the X server where this backing store will be
   // displayed.
   Display *const display_;
   // If this is true, then |connection_| is good for MIT-SHM (X shared memory).
   const bool use_shared_memory_;
   // If this is true, then we can use Xrender to composite our pixmaps.
   const bool use_render_;
   // If |use_render_| is false, this is the number of bits-per-pixel for |depth|
   int pixmap_bpp_;
   // This is the depth of the target window.
   const int visual_depth_;
   // The parent window (probably a GtkDrawingArea) for this backing store.
   const XID root_window_;
   // This is a handle to the server side pixmap which is our backing store.
   XID pixmap_;
   // This is the RENDER picture pointing at |pixmap_|.
   XID picture_;
   // This is a default graphic context, used in XCopyArea
   void* pixmap_gc_;
 #endif
 
+  // Sanity checks on the size of the rects to draw so that we don't allocate
+  // enourmous pixmaps.
+  static int kMaxBitmapLengthAllowed;
+
   DISALLOW_COPY_AND_ASSIGN(BackingStore);
 };
 
 // BackingStoreManager ---------------------------------------------------------
 
 // This class manages backing stores in the browsr. Every RenderWidgetHost is
 // associated with a backing store which it requests from this class.  The
 // hosts don't maintain any references to the backing stores.  These backing
 // stores are maintained in a cache which can be trimmed as needed.
 class BackingStoreManager {
@@ skipping 19 matching lines @@
   // bitmap_rect
   //   The rect to be painted into the backing store
   // needs_full_paint
   //   Set if we need to send out a request to paint the view
   //   to the renderer.
   static BackingStore* PrepareBackingStore(RenderWidgetHost* host,
                                            const gfx::Size& backing_store_size,
                                            base::ProcessHandle process_handle,
                                            TransportDIB* bitmap,
                                            const gfx::Rect& bitmap_rect,
+                                           const gfx::Rect& paint_rect,
                                            bool* needs_full_paint);
 
   // Returns a matching backing store for the host.
   // Returns NULL if we fail to find one.
   static BackingStore* Lookup(RenderWidgetHost* host);
 
   // Removes the backing store for the host.
   static void RemoveBackingStore(RenderWidgetHost* host);
 
  private:
   // Not intended for instantiation.
   BackingStoreManager() {}
 
   DISALLOW_COPY_AND_ASSIGN(BackingStoreManager);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_BACKING_STORE_H_