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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "ui/views/drag_utils.h"
      6 
      7 #include "ui/gfx/canvas.h"
      8 #include "ui/gfx/display.h"
      9 #include "ui/gfx/screen.h"
     10 #include "ui/gfx/size.h"
     11 #include "ui/views/widget/widget.h"
     12 
     13 namespace {
     14 
     15 float GetDeviceScaleForNativeView(views::Widget* widget) {
     16   float device_scale = 1.0f;
     17   // The following code should work on other platforms as well. But we do not
     18   // yet care about device scale factor on other platforms. So to keep drag and
     19   // drop behavior on other platforms un-touched, we wrap this in the #if guard.
     20   if (widget && widget->GetNativeView()) {
     21     gfx::NativeView view = widget->GetNativeView();
     22     gfx::Display display = gfx::Screen::GetScreenFor(view)->
     23         GetDisplayNearestWindow(view);
     24     device_scale = display.device_scale_factor();
     25   }
     26   return device_scale;
     27 }
     28 
     29 }  // namespace
     30 
     31 namespace views {
     32 
     33 gfx::Canvas* GetCanvasForDragImage(views::Widget* widget,
     34                                    const gfx::Size& canvas_size) {
     35   float device_scale = GetDeviceScaleForNativeView(widget);
     36   return new gfx::Canvas(canvas_size, device_scale, false);
     37 }
     38 
     39 }  // namespace views
     40