Introduce XGetImage() for GrabWindowSnapshot() in ChromeOS.

ui/aura/root_window_host_linux.cc

 // Copyright (c) 2012 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 "ui/aura/root_window_host_linux.h"
 
 #include <X11/Xatom.h>
 #include <X11/Xcursor/Xcursor.h>
+#include <X11/Xlib.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/Xfixes.h>
 #include <X11/extensions/Xrandr.h>
 #include <algorithm>
 
 #include "base/message_pump_x.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
 #include "grit/ui_resources_standard.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/aura/client/user_gesture_client.h"
 #include "ui/aura/dispatcher_linux.h"
 #include "ui/aura/env.h"
 #include "ui/aura/event.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/cursor/cursor.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/touch/touch_factory.h"
 #include "ui/base/view_prop.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/compositor/layer.h"
+#include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/image/image.h"
 
 using std::max;
 using std::min;
 
 namespace aura {
 
 namespace {
 
 // Standard Linux mouse buttons for going back and forward.
@@ skipping 755 matching lines @@
   static const char* k_NET_WM_USER_TIME = "_NET_WM_USER_TIME";
   focus_when_shown_ = focus_when_shown;
   if (IsWindowManagerPresent() && !focus_when_shown_) {
     ui::SetIntProperty(xwindow_,
                        k_NET_WM_USER_TIME,
                        k_NET_WM_USER_TIME,
                        0);
   }
 }
 
+bool RootWindowHostLinux::GrabWindowSnapshot(
+    std::vector<unsigned char>* png_representation,
+    const gfx::Rect& snapshot_bounds) {
+  XImage* image = XGetImage(
+      xdisplay_, xwindow_,
+      snapshot_bounds.x(), snapshot_bounds.y(),
+      snapshot_bounds.width(), snapshot_bounds.height(),
+      AllPlanes, ZPixmap);
+
+  unsigned char* data = reinterpret_cast<unsigned char*>(image->data);
+  gfx::PNGCodec::Encode(data, gfx::PNGCodec::FORMAT_BGRA,

[Daniel Erat, 2012/05/14 23:17:40]

I don't love the inflexibility of doing PNG encoding here (and on the UI thread)
instead of handing back raw data.  Are you mostly doing this so you can call
XFree() here without needing to copy the data?

[Jun Mukai, 2012/05/15 22:39:24]

That's why original browser::GrabWindowSnapshot returns PNG format.  Also, the
response format would get unclear if win/mac impls of root_window_host want to
support this method.

+                        snapshot_bounds.size(),
+                        image->width * image->bits_per_pixel / 8,
+                        true, std::vector<gfx::PNGCodec::Comment>(),
+                        png_representation);
+  XFree(image);
+  return true;
+}
+
 void RootWindowHostLinux::PostNativeEvent(
     const base::NativeEvent& native_event) {
   DCHECK(xwindow_);
   DCHECK(xdisplay_);
   XEvent xevent = *native_event;
   xevent.xany.display = xdisplay_;
   xevent.xany.window = xwindow_;
 
   switch (xevent.type) {
     case EnterNotify:
@@ skipping 50 matching lines @@
       ui::ViewProp::GetValue(accelerated_widget, kRootWindowHostLinuxKey));
 }
 
 // static
 gfx::Size RootWindowHost::GetNativeScreenSize() {
   ::Display* xdisplay = base::MessagePumpX::GetDefaultXDisplay();
   return gfx::Size(DisplayWidth(xdisplay, 0), DisplayHeight(xdisplay, 0));
 }
 
 }  // namespace aura