Determine WebGL back-buffer on Mali-400 GPU

Source/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 87 matching lines @@
             extensionsUtil->ensureExtensionEnabled("GL_EXT_multisampled_render_to_texture");
     }
     bool packedDepthStencilSupported = extensionsUtil->supportsExtension("GL_OES_packed_depth_stencil");
     if (packedDepthStencilSupported)
         extensionsUtil->ensureExtensionEnabled("GL_OES_packed_depth_stencil");
     bool discardFramebufferSupported = extensionsUtil->supportsExtension("GL_EXT_discard_framebuffer");
     if (discardFramebufferSupported)
         extensionsUtil->ensureExtensionEnabled("GL_EXT_discard_framebuffer");
 
     RefPtr<DrawingBuffer> drawingBuffer = adoptRef(new DrawingBuffer(context, extensionsUtil.release(), multisampleSupported, packedDepthStencilSupported, discardFramebufferSupported, preserve, requestedAttributes));
+    Platform::current()->getGPUBlackList(&drawingBuffer->m_gpuBlackList);
+    // determineRGBTextureSupport() if GL_RGB not supported
+    if (!drawingBuffer->gpuBlackList().IsRGBTextureSupported())
+        drawingBuffer->determineRGBTextureSupport();
+
     if (!drawingBuffer->initialize(size)) {
         drawingBuffer->beginDestruction();
         return PassRefPtr<DrawingBuffer>();
     }
     return drawingBuffer.release();
 }
 
 DrawingBuffer::DrawingBuffer(PassOwnPtr<WebGraphicsContext3D> context,
     PassOwnPtr<Extensions3DUtil> extensionsUtil,
     bool multisampleExtensionSupported,
@@ skipping 25 matching lines @@
     , m_multisampleMode(None)
     , m_internalColorFormat(0)
     , m_colorFormat(0)
     , m_internalRenderbufferFormat(0)
     , m_maxTextureSize(0)
     , m_sampleCount(0)
     , m_packAlignment(4)
     , m_destructionInProgress(false)
     , m_isHidden(false)
     , m_filterQuality(kLow_SkFilterQuality)
+    , m_RGBTextureSupported(true)
 {
     // Used by browser tests to detect the use of a DrawingBuffer.
     TRACE_EVENT_INSTANT0("test_gpu", "DrawingBufferCreation", TRACE_EVENT_SCOPE_GLOBAL);
 #ifndef NDEBUG
     drawingBufferCounter.increment();
 #endif
 }
 
 DrawingBuffer::~DrawingBuffer()
 {
@@ skipping 233 matching lines @@
     ASSERT_NOT_REACHED();
 }
 
 bool DrawingBuffer::initialize(const IntSize& size)
 {
     if (m_context->isContextLost()) {
         // Need to try to restore the context again later.
         return false;
     }
 
-    if (m_requestedAttributes.alpha) {
+    if (m_requestedAttributes.alpha || !isRGBTextureSupported()) {
         m_internalColorFormat = GL_RGBA;
         m_colorFormat = GL_RGBA;
         m_internalRenderbufferFormat = GL_RGBA8_OES;
     } else {
         m_internalColorFormat = GL_RGB;
         m_colorFormat = GL_RGB;
         m_internalRenderbufferFormat = GL_RGB8_OES;
     }
 
     m_context->getIntegerv(GL_MAX_TEXTURE_SIZE, &m_maxTextureSize);
@@ skipping 291 matching lines @@
 void DrawingBuffer::clearFramebuffers(GLbitfield clearMask)
 {
     // We will clear the multisample FBO, but we also need to clear the non-multisampled buffer.
     if (m_multisampleFBO) {
         m_context->bindFramebuffer(GL_FRAMEBUFFER, m_fbo);
         m_context->clear(GL_COLOR_BUFFER_BIT);
     }
 
     m_context->bindFramebuffer(GL_FRAMEBUFFER, m_multisampleFBO ? m_multisampleFBO : m_fbo);
     m_context->clear(clearMask);
+
+    if (!m_requestedAttributes.alpha && !isRGBTextureSupported())
+        m_context->colorMask(true, true, true, false);
 }
 
 void DrawingBuffer::setSize(const IntSize& size)
 {
     if (m_size == size)
         return;
 
     m_size = size;
 }
 
@@ skipping 252 matching lines @@
 
 void DrawingBuffer::deleteChromiumImageForTexture(TextureInfo* info)
 {
     if (info->imageId) {
         m_context->releaseTexImage2DCHROMIUM(GL_TEXTURE_2D, info->imageId);
         m_context->destroyImageCHROMIUM(info->imageId);
         info->imageId = 0;
     }
 }
 
+void DrawingBuffer::determineRGBTextureSupport()
+{
+    // One time validation is required for GL_RGB texture
+    // so that DrawingBuffer can choose format for the backbuffer correctly.
+    // DrawingBuffer tries to allocate GL_RGB texture in case of alpha attribute false
+    // and fails because GL_RGB not supported on specific GPU's (e.g Mali- 2/3/400 family).
+    Platform3DObject fbo = m_context->createFramebuffer();
+    m_context->bindFramebuffer(GL_FRAMEBUFFER, fbo);
+    unsigned offscreenRGBTexture = createColorTexture();
+    m_context->texImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1, 1, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
+    m_context->framebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, offscreenRGBTexture, 0);
+    m_RGBTextureSupported = m_context->checkFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE;
+
+    if (fbo) {
+        m_context->deleteFramebuffer(fbo);
+        m_context->bindFramebuffer(GL_FRAMEBUFFER, 0);
+    }
+
+    if (offscreenRGBTexture)
+        m_context->deleteTexture(offscreenRGBTexture);
+}
+
 } // namespace blink