fbcompose.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);

        p |= p << 4;
        *buffer++ = p << 24;
    }
}

static FASTCALL void
fbFetch_r1g2b1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);
        CARD32  r,g,b;

        r = ((p & 0x8) * 0xff) << 13;
        g = ((p & 0x6) * 0x55) << 7;
        b = ((p & 0x1) * 0xff);
        *buffer++ = 0xff000000|r|g|b;
    }
}

static FASTCALL void
fbFetch_b1g2r1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);
        CARD32  r,g,b;

        b = ((p & 0x8) * 0xff) >> 3;
        g = ((p & 0x6) * 0x55) << 7;
        r = ((p & 0x1) * 0xff) << 16;
        *buffer++ = 0xff000000|r|g|b;
    }
}

static FASTCALL void
fbFetch_a1r1g1b1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);
        CARD32  a,r,g,b;

        a = ((p & 0x8) * 0xff) << 21;
        r = ((p & 0x4) * 0xff) << 14;
        g = ((p & 0x2) * 0xff) << 7;
        b = ((p & 0x1) * 0xff);
        *buffer++ = a|r|g|b;
    }
}

static FASTCALL void
fbFetch_a1b1g1r1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);
        CARD32  a,r,g,b;

        a = ((p & 0x8) * 0xff) << 21;
        r = ((p & 0x4) * 0xff) >> 3;
        g = ((p & 0x2) * 0xff) << 7;
        b = ((p & 0x1) * 0xff) << 16;
        *buffer++ = a|r|g|b;
    }
}

static FASTCALL void
fbFetch_c4 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = Fetch4(bits, i + x);

        *buffer++ = indexed->rgba[p];
    }
}

static FASTCALL void
fbFetch_a1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = ((CARD32 *)bits)[(i + x) >> 5];
        CARD32  a;
#if BITMAP_BIT_ORDER == MSBFirst
        a = p >> (0x1f - ((i+x) & 0x1f));
#else
        a = p >> ((i+x) & 0x1f);
#endif
        a = a & 1;
        a |= a << 1;
        a |= a << 2;
        a |= a << 4;
        *buffer++ = a << 24;
    }
}

static FASTCALL void
fbFetch_g1 (const FbBits *bits, int x, int width, CARD32 *buffer, miIndexedPtr indexed)
{
    int i;
    for (i = 0; i < width; ++i) {
        CARD32  p = ((CARD32 *)bits)[(i+x) >> 5];
        CARD32 a;
#if BITMAP_BIT_ORDER == MSBFirst
        a = p >> (0x1f - ((i+x) & 0x1f));
#else
        a = p >> ((i+x) & 0x1f);
#endif
        a = a & 1;
        *buffer++ = indexed->rgba[a];
    }
}

static fetchProc fetchProcForPicture (PicturePtr pict)
{
    switch(pict->format_code) {
    case PICT_a8r8g8b8: return fbFetch_a8r8g8b8;
    case PICT_x8r8g8b8: return fbFetch_x8r8g8b8;
    case PICT_a8b8g8r8: return fbFetch_a8b8g8r8;
    case PICT_x8b8g8r8: return fbFetch_x8b8g8r8;

        /* 24bpp formats */
    case PICT_r8g8b8: return fbFetch_r8g8b8;
    case PICT_b8g8r8: return fbFetch_b8g8r8;

        /* 16bpp formats */
    case PICT_r5g6b5: return fbFetch_r5g6b5;
    case PICT_b5g6r5: return fbFetch_b5g6r5;

    case PICT_a1r5g5b5: return fbFetch_a1r5g5b5;
    case PICT_x1r5g5b5: return fbFetch_x1r5g5b5;
    case PICT_a1b5g5r5: return fbFetch_a1b5g5r5;
    case PICT_x1b5g5r5: return fbFetch_x1b5g5r5;
    case PICT_a4r4g4b4: return fbFetch_a4r4g4b4;
    case PICT_x4r4g4b4: return fbFetch_x4r4g4b4;
    case PICT_a4b4g4r4: return fbFetch_a4b4g4r4;
    case PICT_x4b4g4r4: return fbFetch_x4b4g4r4;

        /* 8bpp formats */
    case PICT_a8: return  fbFetch_a8;
    case PICT_r3g3b2: return fbFetch_r3g3b2;
    case PICT_b2g3r3: return fbFetch_b2g3r3;
    case PICT_a2r2g2b2: return fbFetch_a2r2g2b2;
    case PICT_a2b2g2r2: return fbFetch_a2b2g2r2;
    case PICT_c8: return  fbFetch_c8;
    case PICT_g8: return  fbFetch_c8;

        /* 4bpp formats */
    case PICT_a4: return  fbFetch_a4;
    case PICT_r1g2b1: return fbFetch_r1g2b1;
    case PICT_b1g2r1: return fbFetch_b1g2r1;
    case PICT_a1r1g1b1: return fbFetch_a1r1g1b1;
    case PICT_a1b1g1r1: return fbFetch_a1b1g1r1;
    case PICT_c4: return  fbFetch_c4;
    case PICT_g4: return  fbFetch_c4;

