WebGL 2: add readPixels API to read pixels into pixel pack buffer

Source/modules/webgl/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 1564 matching lines @@
     case GL_DYNAMIC_DRAW:
         break;
     default:
         synthesizeGLError(GL_INVALID_ENUM, "bufferData", "invalid usage");
         return;
     }
 
     if (!validateValueFitNonNegInt32("bufferData", "size", size))
         return;
 
+    buffer->setSize(size);
+
     webContext()->bufferData(target, static_cast<GLsizeiptr>(size), data, usage);
 }
 
 void WebGLRenderingContextBase::bufferData(GLenum target, long long size, GLenum usage)
 {
     if (isContextLost())
         return;
     if (!size) {
         synthesizeGLError(GL_INVALID_VALUE, "bufferData", "size == 0");
         return;
@@ skipping 2076 matching lines @@
     case GL_FLOAT:
         return DOMArrayBufferView::TypeFloat32;
     case GL_HALF_FLOAT_OES:
         return DOMArrayBufferView::TypeUint16;
     default:
         ASSERT_NOT_REACHED();
         return DOMArrayBufferView::TypeUint8;
     }
 }
 
+bool WebGLRenderingContextBase::validateReadPixelsFuncParameters(GLsizei width, GLsizei height, GLenum format, GLenum type, long long bufferSize)
+{
+    if (!validateReadPixelsFormatAndType(format, type))
+        return false;
+    WebGLFramebuffer* readFramebufferBinding = nullptr;
+    GLenum readBufferInternalFormat = 0, readBufferType = 0;
+    if (!validateReadBufferAndGetInfo("readPixels", readFramebufferBinding, &readBufferInternalFormat, &readBufferType))
+        return false;
+    if (!validateReadPixelsFormatTypeCombination(format, type, readBufferInternalFormat, readBufferType))
+        return false;
+
+    // Calculate array size, taking into consideration of PACK_ALIGNMENT.
+    unsigned totalBytesRequired = 0;
+    unsigned padding = 0;
+    GLenum error = WebGLImageConversion::computeImageSizeInBytes(format, type, width, height, m_packAlignment, &totalBytesRequired, &padding);
+    if (error != GL_NO_ERROR) {
+        synthesizeGLError(error, "readPixels", "invalid dimensions");
+        return false;
+    }
+    if (bufferSize < static_cast<long long>(totalBytesRequired)) {
+        synthesizeGLError(GL_INVALID_OPERATION, "readPixels", "buffer is not large enough for dimensions");
+        return false;
+    }
+    return true;
+}
+
 void WebGLRenderingContextBase::readPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum format, GLenum type, DOMArrayBufferView* pixels)
 {
     if (isContextLost())
         return;
     // Due to WebGL's same-origin restrictions, it is not possible to
     // taint the origin using the WebGL API.
     ASSERT(canvas()->originClean());
     // Validate input parameters.
     if (!pixels) {
         synthesizeGLError(GL_INVALID_VALUE, "readPixels", "no destination ArrayBufferView");
         return;
     }
-    if (!validateReadPixelsFormatAndType(format, type))
-        return;
-    GLenum readBufferInternalFormat = 0, readBufferType = 0;
-    WebGLFramebuffer* readFramebufferBinding = nullptr;
-    if (!validateReadBufferAndGetInfo("readPixels", readFramebufferBinding, &readBufferInternalFormat, &readBufferType))
-        return;
-    if (!validateReadPixelsFormatTypeCombination(format, type, readBufferInternalFormat, readBufferType))
+
+    if (!validateReadPixelsFuncParameters(width, height, format, type, static_cast<long long>(pixels->byteLength())))
         return;
 
     DOMArrayBufferView::ViewType expectedViewType = readPixelsExpectedArrayBufferViewType(type);
     // Validate array type against pixel type.
     if (pixels->type() != expectedViewType) {
         synthesizeGLError(GL_INVALID_OPERATION, "readPixels", "ArrayBufferView was the wrong type for the pixel format");
         return;
     }
 
-    // Calculate array size, taking into consideration of PACK_ALIGNMENT.
-    unsigned totalBytesRequired = 0;
-    unsigned padding = 0;
-    GLenum error = WebGLImageConversion::computeImageSizeInBytes(format, type, width, height, m_packAlignment, &totalBytesRequired, &padding);
-    if (error != GL_NO_ERROR) {
-        synthesizeGLError(error, "readPixels", "invalid dimensions");
-        return;
-    }
-    if (pixels->byteLength() < totalBytesRequired) {
-        synthesizeGLError(GL_INVALID_OPERATION, "readPixels", "ArrayBufferView not large enough for dimensions");
-        return;
-    }
-
     clearIfComposited();
     void* data = pixels->baseAddress();
 
+    GLenum target = isWebGL2OrHigher() ? GL_READ_FRAMEBUFFER : GL_FRAMEBUFFER;
+    WebGLFramebuffer* readFramebufferBinding = getFramebufferBinding(target);
     {
         ScopedDrawingBufferBinder binder(drawingBuffer(), readFramebufferBinding);
         webContext()->readPixels(x, y, width, height, format, type, data);
     }
 }
 
 void WebGLRenderingContextBase::renderbufferStorageImpl(
     GLenum target, GLsizei samples, GLenum internalformat, GLsizei width, GLsizei height,
     const char* functionName)
 {
@@ skipping 2948 matching lines @@
 
     return totalBytesPerPixel;
 }
 
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 
 } // namespace blink