Fix Aura backing store to work with non-integer scale factors.

content/browser/renderer_host/backing_store_aura.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/backing_store_aura.h"
 
 #include "content/browser/renderer_host/dip_util.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/public/browser/render_widget_host.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/vector2d_conversions.h"
 
+namespace {
+
+gfx::Size ToPixelSize(gfx::Size dipSize, float scale) {
+  return gfx::ToCeiledSize(gfx::ScaleSize(dipSize, scale));
+}
+
+}  // namespace
+
+
 namespace content {
 
 // Assume that somewhere along the line, someone will do width * height * 4
 // with signed numbers. If the maximum value is 2**31, then 2**31 / 4 =
 // 2**29 and floor(sqrt(2**29)) = 23170.
 
 // Max height and width for layers
 static const int kMaxVideoLayerSize = 23170;
 
 BackingStoreAura::BackingStoreAura(RenderWidgetHost* widget,
                                    const gfx::Size& size)
     : BackingStore(widget, size) {
   device_scale_factor_ =
       ui::GetScaleFactorScale(GetScaleFactorForView(widget->GetView()));
-  gfx::Size pixel_size = gfx::ToFlooredSize(
-      gfx::ScaleSize(size, device_scale_factor_));
+  gfx::Size pixel_size = ToPixelSize(size, device_scale_factor_);
   bitmap_.setConfig(SkBitmap::kARGB_8888_Config,
       pixel_size.width(), pixel_size.height());
   bitmap_.allocPixels();
   canvas_.reset(new SkCanvas(bitmap_));
 }
 
 BackingStoreAura::~BackingStoreAura() {
 }
 
 void BackingStoreAura::SkiaShowRect(const gfx::Point& point,
                                     gfx::Canvas* canvas) {
   gfx::ImageSkia image = gfx::ImageSkia(gfx::ImageSkiaRep(bitmap_,
       ui::GetScaleFactorFromScale(device_scale_factor_)));
   canvas->DrawImageInt(image, point.x(), point.y());
 }
 
 void BackingStoreAura::ScaleFactorChanged(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;
 
-  gfx::Size old_pixel_size = gfx::ToFlooredSize(
-      gfx::ScaleSize(size(), device_scale_factor_));
+  gfx::Size old_pixel_size = ToPixelSize(size(), device_scale_factor_);
   device_scale_factor_ = device_scale_factor;
 
-  gfx::Size pixel_size = gfx::ToFlooredSize(
-      gfx::ScaleSize(size(), device_scale_factor_));
+  gfx::Size pixel_size = ToPixelSize(size(), device_scale_factor_);
   SkBitmap new_bitmap;
   new_bitmap.setConfig(SkBitmap::kARGB_8888_Config,
       pixel_size.width(), pixel_size.height());
   new_bitmap.allocPixels();
   scoped_ptr<SkCanvas> new_canvas(new SkCanvas(new_bitmap));
 
   // Copy old contents; a low-res flash is better than a black flash.
   SkPaint copy_paint;
   copy_paint.setXfermodeMode(SkXfermode::kSrc_Mode);
   SkIRect src_rect = SkIRect::MakeWH(old_pixel_size.width(),
                                      old_pixel_size.height());
   SkRect dst_rect = SkRect::MakeWH(pixel_size.width(), pixel_size.height());
   new_canvas.get()->drawBitmapRect(bitmap_, &src_rect, dst_rect, &copy_paint);
 
   canvas_.swap(new_canvas);
   bitmap_ = new_bitmap;
 }
 
 size_t BackingStoreAura::MemorySize() {
   // NOTE: The computation may be different when the canvas is a subrectangle of
   // a larger bitmap.
-  return gfx::ToFlooredSize(
-      gfx::ScaleSize(size(), device_scale_factor_)).GetArea() * 4;
+  return ToPixelSize(size(), device_scale_factor_).GetArea() * 4;
 }
 
 void BackingStoreAura::PaintToBackingStore(
     RenderProcessHost* process,
     TransportDIB::Id bitmap,
     const gfx::Rect& bitmap_rect,
     const std::vector<gfx::Rect>& copy_rects,
     float scale_factor,
     const base::Closure& completion_callback,
     bool* scheduled_completion_callback) {
   *scheduled_completion_callback = false;
   if (bitmap_rect.IsEmpty())
     return;
 
-  gfx::Rect pixel_bitmap_rect = gfx::ToEnclosedRect(
+  gfx::Rect pixel_bitmap_rect = gfx::ToEnclosingRect(
       gfx::ScaleRect(bitmap_rect, scale_factor));
 
   const int width = pixel_bitmap_rect.width();
   const int height = pixel_bitmap_rect.height();
 
   if (width <= 0 || width > kMaxVideoLayerSize ||
       height <= 0 || height > kMaxVideoLayerSize)
     return;
 
   TransportDIB* dib = process->GetTransportDIB(bitmap);
@@ skipping 53 matching lines @@
 
   SkIRect skrect = SkIRect::MakeXYWH(rect.x(), rect.y(), width, height);
   SkBitmap b;
   if (!canvas_->readPixels(skrect, &b))
     return false;
   SkCanvas(output->GetBitmap()).writePixels(b, rect.x(), rect.y());
   return true;
 }
 
 }  // namespace content