        /* 1bpp formats */
    case PICT_a1: return  fbFetch_a1;
    case PICT_g1: return  fbFetch_g1;
    default:
        return NULL;
    }
}

/*
 * Pixel wise fetching
 */

typedef FASTCALL CARD32 (*fetchPixelProc)(const FbBits *bits, int offset, miIndexedPtr indexed);

static FASTCALL CARD32
fbFetchPixel_a8r8g8b8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    return ((CARD32 *)bits)[offset];
}

static FASTCALL CARD32
fbFetchPixel_x8r8g8b8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    return ((CARD32 *)bits)[offset] | 0xff000000;
}

static FASTCALL CARD32
fbFetchPixel_a8b8g8r8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD32 *)bits)[offset];

    return ((pixel & 0xff000000) |
	    ((pixel >> 16) & 0xff) |
	    (pixel & 0x0000ff00) |
	    ((pixel & 0xff) << 16));
}

static FASTCALL CARD32
fbFetchPixel_x8b8g8r8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD32 *)bits)[offset];

    return ((0xff000000) |
	    ((pixel >> 16) & 0xff) |
	    (pixel & 0x0000ff00) |
	    ((pixel & 0xff) << 16));
}

static FASTCALL CARD32
fbFetchPixel_r8g8b8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD8   *pixel = ((CARD8 *) bits) + (offset*3);
#if IMAGE_BYTE_ORDER == MSBFirst
    return (0xff000000 |
	    (pixel[0] << 16) |
	    (pixel[1] << 8) |
	    (pixel[2]));
#else
    return (0xff000000 |
            (pixel[2] << 16) |
            (pixel[1] << 8) |
            (pixel[0]));
#endif
}

static FASTCALL CARD32
fbFetchPixel_b8g8r8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD8   *pixel = ((CARD8 *) bits) + (offset*3);
#if IMAGE_BYTE_ORDER == MSBFirst
    return (0xff000000 |
	    (pixel[2] << 16) |
	    (pixel[1] << 8) |
	    (pixel[0]));
#else
    return (0xff000000 |
	    (pixel[0] << 16) |
	    (pixel[1] << 8) |
	    (pixel[2]));
#endif
}

static FASTCALL CARD32
fbFetchPixel_r5g6b5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    r = ((pixel & 0xf800) | ((pixel & 0xe000) >> 5)) << 8;
    g = ((pixel & 0x07e0) | ((pixel & 0x0600) >> 6)) << 5;
    b = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) >> 2;
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_b5g6r5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    b = ((pixel & 0xf800) | ((pixel & 0xe000) >> 5)) >> 8;
    g = ((pixel & 0x07e0) | ((pixel & 0x0600) >> 6)) << 5;
    r = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) << 14;
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a1r5g5b5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  a,r,g,b;

    a = (CARD32) ((CARD8) (0 - ((pixel & 0x8000) >> 15))) << 24;
    r = ((pixel & 0x7c00) | ((pixel & 0x7000) >> 5)) << 9;
    g = ((pixel & 0x03e0) | ((pixel & 0x0380) >> 5)) << 6;
    b = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) >> 2;
    return (a | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_x1r5g5b5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    r = ((pixel & 0x7c00) | ((pixel & 0x7000) >> 5)) << 9;
    g = ((pixel & 0x03e0) | ((pixel & 0x0380) >> 5)) << 6;
    b = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) >> 2;
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a1b5g5r5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  a,r,g,b;

    a = (CARD32) ((CARD8) (0 - ((pixel & 0x8000) >> 15))) << 24;
    b = ((pixel & 0x7c00) | ((pixel & 0x7000) >> 5)) >> 7;
    g = ((pixel & 0x03e0) | ((pixel & 0x0380) >> 5)) << 6;
    r = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) << 14;
    return (a | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_x1b5g5r5 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    b = ((pixel & 0x7c00) | ((pixel & 0x7000) >> 5)) >> 7;
    g = ((pixel & 0x03e0) | ((pixel & 0x0380) >> 5)) << 6;
    r = ((pixel & 0x001c) | ((pixel & 0x001f) << 5)) << 14;
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a4r4g4b4 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  a,r,g,b;

    a = ((pixel & 0xf000) | ((pixel & 0xf000) >> 4)) << 16;
    r = ((pixel & 0x0f00) | ((pixel & 0x0f00) >> 4)) << 12;
    g = ((pixel & 0x00f0) | ((pixel & 0x00f0) >> 4)) << 8;
    b = ((pixel & 0x000f) | ((pixel & 0x000f) << 4));
    return (a | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_x4r4g4b4 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    r = ((pixel & 0x0f00) | ((pixel & 0x0f00) >> 4)) << 12;
    g = ((pixel & 0x00f0) | ((pixel & 0x00f0) >> 4)) << 8;
    b = ((pixel & 0x000f) | ((pixel & 0x000f) << 4));
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a4b4g4r4 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  a,r,g,b;

