Fix ReadPixels implementation specific read format/type on desktop GL.

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 5048 matching lines @@
         // Therefore if an error occurs we swallow the error and use the
         // internal implementation.
         if (params) {
           if (context_->HasExtension("GL_OES_read_format")) {
             ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                                GetErrorState());
             glGetIntegerv(pname, params);
             if (glGetError() == GL_NO_ERROR)
               return true;
           }
-          *params = GLES2Util::GetPreferredGLReadPixelsFormat(
-              GetBoundReadFrameBufferInternalFormat());
+          GLES2Util::TargetESVersion target_es_version =
+              feature_info_->IsES3Enabled() ? GLES2Util::kES3 : GLES2Util::kES2;
+          *params = GLES2Util::GetGLReadPixelsImplementationFormat(
+              GetBoundReadFrameBufferInternalFormat(), target_es_version);
         }
         return true;
       case GL_IMPLEMENTATION_COLOR_READ_TYPE:
         *num_written = 1;
         if (params) {
           if (context_->HasExtension("GL_OES_read_format")) {
             ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                                GetErrorState());
             glGetIntegerv(pname, params);
             if (glGetError() == GL_NO_ERROR)
               return true;
           }
-          *params = GLES2Util::GetPreferredGLReadPixelsType(
+          GLES2Util::TargetESVersion target_es_version =
+              feature_info_->IsES3Enabled() ? GLES2Util::kES3 : GLES2Util::kES2;
+          *params = GLES2Util::GetGLReadPixelsImplementationType(
               GetBoundReadFrameBufferInternalFormat(),
-              GetBoundReadFrameBufferTextureType());
+              GetBoundReadFrameBufferTextureType(),
+              target_es_version);
         }
         return true;
       case GL_MAX_FRAGMENT_UNIFORM_VECTORS:
         *num_written = 1;
         if (params) {
           *params = group_->max_fragment_uniform_vectors();
         }
         return true;
       case GL_MAX_VARYING_VECTORS:
         *num_written = 1;
@@ skipping 3649 matching lines @@
 
   GLenum src_internal_format = GetBoundReadFrameBufferInternalFormat();
   if (src_internal_format == 0) {
     LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glReadPixels",
         "no valid read buffer source");
     return error::kNoError;
   }
   std::vector<GLenum> accepted_formats;
   std::vector<GLenum> accepted_types;
   switch (src_internal_format) {
-    case GL_RGB10_A2UI:
-      accepted_formats.push_back(GL_RGBA);
-      accepted_types.push_back(GL_UNSIGNED_INT_2_10_10_10_REV);
     case GL_R8UI:
     case GL_R16UI:
     case GL_R32UI:
     case GL_RG8UI:
     case GL_RG16UI:
     case GL_RG32UI:
     // All the RGB_INTEGER formats are not renderable.
     case GL_RGBA8UI:
+    case GL_RGB10_A2UI:
     case GL_RGBA16UI:
     case GL_RGBA32UI:
       accepted_formats.push_back(GL_RGBA_INTEGER);
       accepted_types.push_back(GL_UNSIGNED_INT);
       break;
     case GL_R8I:
     case GL_R16I:
     case GL_R32I:
     case GL_RG8I:
     case GL_RG16I:
     case GL_RG32I:
     case GL_RGBA8I:
     case GL_RGBA16I:
     case GL_RGBA32I:
       accepted_formats.push_back(GL_RGBA_INTEGER);
       accepted_types.push_back(GL_INT);
       break;
+    case GL_RGB10_A2:
+      accepted_formats.push_back(GL_RGBA);
+      accepted_types.push_back(GL_UNSIGNED_BYTE);
+      // Special case with an extra supported format/type.
+      accepted_formats.push_back(GL_RGBA);
+      accepted_types.push_back(GL_UNSIGNED_INT_2_10_10_10_REV);
+      break;
     default:
       accepted_formats.push_back(GL_RGBA);
       {
         GLenum src_type = GetBoundReadFrameBufferTextureType();
         switch (src_type) {
           case GL_HALF_FLOAT:
           case GL_HALF_FLOAT_OES:
           case GL_FLOAT:
           case GL_UNSIGNED_INT_10F_11F_11F_REV:
-            accepted_types.push_back(GL_FLOAT);
+            if (!feature_info_->IsES3Enabled()) {
+              accepted_types.push_back(GL_UNSIGNED_BYTE);
+            } else {
+              accepted_types.push_back(GL_FLOAT);
+            }

[Ken Russell (switch to Gerrit), 2015/08/27 01:45:45]

I'm having difficulty understanding how the earlier code worked. It doesn't look
to me like it would advertise support for reading back RGBA/UNSIGNED_BYTE if a
floating-point framebuffer were bound -- but that would have broken the
conformance/extensions/oes-texture-float.html test.

[Zhenyao Mo, 2015/08/27 03:13:31]

It turned out we never tested RGBA/UNSIGNED_BYTE read back with float/half_float
textures in WebGL 1.  That's why the bug is never caught.

             break;
           default:
             accepted_types.push_back(GL_UNSIGNED_BYTE);
             break;
         }
       }
       break;
   }
   if (!IsWebGLContext()) {
     accepted_formats.push_back(GL_BGRA_EXT);
@@ skipping 6251 matching lines @@
   return error::kNoError;
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu