/* static */ bool
gfxAlphaRecovery::RecoverAlpha(gfxImageSurface* blackSurf,
                               const gfxImageSurface* whiteSurf)
{
    mozilla::gfx::IntSize size = blackSurf->GetSize();

    if (size != whiteSurf->GetSize() ||
        (blackSurf->Format() != mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32 &&
         blackSurf->Format() != mozilla::gfx::SurfaceFormat::X8R8G8B8_UINT32) ||
        (whiteSurf->Format() != mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32 &&
         whiteSurf->Format() != mozilla::gfx::SurfaceFormat::X8R8G8B8_UINT32))
        return false;

#ifdef MOZILLA_MAY_SUPPORT_SSE2
    if (mozilla::supports_sse2() &&
        RecoverAlphaSSE2(blackSurf, whiteSurf)) {
        return true;
    }
#endif

    blackSurf->Flush();
    whiteSurf->Flush();

    unsigned char* blackData = blackSurf->Data();
    unsigned char* whiteData = whiteSurf->Data();

    for (int32_t i = 0; i < size.height; ++i) {
        uint32_t* blackPixel = reinterpret_cast<uint32_t*>(blackData);
        const uint32_t* whitePixel = reinterpret_cast<uint32_t*>(whiteData);
        for (int32_t j = 0; j < size.width; ++j) {
            uint32_t recovered = RecoverPixel(blackPixel[j], whitePixel[j]);
            blackPixel[j] = recovered;
        }
        blackData += blackSurf->Stride();
        whiteData += whiteSurf->Stride();
    }

    blackSurf->MarkDirty();

    return true;
}
/* static */ PRBool
gfxAlphaRecovery::RecoverAlpha(gfxImageSurface* blackSurf,
                               const gfxImageSurface* whiteSurf,
                               Analysis* analysis)
{
    gfxIntSize size = blackSurf->GetSize();

    if (size != whiteSurf->GetSize() ||
        (blackSurf->Format() != gfxASurface::ImageFormatARGB32 &&
         blackSurf->Format() != gfxASurface::ImageFormatRGB24) ||
        (whiteSurf->Format() != gfxASurface::ImageFormatARGB32 &&
         whiteSurf->Format() != gfxASurface::ImageFormatRGB24))
        return PR_FALSE;

    if (!analysis && RecoverAlphaSSE2(blackSurf, whiteSurf)) {
        return PR_TRUE;
    }

    blackSurf->Flush();
    whiteSurf->Flush();

    unsigned char* blackData = blackSurf->Data();
    unsigned char* whiteData = whiteSurf->Data();

    /* Get the alpha value of 'first' */
    PRUint32 first;
    if (size.width == 0 || size.height == 0) {
        first = 0;
    } else {
        if (!blackData || !whiteData)
            return PR_FALSE;

        first = RecoverPixel(*reinterpret_cast<PRUint32*>(blackData),
                             *reinterpret_cast<PRUint32*>(whiteData));
    }

    PRUint32 deltas = 0;
    for (PRInt32 i = 0; i < size.height; ++i) {
        PRUint32* blackPixel = reinterpret_cast<PRUint32*>(blackData);
        const PRUint32* whitePixel = reinterpret_cast<PRUint32*>(whiteData);
        for (PRInt32 j = 0; j < size.width; ++j) {
            PRUint32 recovered = RecoverPixel(blackPixel[j], whitePixel[j]);
            blackPixel[j] = recovered;
            deltas |= (first ^ recovered);
        }
        blackData += blackSurf->Stride();
        whiteData += whiteSurf->Stride();
    }

    blackSurf->MarkDirty();
    
    if (analysis) {
        analysis->uniformAlpha = (deltas >> 24) == 0;
        analysis->uniformColor = PR_FALSE;
        if (analysis->uniformAlpha) {
            double d_first_alpha = first >> 24;
            analysis->alpha = d_first_alpha/255.0;
            /* we only set uniformColor when the alpha is already uniform.
               it's only useful in that case ... and if the alpha was nonuniform
               then computing whether the color is uniform would require unpremultiplying
               every pixel */
            analysis->uniformColor = deltas == 0;
            if (analysis->uniformColor) {
                if (d_first_alpha == 0.0) {
                    /* can't unpremultiply, this is OK */
                    analysis->r = analysis->g = analysis->b = 0.0;
                } else {
                    analysis->r = (first & 0xFF)/d_first_alpha;
                    analysis->g = ((first >> 8) & 0xFF)/d_first_alpha;
                    analysis->b = ((first >> 16) & 0xFF)/d_first_alpha;
                }
            }
        }
    }