Determine WebGL back-buffer on Mali-400 GPU

Source/core/html/canvas/WebGLRenderingContextBase.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1437 matching lines @@
     if (isContextLost())
         return;
     m_clearStencil = s;
     webContext()->clearStencil(s);
 }
 
 void WebGLRenderingContextBase::colorMask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha)
 {
     if (isContextLost())
         return;
+    if (!m_requestedAttributes.alpha() && !drawingBuffer()->isRGBTextureSupported())
+        alpha = GL_FALSE;
+
     m_colorMask[0] = red;
     m_colorMask[1] = green;
     m_colorMask[2] = blue;
     m_colorMask[3] = alpha;
     webContext()->colorMask(red, green, blue, alpha);
 }
 
 void WebGLRenderingContextBase::compileShader(WebGLShader* shader)
 {
     if (isContextLost() || !validateWebGLObject("compileShader", shader))
@@ skipping 909 matching lines @@
         return ScriptValue::createNull(scriptState);
     const int intZero = 0;
     switch (pname) {
     case GL_ACTIVE_TEXTURE:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_ALIASED_LINE_WIDTH_RANGE:
         return getWebGLFloatArrayParameter(scriptState, pname);
     case GL_ALIASED_POINT_SIZE_RANGE:
         return getWebGLFloatArrayParameter(scriptState, pname);
     case GL_ALPHA_BITS:
-        return getIntParameter(scriptState, pname);
+        // Report 0 bits, if requested alpha attribute is false & drawingbuffer allocated as GL_RGBA
+        return (!m_requestedAttributes.alpha() && !drawingBuffer()->isRGBTextureSupported())
+            ? WebGLAny(scriptState, intZero)
+            : getIntParameter(scriptState, pname);
     case GL_ARRAY_BUFFER_BINDING:
         return WebGLAny(scriptState, PassRefPtrWillBeRawPtr<WebGLObject>(m_boundArrayBuffer.get()));
     case GL_BLEND:
         return getBooleanParameter(scriptState, pname);
     case GL_BLEND_COLOR:
         return getWebGLFloatArrayParameter(scriptState, pname);
     case GL_BLEND_DST_ALPHA:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLEND_DST_RGB:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLEND_EQUATION_ALPHA:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLEND_EQUATION_RGB:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLEND_SRC_ALPHA:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLEND_SRC_RGB:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_BLUE_BITS:
         return getIntParameter(scriptState, pname);
     case GL_COLOR_CLEAR_VALUE:
         return getWebGLFloatArrayParameter(scriptState, pname);
     case GL_COLOR_WRITEMASK:
-        return getBooleanArrayParameter(scriptState, pname);
+        return (!m_requestedAttributes.alpha() && !drawingBuffer()->isRGBTextureSupported())
+            ? WebGLAny(scriptState, intZero)
+            : getBooleanArrayParameter(scriptState, pname);
     case GL_COMPRESSED_TEXTURE_FORMATS:
         return WebGLAny(scriptState, DOMUint32Array::create(m_compressedTextureFormats.data(), m_compressedTextureFormats.size()));
     case GL_CULL_FACE:
         return getBooleanParameter(scriptState, pname);
     case GL_CULL_FACE_MODE:
         return getUnsignedIntParameter(scriptState, pname);
     case GL_CURRENT_PROGRAM:
         return WebGLAny(scriptState, PassRefPtrWillBeRawPtr<WebGLObject>(m_currentProgram.get()));
     case GL_DEPTH_BITS:
         if (!m_framebufferBinding && !m_requestedAttributes.depth())
@@ skipping 3802 matching lines @@
     return m_sharedWebGraphicsContext3D ? m_sharedWebGraphicsContext3D->drawingBuffer() : 0;
 }
 #else
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 #endif
 
 } // namespace blink