    a = ((pixel & 0xf000) | ((pixel & 0xf000) >> 4)) << 16;
    b = ((pixel & 0x0f00) | ((pixel & 0x0f00) >> 4)) << 12;
    g = ((pixel & 0x00f0) | ((pixel & 0x00f0) >> 4)) << 8;
    r = ((pixel & 0x000f) | ((pixel & 0x000f) << 4));
    return (a | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_x4b4g4r4 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = ((CARD16 *) bits)[offset];
    CARD32  r,g,b;

    b = ((pixel & 0x0f00) | ((pixel & 0x0f00) >> 4)) << 12;
    g = ((pixel & 0x00f0) | ((pixel & 0x00f0) >> 4)) << 8;
    r = ((pixel & 0x000f) | ((pixel & 0x000f) << 4));
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];

    return pixel << 24;
}

static FASTCALL CARD32
fbFetchPixel_r3g3b2 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];
    CARD32  r,g,b;

    r = ((pixel & 0xe0) | ((pixel & 0xe0) >> 3) | ((pixel & 0xc0) >> 6)) << 16;
    g = ((pixel & 0x1c) | ((pixel & 0x18) >> 3) | ((pixel & 0x1c) << 3)) << 8;
    b = (((pixel & 0x03)     ) |
	 ((pixel & 0x03) << 2) |
	 ((pixel & 0x03) << 4) |
	 ((pixel & 0x03) << 6));
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_b2g3r3 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];
    CARD32  r,g,b;

    b = (((pixel & 0xc0)     ) |
	 ((pixel & 0xc0) >> 2) |
	 ((pixel & 0xc0) >> 4) |
	 ((pixel & 0xc0) >> 6));
    g = ((pixel & 0x38) | ((pixel & 0x38) >> 3) | ((pixel & 0x30) << 2)) << 8;
    r = (((pixel & 0x07)     ) |
	 ((pixel & 0x07) << 3) |
	 ((pixel & 0x06) << 6)) << 16;
    return (0xff000000 | r | g | b);
}

static FASTCALL CARD32
fbFetchPixel_a2r2g2b2 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];
    CARD32   a,r,g,b;

    a = ((pixel & 0xc0) * 0x55) << 18;
    r = ((pixel & 0x30) * 0x55) << 12;
    g = ((pixel & 0x0c) * 0x55) << 6;
    b = ((pixel & 0x03) * 0x55);
    return a|r|g|b;
}

static FASTCALL CARD32
fbFetchPixel_a2b2g2r2 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];
    CARD32   a,r,g,b;

    a = ((pixel & 0xc0) * 0x55) << 18;
    b = ((pixel & 0x30) * 0x55) >> 6;
    g = ((pixel & 0x0c) * 0x55) << 6;
    r = ((pixel & 0x03) * 0x55) << 16;
    return a|r|g|b;
}

static FASTCALL CARD32
fbFetchPixel_c8 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32   pixel = ((CARD8 *) bits)[offset];
    return indexed->rgba[pixel];
}

#define Fetch8(l,o)    (((CARD8 *) (l))[(o) >> 2])
#if IMAGE_BYTE_ORDER == MSBFirst
#define Fetch4(l,o)    ((o) & 2 ? Fetch8(l,o) & 0xf : Fetch8(l,o) >> 4)
#else
#define Fetch4(l,o)    ((o) & 2 ? Fetch8(l,o) >> 4 : Fetch8(l,o) & 0xf)
#endif

static FASTCALL CARD32
fbFetchPixel_a4 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = Fetch4(bits, offset);

    pixel |= pixel << 4;
    return pixel << 24;
}

static FASTCALL CARD32
fbFetchPixel_r1g2b1 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = Fetch4(bits, offset);
    CARD32  r,g,b;

    r = ((pixel & 0x8) * 0xff) << 13;
    g = ((pixel & 0x6) * 0x55) << 7;
    b = ((pixel & 0x1) * 0xff);
    return 0xff000000|r|g|b;
}

static FASTCALL CARD32
fbFetchPixel_b1g2r1 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = Fetch4(bits, offset);
    CARD32  r,g,b;

    b = ((pixel & 0x8) * 0xff) >> 3;
    g = ((pixel & 0x6) * 0x55) << 7;
    r = ((pixel & 0x1) * 0xff) << 16;
    return 0xff000000|r|g|b;
}

static FASTCALL CARD32
fbFetchPixel_a1r1g1b1 (const FbBits *bits, int offset, miIndexedPtr indexed)
{
    CARD32  pixel = Fetch4(bits, offset);
    CARD32  a,r,g,b;

    a = ((pixel & 0x8) * 0xff) << 21;