Implement HiDPI support in Pepper dev interface

This patch requires WebKit patch https://bugs.webkit.org/show_bug.cgi?id=87874 (WebKit r121364)

Expose device_scale_factor and css_scale_factor to Pepper plugins via a dev
interface on View resource.
Allow Pepper plugins to create a 2D graphics context with a scale factor so the
plugins can render at device resolution rather than DIPs if they want.

BUG=114673
TEST=browser_tests --gtest_filter="PPAPITest.*" 
TEST=browser_tests --gtest_filter="OutOfProcessPPAPITest.*"
TEST=Build, run existing PPAPI plugin at 2x scale
TEST=Build, run test HiDPI aware plugin to render at device rez, at 1x, 2x scale

Review URL: https://chromiumcodereview.appspot.com/10544168

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@144773 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 131 insertions, 0 deletions

diff --git a/ppapi/c/dev/ppb_graphics_2d_dev.h b/ppapi/c/dev/ppb_graphics_2d_dev.h
new file mode 100644
index 0000000..a4661215
--- /dev/null
+++ b/ppapi/c/dev/ppb_graphics_2d_dev.h
@@ -0,0 +1,66 @@
+/* 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.
+ */
+
+/* From dev/ppb_graphics_2d_dev.idl modified Tue Jun 19 14:11:08 2012. */
+
+#ifndef PPAPI_C_DEV_PPB_GRAPHICS_2D_DEV_H_
+#define PPAPI_C_DEV_PPB_GRAPHICS_2D_DEV_H_
+
+#include "ppapi/c/pp_bool.h"
+#include "ppapi/c/pp_macros.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/pp_stdint.h"
+
+#define PPB_GRAPHICS2D_DEV_INTERFACE_0_1 "PPB_Graphics2D(Dev);0.1"
+#define PPB_GRAPHICS2D_DEV_INTERFACE PPB_GRAPHICS2D_DEV_INTERFACE_0_1
+
+/**
+ * @file
+ * This file contains the <code>PPB_Graphics2D_Dev</code> interface. */
+
+
+/**
+ * @addtogroup Interfaces
+ * @{
+ */
+/* PPB_Graphics2D_Dev interface */
+struct PPB_Graphics2D_Dev_0_1 {
+  /**
+   * 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] resource A <code>Graphics2D</code> context resource.
+   * @param[in] scale The scale to apply when painting.
+   *
+   * @return Returns <code>PP_TRUE</code> on success or <code>PP_FALSE</code> if
+   * the resource is invalid or the scale factor is 0 or less.
+   */
+  PP_Bool (*SetScale)(PP_Resource resource, float scale);
+  /***
+   * GetScale() gets the scale factor that will be applied when painting the
+   * graphics context onto the output device.
+   *
+   * @param[in] resource A <code>Graphics2D</code> context resource.
+   *
+   * @return Returns the scale factor for the graphics context. If the resource
+   * is not a valid <code>Graphics2D</code> context, this will return 0.0.
+   */
+  float (*GetScale)(PP_Resource resource);
+};
+
+typedef struct PPB_Graphics2D_Dev_0_1 PPB_Graphics2D_Dev;
+/**
+ * @}
+ */
+
+#endif  /* PPAPI_C_DEV_PPB_GRAPHICS_2D_DEV_H_ */
+
diff --git a/ppapi/c/dev/ppb_view_dev.h b/ppapi/c/dev/ppb_view_dev.h
new file mode 100644
index 0000000..1995193
--- /dev/null
+++ b/ppapi/c/dev/ppb_view_dev.h
@@ -0,0 +1,65 @@
+/* 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.
+ */
+
+/* From dev/ppb_view_dev.idl modified Mon Jun 18 14:55:58 2012. */
+
+#ifndef PPAPI_C_DEV_PPB_VIEW_DEV_H_
+#define PPAPI_C_DEV_PPB_VIEW_DEV_H_
+
+#include "ppapi/c/pp_macros.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/pp_stdint.h"
+
+#define PPB_VIEW_DEV_INTERFACE_0_1 "PPB_View(Dev);0.1"
+#define PPB_VIEW_DEV_INTERFACE PPB_VIEW_DEV_INTERFACE_0_1
+
+/**
+ * @file
+ * This file contains the <code>PPB_View_Dev</code> interface. */
+
+
+/**
+ * @addtogroup Interfaces
+ * @{
+ */
+/* PPB_View_Dev interface */
+struct PPB_View_Dev_0_1 {
+  /**
+   * GetDeviceScale returns the scale factor between device pixels and DIPs
+   * (also known as logical pixels or UI pixels on some platforms). This allows
+   * the developer to render their contents at device resolution, even as
+   * coordinates / sizes are given in DIPs through the API.
+   *
+   * Note that the coordinate system for Pepper APIs is DIPs. Also note that
+   * one DIP might not equal one CSS pixel - when page scale/zoom is in effect.
+   *
+   * @param[in] resource A <code>PP_Resource</code> corresponding to a
+   * <code>PPB_View</code> resource.
+   *
+   * @return A <code>float</code> value representing the number of device pixels
+   * per DIP. If the resource is invalid, the value will be 0.0.
+   */
+  float (*GetDeviceScale)(PP_Resource resource);
+  /**
+   * GetCSSScale returns the scale factor between DIPs and CSS pixels. This
+   * allows proper scaling between DIPs - as sent via the Pepper API - and CSS
+   * pixel coordinates used for Web content.
+   *
+   * @param[in] resource A <code>PP_Resource</code> corresponding to a
+   * <code>PPB_View</code> resource.
+   *
+   * @return css_scale A <code>float</code> value representing the number of
+   * DIPs per CSS pixel. If the resource is invalid, the value will be 0.0.
+   */
+  float (*GetCSSScale)(PP_Resource resource);
+};
+
+typedef struct PPB_View_Dev_0_1 PPB_View_Dev;
+/**
+ * @}
+ */
+
+#endif  /* PPAPI_C_DEV_PPB_VIEW_DEV_H_ */
+