Home | History | Annotate | Download | only in renderer_host 
      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_TRANSFORMER_MAC_H_
      6 #define CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_TRANSFORMER_MAC_H_
      7 
      8 #include <OpenGL/gl.h>
      9 
     10 #include "base/basictypes.h"
     11 #include "content/browser/renderer_host/compositing_iosurface_shader_programs_mac.h"
     12 #include "ui/gfx/size.h"
     13 
     14 namespace gfx {
     15 class Rect;
     16 }  // namespace gfx
     17 
     18 namespace content {
     19 
     20 // Provides useful image filtering operations that are implemented efficiently
     21 // using OpenGL shader programs.
     22 //
     23 // Note: All methods assume to be called within an active OpenGL context.
     24 class CompositingIOSurfaceTransformer {
     25  public:
     26   // Construct a transformer that always uses the given parameters for texture
     27   // bindings.  |texture_target| is one of the valid enums to use with
     28   // glBindTexture().
     29   // |src_texture_needs_y_flip| is true when the |src_texture| argument to any
     30   // of the methods below uses upside-down Y coordinates.
     31   // |shader_program_cache| is not owned by this instance.
     32   CompositingIOSurfaceTransformer(
     33       GLenum texture_target, bool src_texture_needs_y_flip,
     34       CompositingIOSurfaceShaderPrograms* shader_program_cache);
     35 
     36   ~CompositingIOSurfaceTransformer();
     37 
     38   // Delete any references to currently-cached OpenGL objects.  This must be
     39   // called within the OpenGL context just before destruction.
     40   void ReleaseCachedGLObjects();
     41 
     42   // Resize using bilinear interpolation.  Returns false on error.  Otherwise,
     43   // the |texture| argument will point to the result.  Ownership of the returned
     44   // |texture| remains with CompositingIOSurfaceTransformer (i.e., the caller
     45   // must not delete this texture).  The |texture| remains valid until the next
     46   // call to ResizeBilinear() or ReleaseCachedGLObjects().
     47   //
     48   // If the src and dst sizes are identical, this becomes a simple copy into a
     49   // new texture.
     50   //
     51   // Note: This implementation is faulty in that minifications by more than 2X
     52   // will undergo aliasing.
     53   bool ResizeBilinear(GLuint src_texture, const gfx::Rect& src_subrect,
     54                       const gfx::Size& dst_size, GLuint* texture);
     55 
     56   // Color format conversion from RGB to planar YV12 (also known as YUV420).
     57   //
     58   // YV12 is effectively a twelve bit per pixel format consisting of a full-
     59   // size y (luminance) plane and half-width, half-height u and v (blue and
     60   // red chrominance) planes.  This method will return three off-screen
     61   // textures, one for each plane, via the output arguments |texture_y|,
     62   // |texture_u|, and |texture_v|.  While the textures are in GL_RGBA format,
     63   // they should be interpreted as the appropriate single-byte, planar format
     64   // after reading the pixel data.  The output arguments |packed_y_size| and
     65   // |packed_uv_size| follow from these special semantics: They represent the
     66   // size of their corresponding texture, if it was to be treated like RGBA
     67   // pixel data.  That means their widths are in terms of "quads," where one
     68   // quad contains 4 Y (or U or V) pixels.
     69   //
     70   // Ownership of the returned textures remains with
     71   // CompositingIOSurfaceTransformer (i.e., the caller must not delete the
     72   // textures).  The textures remain valid until the next call to
     73   // TransformRGBToYV12() or ReleaseCachedGLObjects().
     74   //
     75   // If |src_subrect|'s size does not match |dst_size|, the source will be
     76   // bilinearly interpolated during conversion.
     77   //
     78   // Returns true if successful, and the caller is responsible for deleting the
     79   // output textures.
     80   bool TransformRGBToYV12(
     81       GLuint src_texture, const gfx::Rect& src_subrect,
     82       const gfx::Size& dst_size,
     83       GLuint* texture_y, GLuint* texture_u, GLuint* texture_v,
     84       gfx::Size* packed_y_size, gfx::Size* packed_uv_size);
     85 
     86  private:
     87   enum CachedTexture {
     88     RGBA_OUTPUT = 0,
     89     Y_PLANE_OUTPUT,
     90     UUVV_INTERMEDIATE,
     91     U_PLANE_OUTPUT,
     92     V_PLANE_OUTPUT,
     93     NUM_CACHED_TEXTURES
     94   };
     95 
     96   // If necessary, generate the texture and/or resize it to the given |size|.
     97   void PrepareTexture(CachedTexture which, const gfx::Size& size);
     98 
     99   // If necessary, generate a framebuffer object to be used as an intermediate
    100   // destination for drawing.
    101   void PrepareFramebuffer();
    102 
    103   // Target to bind all input and output textures to (which defines the type of
    104   // textures being created and read).  Generally, this is
    105   // GL_TEXTURE_RECTANGLE_ARB.
    106   const GLenum texture_target_;
    107   const bool src_texture_needs_y_flip_;
    108   CompositingIOSurfaceShaderPrograms* const shader_program_cache_;
    109 
    110   // Cached OpenGL objects.
    111   GLuint textures_[NUM_CACHED_TEXTURES];
    112   gfx::Size texture_sizes_[NUM_CACHED_TEXTURES];
    113   GLuint frame_buffer_;
    114 
    115   // Auto-detected and set once in the constructor.
    116   bool system_supports_multiple_draw_buffers_;
    117 
    118   DISALLOW_COPY_AND_ASSIGN(CompositingIOSurfaceTransformer);
    119 };
    120 
    121 }  // namespace content
    122 
    123 #endif  // CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_TRANSFORMER_MAC_H_
    124