ui/views/drag_utils.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/views/drag_utils.h"

#include "ui/gfx/canvas.h"
#include "ui/gfx/display.h"
#include "ui/gfx/screen.h"
#include "ui/gfx/size.h"
#include "ui/views/widget/widget.h"

namespace {

float GetDeviceScaleForNativeView(views::Widget* widget) {
  float device_scale = 1.0f;
  // The following code should work on other platforms as well. But we do not
  // yet care about device scale factor on other platforms. So to keep drag and
  // drop behavior on other platforms un-touched, we wrap this in the #if guard.
  if (widget && widget->GetNativeView()) {
    gfx::NativeView view = widget->GetNativeView();
    gfx::Display display = gfx::Screen::GetScreenFor(view)->
        GetDisplayNearestWindow(view);
    device_scale = display.device_scale_factor();
  }
  return device_scale;
}

}  // namespace

namespace views {

gfx::Canvas* GetCanvasForDragImage(views::Widget* widget,
                                   const gfx::Size& canvas_size) {
  float device_scale = GetDeviceScaleForNativeView(widget);
  return new gfx::Canvas(canvas_size, device_scale, false);
}

}  // namespace views