[Reland] Fix ReadPixels from float fbo buffer in ES2/WebGL1.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index e8b9c3087c7b19827a6d7766345d63c161ba906d..fd688cf290519a478f28d15c2dc0bf35f6d9152e 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -1284,15 +1284,18 @@ class GLES2DecoderImpl : public GLES2Decoder, public ErrorStateClient {
   bool FormsTextureCopyingFeedbackLoop(TextureRef* texture, GLint level);
 
   // Check if a framebuffer meets our requirements.
+  // Generates |gl_error| if the framebuffer is incomplete.
   bool CheckFramebufferValid(
       Framebuffer* framebuffer,
       GLenum target,
       bool clear_uncleared_images,
+      GLenum gl_error,
       const char* func_name);
 
   bool CheckBoundDrawFramebufferValid(
       bool clear_uncleared_images, const char* func_name);
-  bool CheckBoundReadFramebufferValid(const char* func_name);
+  // Generates |gl_error| if the bound read fbo is incomplete.
+  bool CheckBoundReadFramebufferValid(const char* func_name, GLenum gl_error);
 
   // Checks if the current program exists and is valid. If not generates the
   // appropriate GL error.  Returns true if the current program is in a usable
@@ -3753,6 +3756,7 @@ bool GLES2DecoderImpl::CheckFramebufferValid(
     Framebuffer* framebuffer,
     GLenum target,
     bool clear_uncleared_images,
+    GLenum gl_error,
     const char* func_name) {
   if (!framebuffer) {
     if (surfaceless_)
@@ -3792,8 +3796,7 @@ bool GLES2DecoderImpl::CheckFramebufferValid(
 
   GLenum completeness = framebuffer->IsPossiblyComplete(feature_info_.get());
   if (completeness != GL_FRAMEBUFFER_COMPLETE) {
-    LOCAL_SET_GL_ERROR(
-        GL_INVALID_FRAMEBUFFER_OPERATION, func_name, "framebuffer incomplete");
+    LOCAL_SET_GL_ERROR(gl_error, func_name, "framebuffer incomplete");
     return false;
   }
 
@@ -3806,8 +3809,7 @@ bool GLES2DecoderImpl::CheckFramebufferValid(
       if (framebuffer->GetStatus(texture_manager(), target) !=
           GL_FRAMEBUFFER_COMPLETE) {
         LOCAL_SET_GL_ERROR(
-            GL_INVALID_FRAMEBUFFER_OPERATION, func_name,
-            "framebuffer incomplete (clear)");
+            gl_error, func_name, "framebuffer incomplete (clear)");
         return false;
       }
       ClearUnclearedAttachments(target, framebuffer);
@@ -3818,8 +3820,7 @@ bool GLES2DecoderImpl::CheckFramebufferValid(
     if (framebuffer->GetStatus(texture_manager(), target) !=
         GL_FRAMEBUFFER_COMPLETE) {
       LOCAL_SET_GL_ERROR(
-          GL_INVALID_FRAMEBUFFER_OPERATION, func_name,
-          "framebuffer incomplete (check)");
+          gl_error, func_name, "framebuffer incomplete (check)");
       return false;
     }
     framebuffer_manager()->MarkAsComplete(framebuffer);
@@ -3833,17 +3834,20 @@ bool GLES2DecoderImpl::CheckBoundDrawFramebufferValid(
       GL_DRAW_FRAMEBUFFER : GL_FRAMEBUFFER;
   Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
   bool valid = CheckFramebufferValid(
-      framebuffer, target, clear_uncleared_images, func_name);
+      framebuffer, target, clear_uncleared_images,
+      GL_INVALID_FRAMEBUFFER_OPERATION, func_name);
   if (valid && !features().chromium_framebuffer_multisample)
     OnUseFramebuffer();
   return valid;
 }
 
-bool GLES2DecoderImpl::CheckBoundReadFramebufferValid(const char* func_name) {
+bool GLES2DecoderImpl::CheckBoundReadFramebufferValid(
+    const char* func_name, GLenum gl_error) {
   GLenum target = features().chromium_framebuffer_multisample ?
       GL_READ_FRAMEBUFFER : GL_FRAMEBUFFER;
   Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
-  bool valid = CheckFramebufferValid(framebuffer, target, true, func_name);
+  bool valid = CheckFramebufferValid(
+      framebuffer, target, true, gl_error, func_name);
   return valid;
 }
 
