imagebufferskia.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (c) 2008, Google Inc. All rights reserved.
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 * 
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 * 
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 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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#include "config.h"
#include "ImageBuffer.h"

#include "Base64.h"
#include "BitmapImage.h"
#include "BitmapImageSingleFrameSkia.h"
#include "GraphicsContext.h"
#include "ImageData.h"
#include "NotImplemented.h"
#include "PlatformContextSkia.h"
#include "PNGImageEncoder.h"
#include "SkiaUtils.h"

using namespace std;

namespace WebCore {

// We pass a technically-uninitialized canvas to the platform context here since
// the canvas initialization completes in ImageBuffer::ImageBuffer. But
// PlatformContext doesn't actually need to use the object, and this makes all
// the ownership easier to manage.
ImageBufferData::ImageBufferData(const IntSize& size)
    : m_platformContext(0)  // Canvas is set in ImageBuffer constructor.
{
}

ImageBuffer::ImageBuffer(const IntSize& size, bool grayScale, bool& success)
    : m_data(size)
    , m_size(size)
{
    if (!m_data.m_canvas.initialize(size.width(), size.height(), false)) {
        success = false;
        return;
    }

    m_data.m_platformContext.setCanvas(&m_data.m_canvas);
    m_context.set(new GraphicsContext(&m_data.m_platformContext));
#if PLATFORM(WIN_OS)
    m_context->platformContext()->setDrawingToImageBuffer(true);
#endif

    // Make the background transparent. It would be nice if this wasn't
    // required, but the canvas is currently filled with the magic transparency
    // color. Can we have another way to manage this?
    m_data.m_canvas.drawARGB(0, 0, 0, 0, SkPorterDuff::kClear_Mode);
    success = true;
}

ImageBuffer::~ImageBuffer()
{
}

GraphicsContext* ImageBuffer::context() const
{
    return m_context.get();
}

Image* ImageBuffer::image() const
{
    if (!m_image) {
        // This creates a COPY of the image and will cache that copy. This means
        // that if subsequent operations take place on the context, neither the
        // currently-returned image, nor the results of future image() calls,
        // will contain that operation.
        //
        // This seems silly, but is the way the CG port works: image() is
        // intended to be used only when rendering is "complete."
        m_image = BitmapImageSingleFrameSkia::create(
            *m_data.m_platformContext.bitmap());
    }
    return m_image.get();
}

PassRefPtr<ImageData> ImageBuffer::getImageData(const IntRect& rect) const
{
    ASSERT(context());

    RefPtr<ImageData> result = ImageData::create(rect.width(), rect.height());
    unsigned char* data = result->data()->data()->data();

    if (rect.x() < 0 || rect.y() < 0 ||
        (rect.x() + rect.width()) > m_size.width() ||
        (rect.y() + rect.height()) > m_size.height())
        memset(data, 0, result->data()->length());

    int originX = rect.x();
    int destX = 0;
    if (originX < 0) {
        destX = -originX;
        originX = 0;
    }
    int endX = rect.x() + rect.width();
    if (endX > m_size.width())
        endX = m_size.width();
    int numColumns = endX - originX;

    int originY = rect.y();
    int destY = 0;
    if (originY < 0) {
        destY = -originY;
        originY = 0;
    }
    int endY = rect.y() + rect.height();
    if (endY > m_size.height())
        endY = m_size.height();
    int numRows = endY - originY;

    const SkBitmap& bitmap = *context()->platformContext()->bitmap();
    ASSERT(bitmap.config() == SkBitmap::kARGB_8888_Config);
    SkAutoLockPixels bitmapLock(bitmap);

    unsigned destBytesPerRow = 4 * rect.width();
    unsigned char* destRow = data + destY * destBytesPerRow + destX * 4;

    for (int y = 0; y < numRows; ++y) {
        uint32_t* srcRow = bitmap.getAddr32(originX, originY + y);
        for (int x = 0; x < numColumns; ++x) {
            SkColor color = SkPMColorToColor(srcRow[x]);
            unsigned char* destPixel = &destRow[x * 4];
            destPixel[0] = SkColorGetR(color);
            destPixel[1] = SkColorGetG(color);
            destPixel[2] = SkColorGetB(color);
            destPixel[3] = SkColorGetA(color);
        }
        destRow += destBytesPerRow;
    }

    return result;
}

void ImageBuffer::putImageData(ImageData* source, const IntRect& sourceRect,
                               const IntPoint& destPoint)
{
    ASSERT(sourceRect.width() > 0);
    ASSERT(sourceRect.height() > 0);

    int originX = sourceRect.x();
    int destX = destPoint.x() + sourceRect.x();
    ASSERT(destX >= 0);
    ASSERT(destX < m_size.width());
    ASSERT(originX >= 0);
    ASSERT(originX < sourceRect.right());

    int endX = destPoint.x() + sourceRect.right();
    ASSERT(endX <= m_size.width());

    int numColumns = endX - destX;

    int originY = sourceRect.y();
    int destY = destPoint.y() + sourceRect.y();
    ASSERT(destY >= 0);
    ASSERT(destY < m_size.height());
    ASSERT(originY >= 0);
    ASSERT(originY < sourceRect.bottom());

    int endY = destPoint.y() + sourceRect.bottom();
    ASSERT(endY <= m_size.height());
    int numRows = endY - destY;

    const SkBitmap& bitmap = *context()->platformContext()->bitmap();
    ASSERT(bitmap.config() == SkBitmap::kARGB_8888_Config);
    SkAutoLockPixels bitmapLock(bitmap);

    unsigned srcBytesPerRow = 4 * source->width();

    const unsigned char* srcRow = source->data()->data()->data() + originY * srcBytesPerRow + originX * 4;

    for (int y = 0; y < numRows; ++y) {
        uint32_t* destRow = bitmap.getAddr32(destX, destY + y);
        for (int x = 0; x < numColumns; ++x) {
            const unsigned char* srcPixel = &srcRow[x * 4];
            destRow[x] = SkPreMultiplyARGB(srcPixel[3], srcPixel[0],
                                           srcPixel[1], srcPixel[2]);
        }
        srcRow += srcBytesPerRow;
    }
}

String ImageBuffer::toDataURL(const String&) const
{
    // Encode the image into a vector.
    Vector<unsigned char> pngEncodedData;
    PNGImageEncoder::encode(*context()->platformContext()->bitmap(), &pngEncodedData);

    // Convert it into base64.
    Vector<char> base64EncodedData;
    base64Encode(*reinterpret_cast<Vector<char>*>(&pngEncodedData), base64EncodedData);
    // Append with a \0 so that it's a valid string.
    base64EncodedData.append('\0');

    // And the resulting string.
    return String::format("data:image/png;base64,%s", base64EncodedData.data());
}

} // namespace WebCore