/* vim:set sw=4 sts=4 et cin: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <gdk-pixbuf/gdk-pixbuf.h>

#include "nsImageToPixbuf.h"

#include "imgIContainer.h"

#include "mozilla/gfx/2D.h"

#include "mozilla/RefPtr.h"

using mozilla::gfx::DataSourceSurface;

using mozilla::gfx::SurfaceFormat;

NS_IMPL_ISUPPORTS(nsImageToPixbuf, nsIImageToPixbuf)

inline unsigned char

unpremultiply (unsigned char color,

               unsigned char alpha)

{

    if (alpha == 0)

        return 0;

    // plus alpha/2 to round instead of truncate

    return (color * 255 + alpha / 2) / alpha;

}

NS_IMETHODIMP_(GdkPixbuf*)

nsImageToPixbuf::ConvertImageToPixbuf(imgIContainer* aImage)

{

    return ImageToPixbuf(aImage);

}

GdkPixbuf*

nsImageToPixbuf::ImageToPixbuf(imgIContainer* aImage)

{

    RefPtr<SourceSurface> surface =

      aImage->GetFrame(imgIContainer::FRAME_CURRENT,

                       imgIContainer::FLAG_SYNC_DECODE);

    // If the last call failed, it was probably because our call stack originates

    // in an imgINotificationObserver event, meaning that we're not allowed request

    // a sync decode. Presumably the originating event is something sensible like

    // OnStopFrame(), so we can just retry the call without a sync decode.

    if (!surface)

      surface = aImage->GetFrame(imgIContainer::FRAME_CURRENT,

                                 imgIContainer::FLAG_NONE);

    NS_ENSURE_TRUE(surface, nullptr);

    return SourceSurfaceToPixbuf(surface,

                                 surface->GetSize().width,

                                 surface->GetSize().height);

}

GdkPixbuf*

nsImageToPixbuf::SourceSurfaceToPixbuf(SourceSurface* aSurface,

                                       int32_t aWidth,

                                       int32_t aHeight)

{

    MOZ_ASSERT(aWidth <= aSurface->GetSize().width &&

               aHeight <= aSurface->GetSize().height,

               "Requested rect is bigger than the supplied surface");

    GdkPixbuf* pixbuf = gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8,

                                       aWidth, aHeight);

    if (!pixbuf)

        return nullptr;

    uint32_t destStride = gdk_pixbuf_get_rowstride (pixbuf);

    guchar* destPixels = gdk_pixbuf_get_pixels (pixbuf);

    RefPtr<DataSourceSurface> dataSurface = aSurface->GetDataSurface();

    DataSourceSurface::MappedSurface map;

    if (!dataSurface->Map(DataSourceSurface::MapType::READ, &map))

        return nullptr;

    uint8_t* srcData = map.mData;

    int32_t srcStride = map.mStride;

    SurfaceFormat format = dataSurface->GetFormat();

    for (int32_t row = 0; row < aHeight; ++row) {

        for (int32_t col = 0; col < aWidth; ++col) {

            guchar* destPixel = destPixels + row * destStride + 4 * col;

            uint32_t* srcPixel =

                reinterpret_cast<uint32_t*>((srcData + row * srcStride + 4 * col));

            if (format == SurfaceFormat::B8G8R8A8) {

                const uint8_t a = (*srcPixel >> 24) & 0xFF;

                const uint8_t r = unpremultiply((*srcPixel >> 16) & 0xFF, a);

                const uint8_t g = unpremultiply((*srcPixel >>  8) & 0xFF, a);

                const uint8_t b = unpremultiply((*srcPixel >>  0) & 0xFF, a);

                *destPixel++ = r;

                *destPixel++ = g;

                *destPixel++ = b;

                *destPixel++ = a;

            } else {

                MOZ_ASSERT(format == SurfaceFormat::B8G8R8X8);

                const uint8_t r = (*srcPixel >> 16) & 0xFF;

                const uint8_t g = (*srcPixel >>  8) & 0xFF;

                const uint8_t b = (*srcPixel >>  0) & 0xFF;

                *destPixel++ = r;

                *destPixel++ = g;

                *destPixel++ = b;

                *destPixel++ = 0xFF; // A

            }

        }

    }

    dataSurface->Unmap();

    return pixbuf;

}