Implement HiDPI support in Pepper dev interface

ppapi/cpp/private/graphics_2d_private.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_PRIVATE_GRAPHICS_2D_PRIVATE_H_
+#define PPAPI_CPP_PRIVATE_GRAPHICS_2D_PRIVATE_H_
+
+#include "ppapi/cpp/graphics_2d.h"
+
+namespace pp {
+
+// Graphics2DPrivate is a version of Graphics2D that exposes private APIs
+// for HiDPI
+class Graphics2DPrivate : public Graphics2D {
+ public:
+  /// Default constructor for creating an is_null()
+  /// <code>Graphics2DPrivate</code> object.
+  Graphics2DPrivate();
+
+  /// The copy constructor for Graphics2DPrivate. The underlying 2D context is
+  /// not copied; this constructor creates another reference to the original 2D
+  /// context.
+  ///
+  /// @param[in] other A pointer to a <code>Graphics2DPrivate</code> context.
+  Graphics2DPrivate(const Graphics2DPrivate& other);
+
+  /// A constructor allocating a new 2D graphics context with the given size
+  /// in the browser, resulting object will be is_null() if the allocation
+  /// failed.
+  ///
+  /// @param[in] instance The instance with which this resource will be
+  /// associated.
+  ///
+  /// @param[in] size The size of the 2D graphics context in the browser,
+  /// measured in density-independent pixels (DIPs). Note that using this
+  /// constructor will result in a 2D context with a scale between pixels in the
+  /// context and DIPs of 1.0.
+  ///
+  /// @param[in] is_always_opaque Set the <code>is_always_opaque</code> flag
+  /// to true if you know that you will be painting only opaque data to this
+  /// context. This option will disable blending when compositing the module
+  /// with the web page, which might give higher performance on some computers.
+  ///
+  /// If you set <code>is_always_opaque</code>, your alpha channel should
+  /// always be set to 0xFF or there may be painting artifacts. The alpha values
+  /// overwrite the destination alpha values without blending when
+  /// <code>is_always_opaque</code> is true.
+  Graphics2DPrivate(const InstanceHandle& instance,
+                    const Size& size,
+                    bool is_always_opaque);
+
+  /// A constructor allocating a new 2D graphics context with the given size and
+  /// scale factor in the browser, resulting object will be is_null() if the
+  /// allocation failed.
+  ///
+  /// @param[in] instance The instance with which this resource will be
+  /// associated.
+  ///
+  /// @param[in] size The size of the 2D graphics context in the browser,
+  /// measured in pixels. The browser will use the scale_factor to properly
+  /// map between 1 pixel in the context and 1 density-independent pixel on the
+  /// display.
+  ///
+  /// @param[in] is_always_opaque Set the <code>is_always_opaque</code> flag
+  /// to true if you know that you will be painting only opaque data to this
+  /// context. This option will disable blending when compositing the module
+  /// with the web page, which might give higher performance on some computers.
+  ///
+  /// If you set <code>is_always_opaque</code>, your alpha channel should
+  /// always be set to 0xFF or there may be painting artifacts. The alpha values
+  /// overwrite the destination alpha values without blending when
+  /// <code>is_always_opaque</code> is true.
+  ///
+  /// @param[in] scale The scaling factor between pixels in this context and
+  /// DIPs. For rendering at device resolution, this will typically be equal to
+  /// the device scale of the view resource passed to DidChangeView.
+  /// 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 this
+  /// constructor with a size of (w=400, h=200) and a scale of 2.0, then treat
+  /// each pixel in the context as a single device pixel.
+  Graphics2DPrivate(const InstanceHandle& instance,
+                    const Size& size,
+                    bool is_always_opaque,
+                    float scale);
+
+  /// A destructor that decrements the reference count of a
+  /// <code>Graphics2DPrivate</code> object made using the previous copy
+  /// constructor. It is possible that the destructor does not toally destroy
+  /// the underlying 2D context if there are outstanding references to it.
+  virtual ~Graphics2DPrivate();
+
+  /// This function assigns one 2D graphics cntext to this 2D graphics context.
+  /// This function increases the reference count of the 2D resource of the
+  /// other 2D graphics context while decrementing the reference counter
+  /// of this 2D graphics context.
+  ///
+  /// @param[in] other An other 2D graphics context.
+  ///
+  /// @return A new Graphics2DPrivate context.
+  Graphics2DPrivate& operator=(const Graphics2DPrivate& other);
+
+  /// Getter function for returning scale of the 2D graphics context.
+  float get_scale() const { return scale_; }
+
+ private:
+  float scale_;
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_PRIVATE_GRAPHICS_2D_PRIVATE_H_