Change snasphotting API to take in a bounds Rect

chrome/browser/ui/window_snapshot/window_snapshot_gtk.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 <gdk/gdkx.h>
 #include <gtk/gtk.h>
 
 #include "base/logging.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/rect.h"
 
 namespace browser {
 
+namespace {
+gfx::Rect GetWindowBounds(gfx::NativeWindow window_handle) {

[jonathan.backer, 2011/11/14 13:45:02]

There are two functions in ui/base/x11_util.h that you could use in place of
this function:

GetX11WindowFromGtkWidget and
GetWindowRect

[sky, 2011/11/14 16:23:09]

nit: newline between 16 and 17.

+  GdkWindow* gdk_window = GTK_WIDGET(window_handle)->window;
+  Display* display = GDK_WINDOW_XDISPLAY(gdk_window);
+  XID win = GDK_WINDOW_XID(gdk_window);
+  XWindowAttributes attr;
+  if (XGetWindowAttributes(display, win, &attr) == 0) {
+    return gfx::Rect();
+  }
+  return gfx::Rect(0, 0, attr.width, attr.height);
+}
+
+} // namespace
+
 static cairo_status_t SnapshotCallback(
     void *closure, const unsigned char *data, unsigned int length) {
   std::vector<unsigned char>* png_representation =
       static_cast<std::vector<unsigned char>*>(closure);
 
   size_t old_size = png_representation->size();
   png_representation->resize(old_size + length);
   memcpy(&(*png_representation)[old_size], data, length);
   return CAIRO_STATUS_SUCCESS;
 }
 
-gfx::Rect GrabWindowSnapshot(gfx::NativeWindow gtk_window,
+gfx::Rect GrabWindowSnapshot(gfx::NativeWindow window_handle,
                              std::vector<unsigned char>* png_representation) {
-  GdkWindow* gdk_window = GTK_WIDGET(gtk_window)->window;
-  Display* display = GDK_WINDOW_XDISPLAY(gdk_window);
-  XID win = GDK_WINDOW_XID(gdk_window);
-  XWindowAttributes attr;
-  if (XGetWindowAttributes(display, win, &attr) == 0) {
+  return GrabWindowSnapshot(window_handle, png_representation,
+    GetWindowBounds(window_handle));
+}
+
+gfx::Rect GrabWindowSnapshot(gfx::NativeWindow window_handle,
+                             std::vector<unsigned char>* png_representation,
+                             const gfx::Rect snapshot_bounds) {
+  gfx::Rect window_bounds = GetWindowBounds(window_handle);
+  if (window_bounds.IsEmpty()) {
     LOG(ERROR) << "Couldn't get window attributes";
     return gfx::Rect();
   }
+
+  DCHECK(snapshot_bounds.right() <= window_bounds.width());
+  DCHECK(snapshot_bounds.bottom() <= window_bounds.height());
+
+  GdkWindow* gdk_window = GTK_WIDGET(window_handle)->window;

[jonathan.backer, 2011/11/14 13:45:02]

GetX11WindowFromGtkWidget

+  Display* display = GDK_WINDOW_XDISPLAY(gdk_window);

[jonathan.backer, 2011/11/14 13:45:02]

GetXDisplay?

[pkotwicz, 2011/11/15 15:56:12]

It seems as if we are trying to deprecate this method. But its a good method.

[Elliot Glaysher, 2011/11/15 18:06:34]

Please don't use GetXDisplay(). We aren't guaranteed to have only a single
Display per process, especially with sshing around.

+  XID win = GDK_WINDOW_XID(gdk_window);
+
   XImage* image = XGetImage(
-      display, win, 0, 0, attr.width, attr.height, AllPlanes, ZPixmap);
+      display, win, snapshot_bounds.x(), snapshot_bounds.y(),
+      snapshot_bounds.width(), snapshot_bounds.height(), AllPlanes, ZPixmap);
   if (!image) {
     LOG(ERROR) << "Couldn't get image";
     return gfx::Rect();
   }
   if (image->depth != 24) {
     LOG(ERROR)<< "Unsupported image depth " << image->depth;
     return gfx::Rect();
   }
   cairo_surface_t* surface =
       cairo_image_surface_create_for_data(
           reinterpret_cast<unsigned char*>(image->data),
           CAIRO_FORMAT_RGB24,
           image->width,
           image->height,
           image->bytes_per_line);
 
   if (!surface) {
     LOG(ERROR) << "Unable to create Cairo surface from XImage data";
     return gfx::Rect();
   }
   cairo_surface_write_to_png_stream(
       surface, SnapshotCallback, png_representation);
   cairo_surface_destroy(surface);
 
   return gfx::Rect(image->width, image->height);
 }
 
 }  // namespace browser