Implement HiDPI support in Pepper dev interface

ppapi/cpp/dev/graphics_2d_dev.h

+// 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.
+
+#ifndef PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_
+#define PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_
+
+#include "ppapi/cpp/graphics_2d.h"
+
+namespace pp {
+
+// Graphics2DDev is a version of Graphics2D that exposes under-development  APIs
+// for HiDPI
+class Graphics2DDev : public Graphics2D {
+ public:
+  /// Default constructor for creating an is_null()
+  /// <code>Graphics2DDev</code> object.
+  Graphics2DDev() : Graphics2D() {}
+
+  // Constructor for creating a <code>Graphics2DDev</code> object from an
+  // existing <code>Graphics2D</code> object.
+  Graphics2DDev(const Graphics2D& other) : Graphics2D(other) {}
+
+  virtual ~Graphics2DDev() {}
+
+  /// SetScale() sets the scale factor that will be applied when painting the
+  /// graphics context onto the output device. Typically, if rendering at device
+  /// resolution is desired, the context would be created with the width and
+  /// height scaled up by the view's GetDeviceScale and SetScale called with a
+  /// scale of 1.0 / GetDeviceScale(). For example, if the view resource passed
+  /// to DidChangeView has a rectangle of (w=200, h=100) and a device scale of
+  /// 2.0, one would call Create with a size of (w=400, h=200) and then call
+  /// SetScale with 0.5. One would then treat each pixel in the context as a
+  /// single device pixel.
+  ///
+  /// @param[in] scale The scale to apply when painting.
+  ///
+  /// @return Returns <code>true</code> on success or <code>false</code>
+  /// if the resource is invalid or the scale factor is 0 or less.
+  bool SetScale(float scale);
+
+  /// GetScale() gets the scale factor that will be applied when painting the
+  /// graphics context onto the output device.
+  ///
+  /// @return Returns the scale factor for the graphics context. If the resource
+  /// is invalid, 0.0 will be returned.
+  float GetScale();
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_GRAPHICS_2D_DEV_H_