PPAPI/NaCl: Make ImageData for NaCl just use shared memory

webkit/plugins/ppapi/ppb_image_data_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 WEBKIT_PLUGINS_PPAPI_PPB_IMAGE_DATA_IMPL_H_
 #define WEBKIT_PLUGINS_PPAPI_PPB_IMAGE_DATA_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ppapi/c/ppb_image_data.h"
 #include "ppapi/shared_impl/ppb_image_data_shared.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/thunk/ppb_image_data_api.h"
+#include "third_party/skia/include/core/SkCanvas.h"
 #include "webkit/plugins/ppapi/plugin_delegate.h"
 #include "webkit/plugins/webkit_plugins_export.h"
 
 namespace skia {
 class PlatformCanvas;
 }
 
 class SkBitmap;
 
 namespace webkit {
 namespace ppapi {
 
-class PPB_ImageData_Impl : public ::ppapi::Resource,
-                           public ::ppapi::PPB_ImageData_Shared,
-                           public ::ppapi::thunk::PPB_ImageData_API {
+class WEBKIT_PLUGINS_EXPORT PPB_ImageData_Impl
+    : public ::ppapi::Resource,
+      public ::ppapi::PPB_ImageData_Shared,
+      public NON_EXPORTED_BASE(::ppapi::thunk::PPB_ImageData_API) {
  public:
+  // We delegate most of our implementation to a back-end class that either uses
+  // a PlatformCanvas (for most trusted stuff) or bare shared memory (for use by
+  // NaCl). This makes it cheap & easy to implement Swap.
+  class Backend {
+   public:
+    virtual ~Backend() {};
+    virtual bool Init(PPB_ImageData_Impl* impl, PP_ImageDataFormat format,
+                      int width, int height, bool init_to_zero) = 0;
+    virtual bool IsMapped() const = 0;
+    virtual PluginDelegate::PlatformImage2D* PlatformImage() const = 0;
+    virtual void* Map() = 0;
+    virtual void Unmap() = 0;
+    virtual int32_t GetSharedMemory(int* handle, uint32_t* byte_count) = 0;
+    virtual skia::PlatformCanvas* GetPlatformCanvas() = 0;
+    virtual SkCanvas* GetCanvas() = 0;
+    virtual const SkBitmap* GetMappedBitmap() const = 0;
+  };
+
   // If you call this constructor, you must also call Init before use. Normally
   // you should use the static Create function, but this constructor is needed
   // for some internal uses of ImageData (like Graphics2D).
-  WEBKIT_PLUGINS_EXPORT explicit PPB_ImageData_Impl(PP_Instance instance);
+  enum ImageDataType { PLATFORM, NACL };
+  PPB_ImageData_Impl(PP_Instance instance, ImageDataType type);
   virtual ~PPB_ImageData_Impl();
 
-  static PP_Resource Create(PP_Instance pp_instance,
-                            PP_ImageDataFormat format,
-                            const PP_Size& size,
-                            PP_Bool init_to_zero);
+  bool Init(PP_ImageDataFormat format,
+            int width, int height,
+            bool init_to_zero);
 
-  WEBKIT_PLUGINS_EXPORT bool Init(PP_ImageDataFormat format,
-                                  int width, int height,
-                                  bool init_to_zero);
+  // Create an ImageData backed by a PlatformCanvas. You must use this if you
+  // intend the ImageData to be usable in platform-specific APIs (like font
+  // rendering or rendering widgets like scrollbars).
+  static PP_Resource CreatePlatform(PP_Instance pp_instance,
+                                    PP_ImageDataFormat format,
+                                    const PP_Size& size,
+                                    PP_Bool init_to_zero);
+
+  // Use this to create an ImageData for use with NaCl. This is backed by a
+  // simple shared memory buffer.
+  static PP_Resource CreateNaCl(PP_Instance pp_instance,
+                                PP_ImageDataFormat format,
+                                const PP_Size& size,
+                                PP_Bool init_to_zero);
 
   int width() const { return width_; }
   int height() const { return height_; }
 
   // Returns the image format.
   PP_ImageDataFormat format() const { return format_; }
 
   // Returns true if this image is mapped. False means that the image is either
   // invalid or not mapped. See ImageDataAutoMapper below.
-  bool is_mapped() const { return !!mapped_canvas_.get(); }
+  bool IsMapped() const;
+  PluginDelegate::PlatformImage2D* PlatformImage() const;
 
-  PluginDelegate::PlatformImage2D* platform_image() const {
-    return platform_image_.get();
-  }
-
+  // Resource override.
   virtual ::ppapi::thunk::PPB_ImageData_API* AsPPB_ImageData_API() OVERRIDE;
 
