view src/video/SDL_pixels.c @ 3474:1edb86163d62

Of COURSE that trick wouldn't work on all renderers. Fall back to something for now, hopefully figure out a better way to do this later. If we have to, we can use vertical line and horizontal line textures for vertical and horizontal lines, and then create custom textures for diagonal lines and software render those. It's terrible, but at least it would be pixel perfect.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Nov 2009 07:22:59 +0000
parents 2b95b2c0b6d4
children fed6d4c6c693
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* General (mostly internal) pixel/color manipulation routines for SDL */

#include "SDL_endian.h"
#include "SDL_video.h"
#include "SDL_sysvideo.h"
#include "SDL_blit.h"
#include "SDL_pixels_c.h"
#include "SDL_RLEaccel_c.h"

/* Helper functions */

SDL_bool
SDL_PixelFormatEnumToMasks(Uint32 format, int *bpp, Uint32 * Rmask,
                           Uint32 * Gmask, Uint32 * Bmask, Uint32 * Amask)
{
    Uint32 masks[4];

    /* Initialize the values here */
    if (SDL_BYTESPERPIXEL(format) <= 2) {
        *bpp = SDL_BITSPERPIXEL(format);
    } else {
        *bpp = SDL_BYTESPERPIXEL(format) * 8;
    }
    *Rmask = *Gmask = *Bmask = *Amask = 0;

    if (SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED8 &&
        SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED16 &&
        SDL_PIXELTYPE(format) != SDL_PIXELTYPE_PACKED32) {
        /* Not a format that uses masks */
        return SDL_TRUE;
    }

    switch (SDL_PIXELLAYOUT(format)) {
    case SDL_PACKEDLAYOUT_332:
        masks[0] = 0x00000000;
        masks[1] = 0x000000E0;
        masks[2] = 0x0000001C;
        masks[3] = 0x00000003;
        break;
    case SDL_PACKEDLAYOUT_4444:
        masks[0] = 0x0000F000;
        masks[1] = 0x00000F00;
        masks[2] = 0x000000F0;
        masks[3] = 0x0000000F;
        break;
    case SDL_PACKEDLAYOUT_1555:
        masks[0] = 0x00008000;
        masks[1] = 0x00007C00;
        masks[2] = 0x000003E0;
        masks[3] = 0x0000001F;
        break;
    case SDL_PACKEDLAYOUT_5551:
        masks[0] = 0x0000F800;
        masks[1] = 0x000007C0;
        masks[2] = 0x0000003E;
        masks[3] = 0x00000001;
        break;
    case SDL_PACKEDLAYOUT_565:
        masks[0] = 0x00000000;
        masks[1] = 0x0000F800;
        masks[2] = 0x000007E0;
        masks[3] = 0x0000001F;
        break;
    case SDL_PACKEDLAYOUT_8888:
        masks[0] = 0xFF000000;
        masks[1] = 0x00FF0000;
        masks[2] = 0x0000FF00;
        masks[3] = 0x000000FF;
        break;
    case SDL_PACKEDLAYOUT_2101010:
        masks[0] = 0xC0000000;
        masks[1] = 0x3FF00000;
        masks[2] = 0x000FFC00;
        masks[3] = 0x000003FF;
        break;
    case SDL_PACKEDLAYOUT_1010102:
        masks[0] = 0xFFC00000;
        masks[1] = 0x003FF000;
        masks[2] = 0x00000FFC;
        masks[3] = 0x00000003;
        break;
    default:
        /* Unknown layout */
        return SDL_FALSE;
    }

