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
   8 namespace content {
   9
  10 GLHelperReadbackSupport::GLHelperReadbackSupport(gpu::gles2::GLES2Interface* gl)
  11     : gl_(gl) {
  12   InitializeReadbackSupport();
  13 }
  14
  15 GLHelperReadbackSupport::~GLHelperReadbackSupport() {}
  16
  17 void GLHelperReadbackSupport::InitializeReadbackSupport() {
  18   // We are concerned about 16, 32-bit formats only.
  19   // The below are the most used 16, 32-bit formats.
  20   // In future if any new format support is needed that should be added here.
  21   // Initialize the array with FORMAT_NOT_SUPPORTED as we dont know the
  22   // supported formats yet.
  23   for (int i = 0; i <= kLastEnum_SkColorType; ++i) {
  24     format_support_table_[i] = FORMAT_NOT_SUPPORTED;
  25   }
  26   CheckForReadbackSupport(kRGB_565_SkColorType);
  27   CheckForReadbackSupport(kARGB_4444_SkColorType);
  28   CheckForReadbackSupport(kN32_SkColorType);
  29   // Further any formats, support should be checked here.
  30 }
  31
  32 void GLHelperReadbackSupport::CheckForReadbackSupport(
  33     SkColorType texture_format) {
  34   bool supports_format = false;
  35   switch (texture_format) {
  36     case kRGB_565_SkColorType:
  37       supports_format = SupportsFormat(GL_RGB, GL_UNSIGNED_SHORT_5_6_5);
  38       break;
  39     case kN32_SkColorType:
  40       // This is the baseline, assume always true.
  41       supports_format = true;
  42       break;
  43     case kARGB_4444_SkColorType:
  44       supports_format = false;
  45       break;
  46     default:
  47       NOTREACHED();
  48       supports_format = false;
  49       break;
  50   }
  51   DCHECK((int)texture_format <= (int)kLastEnum_SkColorType);
  52   format_support_table_[texture_format] =
  53       supports_format ? FORMAT_SUPPORTED : FORMAT_NOT_SUPPORTED;
  54 }
  55
  56 void GLHelperReadbackSupport::GetAdditionalFormat(GLint format, GLint type,
  57                                                   GLint *format_out,
  58                                                   GLint *type_out) {
  59   for (unsigned int i = 0; i < format_cache_.size(); i++) {
  60     if (format_cache_[i].format == format && format_cache_[i].type == type) {
  61       *format_out = format_cache_[i].read_format;
  62       *type_out = format_cache_[i].read_type;
  63       return;
  64     }
  65   }
  66
  67   const int kTestSize = 64;
  68   content::ScopedTexture dst_texture(gl_);
  69   ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, dst_texture);
  70   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  71   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  72   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  73   gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  74   gl_->TexImage2D(
  75       GL_TEXTURE_2D, 0, format, kTestSize, kTestSize, 0, format, type, NULL);
  76   ScopedFramebuffer dst_framebuffer(gl_);
  77   ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(gl_,
  78                                                              dst_framebuffer);
  79   gl_->FramebufferTexture2D(
  80       GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, dst_texture, 0);
  81   gl_->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, format_out);
  82   gl_->GetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, type_out);
  83
  84   struct FormatCacheEntry entry = { format, type, *format_out, *type_out };
  85   format_cache_.push_back(entry);
  86 }
  87
  88 bool GLHelperReadbackSupport::SupportsFormat(GLint format, GLint type) {
  89   // GLES2.0 Specification says this pairing is always supported
  90   // with additional format from GL_IMPLEMENTATION_COLOR_READ_FORMAT/TYPE
  91   if (format == GL_RGBA && type == GL_UNSIGNED_BYTE)
  92     return true;
  93   bool supports_format = false;
  94   GLint ext_format = 0, ext_type = 0;
  95   GetAdditionalFormat(format, type, &ext_format, &ext_type);
  96   if ((ext_format == format) && (ext_type == type)) {
  97     supports_format = true;
  98   }
  99   return supports_format;
 100 }
 101
 102 bool GLHelperReadbackSupport::IsReadbackConfigSupported(
 103     SkColorType texture_format) {
 104   switch (format_support_table_[texture_format]) {
 105     case FORMAT_SUPPORTED:
 106       return true;
 107     case FORMAT_NOT_SUPPORTED:
 108       return false;
 109     default:
 110       NOTREACHED();
 111       return false;
 112   }
 113 }
 114
 115 }  // namespace content