@@ -5369,50 +5373,52 @@ void GLES2DecoderImpl::DoGenerateMipmap(GLenum target) {
 bool GLES2DecoderImpl::GetHelper(
     GLenum pname, GLint* params, GLsizei* num_written) {
   DCHECK(num_written);
-  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
-    switch (pname) {
-      case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
-        *num_written = 1;
-        // Return the GL implementation's preferred format and (see below type)
-        // if we have the GL extension that exposes this. This allows the GPU
-        // client to use the implementation's preferred format for glReadPixels
-        // for optimisation.
-        //
-        // A conflicting extension (GL_ARB_ES2_compatibility) specifies an error
-        // case when requested on integer/floating point buffers but which is
-        // acceptable on GLES2 and with the GL_OES_read_format extension.
-        //
-        // Therefore if an error occurs we swallow the error and use the
-        // internal implementation.
+  switch (pname) {
+    case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
+    case GL_IMPLEMENTATION_COLOR_READ_TYPE:
+      // They are not supported on Desktop GL until 4.1, but could be exposed
+      // through GL_OES_read_format extension. However, a conflicting extension
+      // GL_ARB_ES2_compatibility specifies an error case when requested on
+      // integer/floating point buffers.
+      // To simpify the handling, we just query and check for GL errors. If an
+      // GL error occur, we fall back to our internal implementation.
+      *num_written = 1;
+      if (!CheckBoundReadFramebufferValid("glGetIntegerv",
+                                          GL_INVALID_OPERATION)) {
         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::GetGLReadPixelsImplementationFormat(
-              GetBoundReadFrameBufferInternalFormat(),
-              GetBoundReadFrameBufferTextureType(),
-              feature_info_->feature_flags().ext_read_format_bgra);
+          *params = 0;
         }
         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;
+      }
+      if (params) {
+        ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
+                                           GetErrorState());
+        glGetIntegerv(pname, params);
+        if (glGetError() != GL_NO_ERROR) {
+          if (pname == GL_IMPLEMENTATION_COLOR_READ_FORMAT) {
+            *params = GLES2Util::GetGLReadPixelsImplementationFormat(
+                GetBoundReadFrameBufferInternalFormat(),
+                GetBoundReadFrameBufferTextureType(),
+                feature_info_->feature_flags().ext_read_format_bgra);
+          } else {
+            *params = GLES2Util::GetGLReadPixelsImplementationType(
+                GetBoundReadFrameBufferInternalFormat(),
+                GetBoundReadFrameBufferTextureType());
           }
-          *params = GLES2Util::GetGLReadPixelsImplementationType(
-              GetBoundReadFrameBufferInternalFormat(),
-              GetBoundReadFrameBufferTextureType());
         }
-        return true;
+        if (*params == GL_HALF_FLOAT &&
+            (feature_info_->context_type() == CONTEXT_TYPE_WEBGL1 ||
+             feature_info_->context_type() == CONTEXT_TYPE_OPENGLES2)) {
+          *params = GL_HALF_FLOAT_OES;
+        }
+      }
+      return true;
+    default:
+      break;
+  }
+
+  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
+    switch (pname) {
       case GL_MAX_FRAGMENT_UNIFORM_VECTORS:
         *num_written = 1;
         if (params) {
@@ -6788,7 +6794,8 @@ void GLES2DecoderImpl::DoBlitFramebufferCHROMIUM(
   DCHECK(!ShouldDeferReads() && !ShouldDeferDraws());
 
   if (!CheckBoundDrawFramebufferValid(true, "glBlitFramebufferCHROMIUM") ||
-      !CheckBoundReadFramebufferValid("glBlitFramebufferCHROMIUM")) {
+      !CheckBoundReadFramebufferValid("glBlitFramebufferCHROMIUM",
+                                      GL_INVALID_FRAMEBUFFER_OPERATION)) {
     return;
   }
 
@@ -9578,7 +9585,8 @@ error::Error GLES2DecoderImpl::HandleReadPixels(uint32_t immediate_data_size,
     return error::kNoError;
   }
 
-  if (!CheckBoundReadFramebufferValid("glReadPixels")) {
+  if (!CheckBoundReadFramebufferValid("glReadPixels",
+                                      GL_INVALID_FRAMEBUFFER_OPERATION)) {
     return error::kNoError;
   }
   GLenum src_internal_format = GetBoundReadFrameBufferInternalFormat();
@@ -9632,11 +9640,7 @@ error::Error GLES2DecoderImpl::HandleReadPixels(uint32_t immediate_data_size,
           case GL_HALF_FLOAT_OES:
           case GL_FLOAT:
           case GL_UNSIGNED_INT_10F_11F_11F_REV:
-            if (!feature_info_->IsES3Enabled()) {
-              accepted_types.push_back(GL_UNSIGNED_BYTE);
-            } else {
-              accepted_types.push_back(GL_FLOAT);
-            }
+            accepted_types.push_back(GL_FLOAT);
             break;
           default:
             accepted_types.push_back(GL_UNSIGNED_BYTE);
@@ -9674,6 +9678,10 @@ error::Error GLES2DecoderImpl::HandleReadPixels(uint32_t immediate_data_size,
         "format and type incompatible with the current read framebuffer");
     return error::kNoError;
   }
+  if (type == GL_HALF_FLOAT_OES &&
+      !(feature_info_->gl_version_info().is_es2)) {
+    type = GL_HALF_FLOAT;
+  }
   if (width == 0 || height == 0) {
     return error::kNoError;
   }
@@ -11794,7 +11802,8 @@ void GLES2DecoderImpl::DoCopyTexImage2D(
     return;
   }
 
-  if (!CheckBoundReadFramebufferValid("glCopyTexImage2D")) {
+  if (!CheckBoundReadFramebufferValid("glCopyTexImage2D",
+                                      GL_INVALID_FRAMEBUFFER_OPERATION)) {
     return;
   }
 
@@ -11993,7 +12002,8 @@ void GLES2DecoderImpl::DoCopyTexSubImage2D(
     return;
   }
 
-  if (!CheckBoundReadFramebufferValid("glCopyTexImage2D")) {
+  if (!CheckBoundReadFramebufferValid("glCopyTexImage2D",
+                                      GL_INVALID_FRAMEBUFFER_OPERATION)) {
     return;
   }