    switch (SDL_PIXELORDER(format)) {
    case SDL_PACKEDORDER_XRGB:
        *Rmask = masks[1];
        *Gmask = masks[2];
        *Bmask = masks[3];
        break;
    case SDL_PACKEDORDER_RGBX:
        *Rmask = masks[0];
        *Gmask = masks[1];
        *Bmask = masks[2];
        break;
    case SDL_PACKEDORDER_ARGB:
        *Amask = masks[0];
        *Rmask = masks[1];
        *Gmask = masks[2];
        *Bmask = masks[3];
        break;
    case SDL_PACKEDORDER_RGBA:
        *Rmask = masks[0];
        *Gmask = masks[1];
        *Bmask = masks[2];
        *Amask = masks[3];
        break;
    case SDL_PACKEDORDER_XBGR:
        *Bmask = masks[1];
        *Gmask = masks[2];
        *Rmask = masks[3];
        break;
    case SDL_PACKEDORDER_BGRX:
        *Bmask = masks[0];
        *Gmask = masks[1];
        *Rmask = masks[2];
        break;
    case SDL_PACKEDORDER_BGRA:
        *Bmask = masks[0];
        *Gmask = masks[1];
        *Rmask = masks[2];
        *Amask = masks[3];
        break;
    case SDL_PACKEDORDER_ABGR:
        *Amask = masks[0];
        *Bmask = masks[1];
        *Gmask = masks[2];
        *Rmask = masks[3];
        break;
    default:
        /* Unknown order */
        return SDL_FALSE;
    }
    return SDL_TRUE;
}

Uint32
SDL_MasksToPixelFormatEnum(int bpp, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,
                           Uint32 Amask)
{
    switch (bpp) {
    case 8:
        switch (Rmask) {
        case 0:
            return SDL_PIXELFORMAT_INDEX8;
        case 0xE0:
            return SDL_PIXELFORMAT_RGB332;
        }
        break;
    case 12:
        switch (Rmask) {
        case 0x0F00:
            return SDL_PIXELFORMAT_RGB444;
        }
        break;
    case 15:
        switch (Rmask) {
        case 0x001F:
            return SDL_PIXELFORMAT_BGR555;
        case 0x7C00:
            return SDL_PIXELFORMAT_RGB555;
        }
        break;
    case 16:
        switch (Rmask) {
        case 0x000F:
            return SDL_PIXELFORMAT_ABGR4444;
        case 0x001F:
            if (Gmask == 0x07E0) {
                return SDL_PIXELFORMAT_BGR565;
            }
            return SDL_PIXELFORMAT_ABGR1555;
        case 0x0F00:
            return SDL_PIXELFORMAT_ARGB4444;
        case 0x7C00:
            return SDL_PIXELFORMAT_ARGB1555;
        case 0xF800:
            return SDL_PIXELFORMAT_RGB565;
        }
        break;
    case 24:
        switch (Rmask) {
        case 0x00FF0000:
            return SDL_PIXELFORMAT_RGB888;
        case 0x000000FF:
            return SDL_PIXELFORMAT_BGR888;
        case 0x00000000:
            /* FIXME: At this point we can't distinguish */
            /* if this format is RGB24 or BGR24          */
            return SDL_PIXELFORMAT_RGB24;
        }
    case 32:
        switch (Rmask) {
        case 0xFF000000:
            if (Amask == 0x000000FF) {
                return SDL_PIXELFORMAT_RGBA8888;
            }
            break;
        case 0x00FF0000:
            if (Amask == 0xFF000000) {
                return SDL_PIXELFORMAT_ARGB8888;
            } else {
                return SDL_PIXELFORMAT_RGB888;
            }
            break;
        case 0x0000FF00:
            if (Amask == 0x000000FF) {
                return SDL_PIXELFORMAT_BGRA8888;
            }
            break;
        case 0x000000FF:
            if (Amask == 0xFF000000) {
                return SDL_PIXELFORMAT_ABGR8888;
            } else {
                return SDL_PIXELFORMAT_BGR888;
            }
            break;
        case 0x3FF00000:
            return SDL_PIXELFORMAT_ARGB2101010;
        }
    }
    return SDL_PIXELFORMAT_UNKNOWN;
}


