content/common/gpu/client/gl_helper_readback_support.h

   1 // Copyright 2014 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_COMMON_GPU_CLIENT_GL_HELPER_READBACK_SUPPORT_H_
   6 #define CONTENT_COMMON_GPU_CLIENT_GL_HELPER_READBACK_SUPPORT_H_
   7
   8 #include <vector>
   9
  10 #include "content/common/gpu/client/gl_helper.h"
  11
  12 namespace content {
  13
  14 class CONTENT_EXPORT GLHelperReadbackSupport {
  15  public:
  16   GLHelperReadbackSupport(gpu::gles2::GLES2Interface* gl);
  17
  18   ~GLHelperReadbackSupport();
  19
  20   // Checks whether the readback (Color read format and type) is supported
  21   // for the requested texture format  by the hardware or not.
  22   // For ex: some hardwares have rgb565 readback
  23   // support when binded with the frame buffer for others it may fail.
  24   // Here we pass the internal textureformat as skia config.
  25   bool IsReadbackConfigSupported(SkColorType texture_format);
  26
  27   // Provides the additional readback format/type pairing for a render target
  28   // of a given format/type pairing
  29   void GetAdditionalFormat(GLint format, GLint type, GLint *format_out,
  30                            GLint *type_out);
  31  private:
  32   enum FormatSupport { FORMAT_NOT_SUPPORTED = 0, FORMAT_SUPPORTED, };
  33
  34   struct FormatCacheEntry {
  35     GLint format;
  36     GLint type;
  37     GLint read_format;
  38     GLint read_type;
  39   };
  40
  41   // This populates the format_support_table with the list of supported
  42   // formats.
  43   void InitializeReadbackSupport();
  44
  45   // This api is called  once per format and it is done in the
  46   // InitializeReadbackSupport. We should not use this any where
  47   // except the InitializeReadbackSupport.Calling this at other places
  48   // can distrub the state of normal gl operations.
  49   void CheckForReadbackSupport(SkColorType texture_format);
  50
  51   // Helper functions for checking the supported texture formats.
  52   // Avoid using this API in between texture operations, as this does some
  53   // teture opertions (bind, attach) internally.
  54   bool SupportsFormat(GLint format, GLint type);
  55
  56   FormatSupport format_support_table_[kLastEnum_SkColorType + 1];
  57
  58   gpu::gles2::GLES2Interface* gl_;
  59   std::vector<struct FormatCacheEntry> format_cache_;
  60 };
  61
  62 }  // namespace content
  63
  64 #endif  // CONTENT_COMMON_GPU_CLIENT_GL_HELPER_READBACK_SUPPORT_H_