android: Fix inconsistent sizes in GetScaledContentBitmap

content/browser/renderer_host/render_widget_host_view_android.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 "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/android/sys_utils.h"
 #include "base/basictypes.h"
@@ skipping 48 matching lines @@
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/base/android/window_android.h"
 #include "ui/base/android/window_android_compositor.h"
 #include "ui/events/gesture_detection/gesture_config_helper.h"
 #include "ui/events/gesture_detection/motion_event.h"
 #include "ui/gfx/android/device_display_info.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/point_conversions.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size_conversions.h"
 
 namespace content {
 
 namespace {
 
 const int kUndefinedOutputSurfaceId = -1;
 
 // Used to accomodate finite precision when comparing scaled viewport and
@@ skipping 213 matching lines @@
 void RenderWidgetHostViewAndroid::GetScaledContentBitmap(
     float scale,
     SkBitmap::Config bitmap_config,
     gfx::Rect src_subrect,
     const base::Callback<void(bool, const SkBitmap&)>& result_callback) {
   if (!IsSurfaceAvailableForCopy()) {
     result_callback.Run(false, SkBitmap());
     return;
   }
 
-  gfx::Size bounds = layer_->bounds();
-  if (src_subrect.IsEmpty())
-    src_subrect = gfx::Rect(bounds);
-  DCHECK_LE(src_subrect.width() + src_subrect.x(), bounds.width());
-  DCHECK_LE(src_subrect.height() + src_subrect.y(), bounds.height());
   const gfx::Display& display =
       gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
   float device_scale_factor = display.device_scale_factor();
   DCHECK_GT(device_scale_factor, 0);
-  gfx::Size dst_size(
-      gfx::ToCeiledSize(gfx::ScaleSize(bounds, scale / device_scale_factor)));
+
+  gfx::Size bounds = layer_->bounds();
+
+  gfx::Size dst_size_in_dip(gfx::ToCeiledSize(gfx::ScaleSize(bounds, scale)));
+
+  gfx::RectF src_subrect_in_dip_f(gfx::ScaleRect(
+      ConvertRectToDIP(device_scale_factor, src_subrect), scale));

[no sievers, 2014/06/11 21:39:11]

Why does the src_subrect get scaled by |scale|?

[powei, 2014/06/11 21:46:12]

I think |src_subrect| assumes its space to be pre-scaled.  It's only used for
the NTP thumbnails.

+
+  gfx::Rect src_subrect_in_dip(
+      gfx::ToFlooredPoint(src_subrect_in_dip_f.origin()),
+      gfx::ToCeiledSize(src_subrect_in_dip_f.size()));
+
+  if (src_subrect_in_dip.IsEmpty())
+    src_subrect_in_dip = gfx::Rect(dst_size_in_dip);

[no sievers, 2014/06/11 21:39:11]

When does this happen?

[powei, 2014/06/11 21:46:11]

It's a somewhat hacky convention that when |src_subrect| is empty, then just
take the entire content.  Added here
(https://codereview.chromium.org/173023005/)  when we were fixing NTP thumbnails
and yet wanted to keep this method for tab switcher thumbnails.  So tab-switcher
thumbnails also pass in empty |src_subrect|s.

+
+  DCHECK_LE(src_subrect_in_dip.width() + src_subrect_in_dip.x(),
+            bounds.width());
+  DCHECK_LE(src_subrect_in_dip.height() + src_subrect_in_dip.y(),
+            bounds.height());
+
   CopyFromCompositingSurface(
-      src_subrect, dst_size, result_callback, bitmap_config);
+      src_subrect_in_dip, dst_size_in_dip, result_callback, bitmap_config);
 }
 
 bool RenderWidgetHostViewAndroid::HasValidFrame() const {
   if (!content_view_core_)
     return false;
   if (!layer_)
     return false;
 
   if (texture_size_in_layer_.IsEmpty())
     return false;
@@ skipping 1124 matching lines @@
   results->availableRect = display.work_area();
   results->deviceScaleFactor = display.device_scale_factor();
   results->orientationAngle = display.RotationAsDegree();
   gfx::DeviceDisplayInfo info;
   results->depth = info.GetBitsPerPixel();
   results->depthPerComponent = info.GetBitsPerComponent();
   results->isMonochrome = (results->depthPerComponent == 0);
 }
 
 } // namespace content