WebGL 2: add types into glReadPixels

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 3691 matching lines @@
         webContext()->getIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &implFormat);
         webContext()->getIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &implType);
         if (!implFormat || !implType || format != static_cast<GLenum>(implFormat) || type != static_cast<GLenum>(implType)) {
             synthesizeGLError(GL_INVALID_OPERATION, "readPixels", "invalid format/type combination");
             return false;
         }
     }
     return true;
 }
 
-void WebGLRenderingContextBase::readPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum format, GLenum type, DOMArrayBufferView* pixels)
+DOMArrayBufferView::ViewType WebGLRenderingContextBase::readPixelsExpectedArrayBufferViewType(GLenum type)
 {
-    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))
-        return;
-
     DOMArrayBufferView::ViewType expectedViewType;

[Zhenyao Mo, 2015/08/14 16:07:42]

nit: you don't need this expectedViewType.  You can just return in each case,
saving one extra copying (although that's trivia).

     switch (type) {
     case GL_UNSIGNED_BYTE:
         expectedViewType = DOMArrayBufferView::TypeUint8;
         break;
-    case GL_BYTE:
-        expectedViewType = DOMArrayBufferView::TypeInt8;
-        break;
     case GL_UNSIGNED_SHORT_5_6_5:
     case GL_UNSIGNED_SHORT_4_4_4_4:
     case GL_UNSIGNED_SHORT_5_5_5_1:
         expectedViewType = DOMArrayBufferView::TypeUint16;
         break;
     case GL_FLOAT:
         expectedViewType = DOMArrayBufferView::TypeFloat32;
         break;
-    case GL_HALF_FLOAT:
     case GL_HALF_FLOAT_OES:
         expectedViewType = DOMArrayBufferView::TypeUint16;
         break;
-    case GL_UNSIGNED_INT:
-    case GL_UNSIGNED_INT_2_10_10_10_REV:
-    case GL_UNSIGNED_INT_10F_11F_11F_REV:
-    case GL_UNSIGNED_INT_5_9_9_9_REV:
-        expectedViewType = DOMArrayBufferView::TypeUint32;
-        break;
-    case GL_INT:
-        expectedViewType = DOMArrayBufferView::TypeInt32;
-        break;
     default:
         ASSERT_NOT_REACHED();
         expectedViewType = DOMArrayBufferView::TypeUint8;
         break;
     }
+    return expectedViewType;
+}
+
+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))
+        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);
@@ skipping 2864 matching lines @@
 
     return totalBytesPerPixel;
 }
 
 DrawingBuffer* WebGLRenderingContextBase::drawingBuffer() const
 {
     return m_drawingBuffer.get();
 }
 
 } // namespace blink