Source/platform/image-encoders/skia/WEBPImageEncoder.cpp

/*
 * Copyright (c) 2011, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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#include "config.h"
#include "platform/image-encoders/skia/WEBPImageEncoder.h"

#include "platform/geometry/IntSize.h"
#include "platform/graphics/ImageBuffer.h"
#include "webp/encode.h"

typedef int (*WebPImporter)(WebPPicture* const, const uint8_t* const data, int rowStride);

namespace blink {

static int writeOutput(const uint8_t* data, size_t size, const WebPPicture* const picture)
{
    static_cast<Vector<unsigned char>*>(picture->custom_ptr)->append(data, size);
    return 1;
}

static bool rgbPictureImport(const unsigned char* pixels, WebPImporter importRGB, WebPPicture* picture)
{
    // Write the RGB pixels to an rgb data buffer, alpha premultiplied, then import the rgb data.

    size_t pixelCount = picture->height * picture->width;

    OwnPtr<unsigned char[]> rgb = adoptArrayPtr(new unsigned char[pixelCount * 3]);
    if (!rgb.get())
        return false;

    for (unsigned char* data = rgb.get(); pixelCount-- > 0; pixels += 4) {
        unsigned char alpha = pixels[3];
        if (alpha != 255) {
            *data++ = SkMulDiv255Round(pixels[0], alpha);
            *data++ = SkMulDiv255Round(pixels[1], alpha);
            *data++ = SkMulDiv255Round(pixels[2], alpha);
        } else {
            *data++ = pixels[0];
            *data++ = pixels[1];
            *data++ = pixels[2];
        }
    }

    return importRGB(picture, rgb.get(), picture->width * 3);
}

static bool encodePixels(IntSize imageSize, const unsigned char* pixels, int quality, Vector<unsigned char>* output)
{
    if (imageSize.width() <= 0 || imageSize.width() > WEBP_MAX_DIMENSION)
        return false;
    if (imageSize.height() <= 0 || imageSize.height() > WEBP_MAX_DIMENSION)
        return false;

    WebPConfig config;
    if (!WebPConfigInit(&config))
        return false;
    WebPPicture picture;
    if (!WebPPictureInit(&picture))
        return false;

    picture.width = imageSize.width();
    picture.height = imageSize.height();

    if (!rgbPictureImport(pixels, &WebPPictureImportRGB, &picture))
        return false;

    picture.custom_ptr = output;
    picture.writer = &writeOutput;
    config.quality = quality;
    config.method = 3;

    bool success = WebPEncode(&config, &picture);
    WebPPictureFree(&picture);
    return success;
}

bool WEBPImageEncoder::encode(const ImageDataBuffer& imageData, int quality, Vector<unsigned char>* output)
{
    if (!imageData.pixels())
        return false;

    return encodePixels(IntSize(imageData.width(), imageData.height()), imageData.pixels(), quality, output);
}

} // namespace blink