Make the Pepper proxy support in-process font rendering.

ppapi/shared_impl/font_impl.h

+// Copyright (c) 2011 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_SHARED_IMPL_FONT_IMPL_H_
+#define PPAPI_SHARED_IMPL_FONT_IMPL_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
+#include "ppapi/c/pp_bool.h"
+#include "ppapi/c/pp_stdint.h"
+
+struct PP_FontDescription_Dev;
+struct PP_FontMetrics_Dev;
+struct PP_Point;
+struct PP_Rect;
+
+namespace base {
+class WaitableEvent;
+}
+
+namespace skia {
+class PlatformCanvas;
+}  // namespace skia
+
+namespace WebKit {
+class WebFont;
+}  // namespace WebKit
+
+namespace pp {
+namespace shared_impl {
+
+// This class is a bit subtle. It's designed to be used in two contexts:
+//  - In the renderer in the same thread as WebKit.
+//  - On a special WebKit thread in the plugin process.
+// As a result, the actual implementation is provided in terms of functions
+// prefixed by "Do" that don't depend on any global Pepper state, and that
+// supply the return values via output parameters (for the other-thread case).
+// Each implementation is then in charge of setting up the call appropriately.
+//
+// The Do* functions take an optional waitable event. If provided, this
+// event will be signaled when the function completes. This allows the
+// cross-thread implementation to know when the function completes.
+class FontImpl {
+ public:
+  // C++ version of PP_TextRun_Dev. Since the Do* functions will be called on
+  // an alternate thread in the proxy, and since there are different methods
+  // of converting PP_Var -> strings in the plugin and the proxy, we can't
+  // use PP_Vars in the Do* funcitons below.

[piman, 2011/05/09 20:13:44]

funcitons->functions

+  struct TextRun {
+    std::string text;
+    bool rtl;
+    bool override_direction;
+  };
+
+  FontImpl();
+  virtual ~FontImpl();
+
+  // Validates the parameters in thee description. Can be called on any thread.
+  static bool IsPPFontDescriptionValid(const PP_FontDescription_Dev& desc);
+
+ protected:
+  // DoDrawText takes too many arguments to be used with base::Bind, so we
+  // use this struct to hold them.
+  struct DrawTextParams {
+    DrawTextParams(skia::PlatformCanvas* destination_arg,
+                   const TextRun& text_arg,
+                   const PP_Point* position_arg,

[piman, 2011/05/09 20:13:44]

Can we make position a const & as well, for consistency ?

[brettw, 2011/05/09 21:00:35]

My internal functions match the PPAPI functions, which is why I use the pointers
here. The TextRun is a ref because it's internal to this class and made at the
call site.

+                   uint32_t color_arg,
+                   const PP_Rect* clip_arg,
+                   bool image_data_is_opaque_arg);
+    ~DrawTextParams();
+
+    skia::PlatformCanvas* destination;
+    const TextRun& text;
+    const PP_Point* position;
+    uint32_t color;
+    const PP_Rect* clip;
+    bool image_data_is_opaque;
+  };
+
+  // The face name from the description is given in desc_face so we can avoid
+  // a dependency on var conversion. See class description for waitable_event
+  // documentation.
+  void DoCreate(base::WaitableEvent* event,
+                const PP_FontDescription_Dev& desc,
+                const std::string& desc_face);
+
+  // The face name in the description is not filled in to avoid a dependency
+  // on creating vars. Instead, the face name is placed into the given string.
+  // See class description for waitable_event documentation.
+  void DoDescribe(base::WaitableEvent* event,
+                  PP_FontDescription_Dev* description,
+                  std::string* face,
+                  PP_FontMetrics_Dev* metrics,
+                  PP_Bool* result);
+  void DoDrawTextAt(base::WaitableEvent* event,
+                    const DrawTextParams& params);
+  void DoMeasureText(base::WaitableEvent* event,
+                     const TextRun& text, int32_t* result);
+  void DoCharacterOffsetForPixel(base::WaitableEvent* event,
+                                 const TextRun& text,
+                                 int32_t pixel_position,
+                                 uint32_t* result);
+  void DoPixelOffsetForCharacter(base::WaitableEvent* event,
+                                 const TextRun& text,
+                                 uint32_t char_offset,
+                                 int32_t* result);
+
+  // Access only on the WebKit thread.
+  scoped_ptr<WebKit::WebFont> font_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FontImpl);
+};
+
+}  // namespace shared_impl
+}  // namespace pp
+
+#endif  // PPAPI_SHARED_IMPL_FONT_IMPL_H_