Revert of webgl: use immutable texture for the default FBO.

third_party/WebKit/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 133 matching lines @@
     , m_drawFramebufferBinding(0)
     , m_readFramebufferBinding(0)
     , m_activeTextureUnit(GL_TEXTURE0)
     , m_context(context)
     , m_extensionsUtil(extensionsUtil)
     , m_size(-1, -1)
     , m_requestedAttributes(requestedAttributes)
     , m_multisampleExtensionSupported(multisampleExtensionSupported)
     , m_packedDepthStencilExtensionSupported(packedDepthStencilExtensionSupported)
     , m_discardFramebufferSupported(discardFramebufferSupported)
-    , m_storageTextureSupported(false)
     , m_fbo(0)
     , m_depthStencilBuffer(0)
     , m_depthBuffer(0)
     , m_stencilBuffer(0)
     , m_multisampleFBO(0)
     , m_multisampleColorBuffer(0)
     , m_contentsChanged(true)
     , m_contentsChangeCommitted(false)
     , m_bufferClearNeeded(false)
     , m_antiAliasingMode(None)
@@ skipping 134 matching lines @@
             m_context->framebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer.textureId, 0, m_sampleCount);
         else
             m_context->framebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer.textureId, 0);
 
         if (m_discardFramebufferSupported) {
             // Explicitly discard framebuffer to save GPU memory bandwidth for tile-based GPU arch.
             const WGC3Denum attachments[3] = { GL_COLOR_ATTACHMENT0, GL_DEPTH_ATTACHMENT, GL_STENCIL_ATTACHMENT};
             m_context->discardFramebufferEXT(GL_FRAMEBUFFER, 3, attachments);
         }
     } else {
-        m_context->copySubTextureCHROMIUM(GL_TEXTURE_2D, m_colorBuffer.textureId, frontColorBufferMailbox->textureInfo.textureId,
-            0, 0, 0, 0, m_size.width(), m_size.height(), GL_FALSE, GL_FALSE, GL_FALSE);
+        m_context->copyTextureCHROMIUM(GL_TEXTURE_2D, m_colorBuffer.textureId, frontColorBufferMailbox->textureInfo.textureId, GL_RGBA, GL_UNSIGNED_BYTE, GL_FALSE, GL_FALSE, GL_FALSE);
     }
 
     restoreFramebufferBindings();
     m_contentsChanged = false;
 
     m_context->produceTextureDirectCHROMIUM(frontColorBufferMailbox->textureInfo.textureId, GL_TEXTURE_2D, frontColorBufferMailbox->mailbox.name);
     m_context->flush();
     frontColorBufferMailbox->mailbox.validSyncToken = m_context->insertSyncPoint(frontColorBufferMailbox->mailbox.syncToken);
     frontColorBufferMailbox->mailbox.allowOverlay = frontColorBufferMailbox->textureInfo.imageId != 0;
     setBufferClearNeeded(true);
@@ skipping 123 matching lines @@
     if (m_requestedAttributes.antialias && m_multisampleExtensionSupported) {
         m_context->getIntegerv(GL_MAX_SAMPLES_ANGLE, &maxSampleCount);
         m_antiAliasingMode = MSAAExplicitResolve;
         if (m_extensionsUtil->supportsExtension("GL_EXT_multisampled_render_to_texture")) {
             m_antiAliasingMode = MSAAImplicitResolve;
         } else if (m_extensionsUtil->supportsExtension("GL_CHROMIUM_screen_space_antialiasing")) {
             m_antiAliasingMode = ScreenSpaceAntialiasing;
         }
     }
     m_sampleCount = std::min(4, maxSampleCount);
-    m_storageTextureSupported = m_extensionsUtil->supportsExtension("GL_EXT_texture_storage");
 
     m_fbo = m_context->createFramebuffer();
 
     m_context->bindFramebuffer(GL_FRAMEBUFFER, m_fbo);
     m_colorBuffer.textureId = createColorTexture();
     if (m_antiAliasingMode == MSAAImplicitResolve)
         m_context->framebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer.textureId, 0, m_sampleCount);
     else
         m_context->framebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_colorBuffer.textureId, 0);
     createSecondaryBuffers();
@@ skipping 490 matching lines @@
     unsigned count = height / 2;
     for (unsigned i = 0; i < count; i++) {
         uint8* rowA = framebuffer + i * rowBytes;
         uint8* rowB = framebuffer + (height - i - 1) * rowBytes;
         memcpy(scanline, rowB, rowBytes);
         memcpy(rowB, rowA, rowBytes);
         memcpy(rowA, scanline, rowBytes);
     }
 }
 
+void DrawingBuffer::texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint unpackAlignment)
+{
+    ASSERT(unpackAlignment == 1 || unpackAlignment == 2 || unpackAlignment == 4 || unpackAlignment == 8);
+    m_context->texImage2D(target, level, internalformat, width, height, border, format, type, 0);
+}
+
 void DrawingBuffer::allocateTextureMemory(TextureInfo* info, const IntSize& size)
 {
     if (RuntimeEnabledFeatures::webGLImageChromiumEnabled()) {
         deleteChromiumImageForTexture(info);
 
         info->imageId = m_context->createGpuMemoryBufferImageCHROMIUM(size.width(), size.height(), GL_RGBA, GC3D_SCANOUT_CHROMIUM);
         if (info->imageId) {
             m_context->bindTexImage2DCHROMIUM(GL_TEXTURE_2D, info->imageId);
             return;
         }
     }
 
-    if (m_storageTextureSupported) {
-        if (info->immutable) {
-            m_context->deleteTexture(info->textureId);
-            info->textureId = createColorTexture();
-        }
-
-        // TODO(dshwang): GL_BGRA8_EXT can be better in some platforms. crbug.com/557848
-        m_context->texStorage2DEXT(GL_TEXTURE_2D, 1, m_internalRenderbufferFormat, size.width(), size.height());
-        info->immutable = true;
-        return;
-    }
-    m_context->texImage2D(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE, 0);
+    texImage2DResourceSafe(GL_TEXTURE_2D, 0, m_internalColorFormat, size.width(), size.height(), 0, m_colorFormat, GL_UNSIGNED_BYTE);
 }
 
 void DrawingBuffer::deleteChromiumImageForTexture(TextureInfo* info)
 {
     if (info->imageId) {
         m_context->releaseTexImage2DCHROMIUM(GL_TEXTURE_2D, info->imageId);
         m_context->destroyImageCHROMIUM(info->imageId);
         info->imageId = 0;
     }
 }
 
 } // namespace blink