content/common/gpu/client/gl_helper_readback_support.cc

   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 #include "content/common/gpu/client/gl_helper_readback_support.h"
   6 #include "base/logging.h"
   7 #include "gpu/GLES2/gl2extchromium.h"
   8 #include "third_party/skia/include/core/SkImageInfo.h"
   9
  10 namespace content {
  11
  12 GLHelperReadbackSupport::GLHelperReadbackSupport(gpu::gles2::GLES2Interface* gl)
  13     : gl_(gl) {
  14   InitializeReadbackSupport();
  15 }
  16
  17 GLHelperReadbackSupport::~GLHelperReadbackSupport() {}
  18
  19 void GLHelperReadbackSupport::InitializeReadbackSupport() {
  20   // We are concerned about 16, 32-bit formats only.  The below are the most
  21   // used 16, 32-bit formats.  In future if any new format support is needed
  22   // that should be added here.  Initialize the array with
  23   // GLHelperReadbackSupport::NOT_SUPPORTED as we dont know the supported
  24   // formats yet.
  25   for (int i = 0; i <= kLastEnum_SkColorType; ++i) {
  26     format_support_table_[i] = GLHelperReadbackSupport::NOT_SUPPORTED;
  27   }
  28   CheckForReadbackSupport(kRGB_565_SkColorType);
  29   CheckForReadbackSupport(kARGB_4444_SkColorType);
  30   CheckForReadbackSupport(kRGBA_8888_SkColorType);
  31   CheckForReadbackSupport(kBGRA_8888_SkColorType);
  32   // Further any formats, support should be checked here.
  33 }
  34
  35 void GLHelperReadbackSupport::CheckForReadbackSupport(
  36     SkColorType texture_format) {
  37   bool supports_format = false;
  38   switch (texture_format) {
  39     case kRGB_565_SkColorType:
  40       supports_format = SupportsFormat(GL_RGB, GL_UNSIGNED_SHORT_5_6_5);
  41       break;
  42     case kRGBA_8888_SkColorType:
  43       // This is the baseline, assume always true.
  44       supports_format = true;
  45       break;
  46     case kBGRA_8888_SkColorType:
  47       supports_format = SupportsFormat(GL_BGRA_EXT, GL_UNSIGNED_BYTE);
  48       break;
  49     case kARGB_4444_SkColorType:
  50       supports_format = false;
  51       break;
  52     default:
  53       NOTREACHED();
  54       supports_format = false;
  55       break;
  56   }
  57   DCHECK((int)texture_format <= (int)kLastEnum_SkColorType);
  58   format_support_table_[texture_format] =
  59       supports_format ? GLHelperReadbackSupport::SUPPORTED
  60                       : GLHelperReadbackSupport::NOT_SUPPORTED;
  61 }
  62
  63 void GLHelperReadbackSupport::GetAdditionalFormat(GLenum format,
  64                                                   GLenum type,
  65                                                   GLenum* format_out,
  66                                                   GLenum* type_out) {
  67   for (unsigned int i = 0; i < format_cache_.size(); i++) {
  68     if (format_cache_[i].format == format && format_cache_[i].type == type) {
  69       *format_out = format_cache_[i].read_format;
  70       *type_out = format_cache_[i].read_type;
  71       return;
  72     }
  73   }
  74
  75   const int kTestSize = 64;
  76   content::ScopedTexture dst_texture(gl_);
  77   ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, dst_texture);
  78   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  79   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  80   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  81   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  82   gl_->TexImage2D(
  83       GL_TEXTURE_2D, 0, format, kTestSize, kTestSize, 0, format, type, NULL);
  84   ScopedFramebuffer dst_framebuffer(gl_);
  85   ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(gl_,
  86                                                              dst_framebuffer);
