Source/WebCore/platform/graphics/opengl/GraphicsContextGLOpenGL.cpp

/*
 * Copyright (C) 2010, 2016 Apple Inc. All rights reserved.
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2010 Mozilla Corporation. 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
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "GraphicsContextGLOpenGL.h"

#if ENABLE(WEBGL)

#include "ExtensionsGL.h"
#include "ImageBuffer.h"
#include "PixelBuffer.h"
#include <memory>
#include <wtf/UniqueArray.h>

namespace WebCore {

void GraphicsContextGLOpenGL::paintRenderingResultsToCanvas(ImageBuffer& imageBuffer)
{
    if (!makeContextCurrent())
        return;
    if (getInternalFramebufferSize().isEmpty())
        return;
    auto pixelBuffer = readRenderingResults();
    if (!pixelBuffer)
        return;
    paintToCanvas(contextAttributes(), WTFMove(*pixelBuffer), imageBuffer.backendSize(), imageBuffer.context());
}

void GraphicsContextGLOpenGL::paintCompositedResultsToCanvas(ImageBuffer& imageBuffer)
{
    if (!makeContextCurrent())
        return;
    if (getInternalFramebufferSize().isEmpty())
        return;
    auto pixelBuffer = readCompositedResults();
    if (!pixelBuffer)
        return;
    paintToCanvas(contextAttributes(), WTFMove(*pixelBuffer), imageBuffer.backendSize(), imageBuffer.context());
}

std::optional<PixelBuffer> GraphicsContextGLOpenGL::paintRenderingResultsToPixelBuffer()
{
    // Reading premultiplied alpha would involve unpremultiplying, which is lossy.
    if (contextAttributes().premultipliedAlpha)
        return std::nullopt;
    auto results = readRenderingResultsForPainting();
    if (results && !results->size().isEmpty()) {
        ASSERT(results->format().pixelFormat == PixelFormat::RGBA8 || results->format().pixelFormat == PixelFormat::BGRA8);
        // FIXME: Make PixelBufferConversions support negative rowBytes and in-place conversions.
        const auto size = results->size();
        const size_t rowStride = size.width() * 4;
        uint8_t* top = results->data().data();
        uint8_t* bottom = top + (size.height() - 1) * rowStride;
        std::unique_ptr<uint8_t[]> temp(new uint8_t[rowStride]);
        for (; top < bottom; top += rowStride, bottom -= rowStride) {
            memcpy(temp.get(), bottom, rowStride);
            memcpy(bottom, top, rowStride);
            memcpy(top, temp.get(), rowStride);
        }
    }
    return results;
}

std::optional<PixelBuffer> GraphicsContextGLOpenGL::readRenderingResultsForPainting()
{
    if (!makeContextCurrent())
        return std::nullopt;
    if (getInternalFramebufferSize().isEmpty())
        return std::nullopt;
    return readRenderingResults();
}

std::optional<PixelBuffer> GraphicsContextGLOpenGL::readCompositedResultsForPainting()
{
    if (!makeContextCurrent())
        return std::nullopt;
    if (getInternalFramebufferSize().isEmpty())
        return std::nullopt;
    return readCompositedResults();
}

} // namespace WebCore

#endif // ENABLE(WEBGL)