content/browser/renderer_host/compositing_iosurface_transformer_mac.h

   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_