mpv/libvo/osd_template.c

// Generic alpha renderers for all YUV modes and RGB depths.
// These are "reference implementations", should be optimized later (MMX, etc)

void vo_draw_alpha_yv12(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]) dstbase[x]=((dstbase[x]*srca[x])>>8)+src[x];
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}

void vo_draw_alpha_yuy2(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]) dstbase[2*x]=((dstbase[2*x]*srca[x])>>8)+src[x];
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}

void vo_draw_alpha_rgb24(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register unsigned char *dst = dstbase;
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]){
		dst[0]=((dst[0]*srca[x])>>8)+src[x];
		dst[1]=((dst[1]*srca[x])>>8)+src[x];
		dst[2]=((dst[2]*srca[x])>>8)+src[x];
            }
            dst+=3; // 24bpp
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}

void vo_draw_alpha_rgb32(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]){
		dstbase[4*x+0]=((dstbase[4*x+0]*srca[x])>>8)+src[x];
		dstbase[4*x+1]=((dstbase[4*x+1]*srca[x])>>8)+src[x];
		dstbase[4*x+2]=((dstbase[4*x+2]*srca[x])>>8)+src[x];
            }
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}

void vo_draw_alpha_rgb15(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register unsigned short *dst = (unsigned short*) dstbase;
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]){
                unsigned char r=dst[x]&0x1F;
                unsigned char g=(dst[x]>>5)&0x1F;
                unsigned char b=(dst[x]>>10)&0x1F;
                r=(((r*srca[x])>>5)+src[x])>>3;
                g=(((g*srca[x])>>5)+src[x])>>3;
                b=(((b*srca[x])>>5)+src[x])>>3;
                dst[x]=(b<<10)|(g<<5)|r;
            }
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}

void vo_draw_alpha_rgb16(int w,int h, unsigned char* src, unsigned char *srca, int srcstride, unsigned char* dstbase,int dststride){
    int y;
    for(y=0;y<h;y++){
        register unsigned short *dst = (unsigned short*) dstbase;
        register int x;
        for(x=0;x<w;x++){
            if(srca[x]){
                unsigned char r=dst[x]&0x1F;
                unsigned char g=(dst[x]>>5)&0x3F;
                unsigned char b=(dst[x]>>11)&0x1F;
                r=(((r*srca[x])>>5)+src[x])>>3;
                g=(((g*srca[x])>>6)+src[x])>>2;
                b=(((b*srca[x])>>5)+src[x])>>3;
                dst[x]=(b<<11)|(g<<5)|r;
            }
        }
        src+=srcstride;
        srca+=srcstride;
        dstbase+=dststride;
    }
    return;
}