canvas: make a temporary buffer when a context doesn't exist.

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 3585 matching lines @@
 void WebGLRenderingContextBase::texImage2D(GLenum target, GLint level, GLenum internalformat,
     GLenum format, GLenum type, HTMLCanvasElement* canvas, ExceptionState& exceptionState)
 {
     if (isContextLost() || !validateHTMLCanvasElement("texImage2D", canvas, exceptionState) || !validateTexFunc("texImage2D", NotTexSubImage2D, SourceHTMLCanvasElement, target, level, internalformat, canvas->width(), canvas->height(), 0, format, type, 0, 0))
         return;
 
     WebGLTexture* texture = validateTextureBinding("texImage2D", target, true);
 
     // If possible, copy from the canvas element directly to the texture
     // via the GPU, without a read-back to system memory.
-    if (GL_TEXTURE_2D == target && texture) {
+    if (canvas->renderingContext() && GL_TEXTURE_2D == target && texture) {
         ScopedTexture2DRestorer restorer(this);
 
         if (!canvas->is3D()) {
             ImageBuffer* buffer = canvas->buffer();

[dshwang, 2014/12/01 14:31:12]

Above change is needed because this line calls buffer().

             if (buffer && buffer->copyToPlatformTexture(webContext(), texture->object(), internalformat, type,
                 level, m_unpackPremultiplyAlpha, m_unpackFlipY)) {
                 texture->setLevelInfo(target, level, internalformat, canvas->width(), canvas->height(), type);
                 return;
             }
         } else {
             WebGLRenderingContextBase* gl = toWebGLRenderingContextBase(canvas->renderingContext());
             ScopedTexture2DRestorer restorer(gl);
-            if (gl && gl->drawingBuffer()->copyToPlatformTexture(webContext(), texture->object(), internalformat, type,
+            if (gl->drawingBuffer()->copyToPlatformTexture(webContext(), texture->object(), internalformat, type,
                 level, m_unpackPremultiplyAlpha, !m_unpackFlipY, BackBuffer)) {
                 texture->setLevelInfo(target, level, internalformat, canvas->width(), canvas->height(), type);
                 return;
             }
         }
     }
 
-    texImage2DImpl(target, level, internalformat, format, type, canvas->copiedImage(BackBuffer), WebGLImageConversion::HtmlDomCanvas, m_unpackFlipY, m_unpackPremultiplyAlpha, exceptionState);
+    texImage2DImpl(target, level, internalformat, format, type, canvas->copiedImage(BackBuffer).get(), WebGLImageConversion::HtmlDomCanvas, m_unpackFlipY, m_unpackPremultiplyAlpha, exceptionState);
 }
 
 PassRefPtr<Image> WebGLRenderingContextBase::videoFrameToImage(HTMLVideoElement* video, BackingStoreCopy backingStoreCopy)
 {
     IntSize size(video->videoWidth(), video->videoHeight());
     ImageBuffer* buf = m_generatedImageCache.imageBuffer(size);
     if (!buf) {
         synthesizeGLError(GL_OUT_OF_MEMORY, "texImage2D", "out of memory");
         return nullptr;
     }
@@ skipping 213 matching lines @@
     texSubImage2DImpl(target, level, xoffset, yoffset, format, type, imageForRender.get(), WebGLImageConversion::HtmlDomImage, m_unpackFlipY, m_unpackPremultiplyAlpha, exceptionState);
 }
 
 void WebGLRenderingContextBase::texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset,
     GLenum format, GLenum type, HTMLCanvasElement* canvas, ExceptionState& exceptionState)
 {
     if (isContextLost() || !validateHTMLCanvasElement("texSubImage2D", canvas, exceptionState)
         || !validateTexFunc("texSubImage2D", TexSubImage2D, SourceHTMLCanvasElement, target, level, format, canvas->width(), canvas->height(), 0, format, type, xoffset, yoffset))
         return;
 
-    texSubImage2DImpl(target, level, xoffset, yoffset, format, type, canvas->copiedImage(BackBuffer), WebGLImageConversion::HtmlDomCanvas, m_unpackFlipY, m_unpackPremultiplyAlpha, exceptionState);
+    texSubImage2DImpl(target, level, xoffset, yoffset, format, type, canvas->copiedImage(BackBuffer).get(), WebGLImageConversion::HtmlDomCanvas, m_unpackFlipY, m_unpackPremultiplyAlpha, exceptionState);
 }
 
 void WebGLRenderingContextBase::texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset,
     GLenum format, GLenum type, HTMLVideoElement* video, ExceptionState& exceptionState)
 {
     if (isContextLost() || !validateHTMLVideoElement("texSubImage2D", video, exceptionState)
         || !validateTexFunc("texSubImage2D", TexSubImage2D, SourceHTMLVideoElement, target, level, format, video->videoWidth(), video->videoHeight(), 0, format, type, xoffset, yoffset))
         return;
 
     RefPtr<Image> image = videoFrameToImage(video, ImageBuffer::fastCopyImageMode());
@@ skipping 1487 matching lines @@
 
     if (wouldTaintOrigin(image)) {
         exceptionState.throwSecurityError("The cross-origin image at " + url.elidedString() + " may not be loaded.");
         return false;
     }
     return true;
 }
 
 bool WebGLRenderingContextBase::validateHTMLCanvasElement(const char* functionName, HTMLCanvasElement* canvas, ExceptionState& exceptionState)
 {
-    if (!canvas || !canvas->buffer()) {
+    if (!canvas || !canvas->isDrawable()) {
         synthesizeGLError(GL_INVALID_VALUE, functionName, "no canvas");
         return false;
     }
     if (wouldTaintOrigin(canvas)) {
         exceptionState.throwSecurityError("Tainted canvases may not be loaded.");
         return false;
     }
     return true;
 }
 
@@ skipping 486 matching lines @@
     return m_sharedWebGraphicsContext3D ? m_sharedWebGraphicsContext3D->drawingBuffer() : 0;
 }
 #else
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 #endif
 
 } // namespace blink