   // PPB_ImageData_API implementation.
   virtual PP_Bool Describe(PP_ImageDataDesc* desc) OVERRIDE;
   virtual void* Map() OVERRIDE;
   virtual void Unmap() OVERRIDE;
   virtual int32_t GetSharedMemory(int* handle, uint32_t* byte_count) OVERRIDE;
   virtual skia::PlatformCanvas* GetPlatformCanvas() OVERRIDE;
+  virtual SkCanvas* GetCanvas() OVERRIDE;
 
   const SkBitmap* GetMappedBitmap() const;
 
   // Swaps the guts of this image data with another.
   void Swap(PPB_ImageData_Impl* other);
 
  private:
+  PP_ImageDataFormat format_;
+  int width_;
+  int height_;
+  scoped_ptr<Backend> backend_;
+
+  DISALLOW_COPY_AND_ASSIGN(PPB_ImageData_Impl);
+};
+
+class ImageDataPlatformBackend : public PPB_ImageData_Impl::Backend {
+ public:
+  ImageDataPlatformBackend();
+  virtual ~ImageDataPlatformBackend();
+
+  // PPB_ImageData_Impl::Backend implementation.
+  virtual bool Init(PPB_ImageData_Impl* impl, PP_ImageDataFormat format,
+                    int width, int height, bool init_to_zero) OVERRIDE;
+  virtual bool IsMapped() const OVERRIDE;
+  virtual PluginDelegate::PlatformImage2D* PlatformImage() const OVERRIDE;
+  virtual void* Map() OVERRIDE;
+  virtual void Unmap() OVERRIDE;
+  virtual int32_t GetSharedMemory(int* handle, uint32_t* byte_count) OVERRIDE;
+  virtual skia::PlatformCanvas* GetPlatformCanvas() OVERRIDE;
+  virtual SkCanvas* GetCanvas() OVERRIDE;
+  virtual const SkBitmap* GetMappedBitmap() const OVERRIDE;
+
+ private:
   // This will be NULL before initialization, and if this PPB_ImageData_Impl is
   // swapped with another.
   scoped_ptr<PluginDelegate::PlatformImage2D> platform_image_;
 
   // When the device is mapped, this is the image. Null when umapped.
   scoped_ptr<skia::PlatformCanvas> mapped_canvas_;
 
-  PP_ImageDataFormat format_;
-  int width_;
-  int height_;
+  DISALLOW_COPY_AND_ASSIGN(ImageDataPlatformBackend);
+};
 
-  DISALLOW_COPY_AND_ASSIGN(PPB_ImageData_Impl);
+class ImageDataNaClBackend : public PPB_ImageData_Impl::Backend {
+ public:
+  ImageDataNaClBackend();
+  virtual ~ImageDataNaClBackend();
+
+  // PPB_ImageData_Impl::Backend implementation.
+  bool Init(PPB_ImageData_Impl* impl, PP_ImageDataFormat format,
+            int width, int height, bool init_to_zero) OVERRIDE;
+  virtual bool IsMapped() const OVERRIDE;
+  PluginDelegate::PlatformImage2D* PlatformImage() const OVERRIDE;
+  virtual void* Map() OVERRIDE;
+  virtual void Unmap() OVERRIDE;
+  virtual int32_t GetSharedMemory(int* handle, uint32_t* byte_count) OVERRIDE;
+  virtual skia::PlatformCanvas* GetPlatformCanvas() OVERRIDE;
+  virtual SkCanvas* GetCanvas() OVERRIDE;
+  virtual const SkBitmap* GetMappedBitmap() const OVERRIDE;
+
+ private:
+  scoped_ptr<base::SharedMemory> shared_memory_;
+  // skia_bitmap_ is backed by shared_memory_.
+  SkBitmap skia_bitmap_;
+  SkCanvas skia_canvas_;
+  uint32 map_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImageDataNaClBackend);
 };
 
 // Manages mapping an image resource if necessary. Use this to ensure the
 // image is mapped. The destructor will put the image back into the previous
 // state. You must check is_valid() to make sure the image was successfully
 // mapped before using it.
 //
 // Example:
 //   ImageDataAutoMapper mapper(image_data);
 //   if (!mapper.is_valid())
 //     return utter_failure;
 //   image_data->mapped_canvas()->blah();  // Guaranteed valid.
 class ImageDataAutoMapper {
  public:
   explicit ImageDataAutoMapper(PPB_ImageData_Impl* image_data)
         : image_data_(image_data) {
-    if (image_data_->is_mapped()) {
+    if (image_data_->IsMapped()) {
       is_valid_ = true;
       needs_unmap_ = false;
     } else {
       is_valid_ = needs_unmap_ = !!image_data_->Map();
     }
   }
 
   ~ImageDataAutoMapper() {
     if (needs_unmap_)
       image_data_->Unmap();
   }
 
   // Check this to see if the image was successfully mapped. If this is false,
   // the image could not be mapped and is unusable.
   bool is_valid() const { return is_valid_; }
 
  private:
   PPB_ImageData_Impl* image_data_;
   bool is_valid_;
   bool needs_unmap_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDataAutoMapper);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPB_IMAGE_DATA_IMPL_H_