  87   gl_->FramebufferTexture2D(
  88       GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, dst_texture, 0);
  89   GLint format_tmp = 0, type_tmp = 0;
  90   gl_->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &format_tmp);
  91   gl_->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &type_tmp);
  92   *format_out = format_tmp;
  93   *type_out = type_tmp;
  94
  95   struct FormatCacheEntry entry = { format, type, *format_out, *type_out };
  96   format_cache_.push_back(entry);
  97 }
  98
  99 bool GLHelperReadbackSupport::SupportsFormat(GLenum format, GLenum type) {
 100   // GLES2.0 Specification says this pairing is always supported
 101   // with additional format from GL_IMPLEMENTATION_COLOR_READ_FORMAT/TYPE
 102   if (format == GL_RGBA && type == GL_UNSIGNED_BYTE)
 103     return true;
 104
 105   if (format == GL_BGRA_EXT && type == GL_UNSIGNED_BYTE) {
 106     const GLubyte* tmp = gl_->GetString(GL_EXTENSIONS);
 107     std::string extensions =
 108         " " + std::string(reinterpret_cast<const char*>(tmp)) + " ";
 109     if (extensions.find(" GL_EXT_read_format_bgra ") != std::string::npos) {
 110       return true;
 111     }
 112   }
 113
 114   bool supports_format = false;
 115   GLenum ext_format = 0, ext_type = 0;
 116   GetAdditionalFormat(format, type, &ext_format, &ext_type);
 117   if ((ext_format == format) && (ext_type == type)) {
 118     supports_format = true;
 119   }
 120   return supports_format;
 121 }
 122
 123 GLHelperReadbackSupport::FormatSupport
 124 GLHelperReadbackSupport::GetReadbackConfig(SkColorType color_type,
 125                                            bool can_swizzle,
 126                                            GLenum* format,
 127                                            GLenum* type,
 128                                            size_t* bytes_per_pixel) {
 129   DCHECK(format && type && bytes_per_pixel);
 130   *bytes_per_pixel = 4;
 131   *type = GL_UNSIGNED_BYTE;
 132   GLenum new_format = 0, new_type = 0;
 133   switch (color_type) {
 134     case kRGB_565_SkColorType:
 135       if (format_support_table_[color_type] ==
 136           GLHelperReadbackSupport::SUPPORTED) {
 137         *format = GL_RGB;
 138         *type = GL_UNSIGNED_SHORT_5_6_5;
 139         *bytes_per_pixel = 2;
 140         return GLHelperReadbackSupport::SUPPORTED;
 141       }
 142       break;
 143     case kRGBA_8888_SkColorType:
 144       *format = GL_RGBA;
 145       if (can_swizzle) {
 146         // If GL_BGRA_EXT is advertised as the readback format through
 147         // GL_IMPLEMENTATION_COLOR_READ_FORMAT then assume it is preferred by
 148         // the implementation for performance.
 149         GetAdditionalFormat(*format, *type, &new_format, &new_type);
 150
 151         if (new_format == GL_BGRA_EXT && new_type == GL_UNSIGNED_BYTE) {
 152           *format = GL_BGRA_EXT;
 153           return GLHelperReadbackSupport::SWIZZLE;
 154         }
 155       }
 156       return GLHelperReadbackSupport::SUPPORTED;
 157     case kBGRA_8888_SkColorType:
 158       *format = GL_BGRA_EXT;
 159       if (format_support_table_[color_type] ==
 160           GLHelperReadbackSupport::SUPPORTED)
 161         return GLHelperReadbackSupport::SUPPORTED;
 162
 163       if (can_swizzle) {
 164         *format = GL_RGBA;
 165         return GLHelperReadbackSupport::SWIZZLE;
 166       }
 167
 168       break;
 169     case kARGB_4444_SkColorType:
 170       return GLHelperReadbackSupport::NOT_SUPPORTED;
 171     default:
 172       NOTREACHED();
 173       break;
 174   }
 175
 176   return GLHelperReadbackSupport::NOT_SUPPORTED;
 177 }
 178
 179 }  // namespace content