SDL_Palette *
SDL_AllocPalette(int ncolors)
{
    SDL_Palette *palette;

    palette = (SDL_Palette *) SDL_malloc(sizeof(*palette));
    if (!palette) {
        SDL_OutOfMemory();
        return NULL;
    }
    palette->colors =
        (SDL_Color *) SDL_malloc(ncolors * sizeof(*palette->colors));
    if (!palette->colors) {
        SDL_free(palette);
        return NULL;
    }
    palette->ncolors = ncolors;
    palette->watch = NULL;
    palette->refcount = 1;

    SDL_memset(palette->colors, 0xFF, ncolors * sizeof(*palette->colors));

    return palette;
}

int
SDL_AddPaletteWatch(SDL_Palette * palette, SDL_PaletteChangedFunc callback,
                    void *userdata)
{
    SDL_PaletteWatch *watch;

    if (!palette) {
        return -1;
    }

    watch = (SDL_PaletteWatch *) SDL_malloc(sizeof(*watch));
    if (!watch) {
        SDL_OutOfMemory();
        return -1;
    }

    watch->callback = callback;
    watch->userdata = userdata;
    watch->next = palette->watch;
    palette->watch = watch;
    ++palette->refcount;
    return 0;
}

void
SDL_DelPaletteWatch(SDL_Palette * palette, SDL_PaletteChangedFunc callback,
                    void *userdata)
{
    SDL_PaletteWatch *prev, *watch;

    if (!palette) {
        return;
    }

    for (prev = NULL, watch = palette->watch; watch;
         prev = watch, watch = watch->next) {
        if (watch->callback == callback && watch->userdata == userdata) {
            if (prev) {
                prev->next = watch->next;
            } else {
                palette->watch = watch->next;
            }
            SDL_free(watch);
            SDL_FreePalette(palette);
            return;
        }
    }
}

int
SDL_SetPaletteColors(SDL_Palette * palette, const SDL_Color * colors,
                     int firstcolor, int ncolors)
{
    SDL_PaletteWatch *watch;
    int status = 0;

    /* Verify the parameters */
    if (!palette) {
        return -1;
    }
    if (ncolors > (palette->ncolors - firstcolor)) {
        ncolors = (palette->ncolors - firstcolor);
        status = -1;
    }

    if (colors != (palette->colors + firstcolor)) {
        SDL_memcpy(palette->colors + firstcolor, colors,
                   ncolors * sizeof(*colors));
    }

    for (watch = palette->watch; watch; watch = watch->next) {
        if (watch->callback(watch->userdata, palette) < 0) {
            status = -1;
        }
    }

    return status;
}

void
SDL_FreePalette(SDL_Palette * palette)
{
    if (!palette) {
        return;
    }
    if (--palette->refcount > 0) {
        return;
    }
    if (palette->colors) {
        SDL_free(palette->colors);
    }
    SDL_free(palette);
}

/*
 * Allocate a pixel format structure and fill it according to the given info.
 */
SDL_PixelFormat *
SDL_AllocFormat(int bpp,
                Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
    SDL_PixelFormat *format;

    /* Allocate an empty pixel format structure */
    format = SDL_malloc(sizeof(*format));
    if (format == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }

    /* Set up the format */
    return SDL_InitFormat(format, bpp, Rmask, Gmask, Bmask, Amask);
}

SDL_PixelFormat *
SDL_InitFormat(SDL_PixelFormat * format, int bpp, Uint32 Rmask, Uint32 Gmask,
               Uint32 Bmask, Uint32 Amask)
{
    Uint32 mask;

    /* Set up the format */
    SDL_zerop(format);
    format->BitsPerPixel = bpp;
    format->BytesPerPixel = (bpp + 7) / 8;
    if (Rmask || Bmask || Gmask) {      /* Packed pixels with custom mask */
        format->Rshift = 0;
        format->Rloss = 8;
        if (Rmask) {
            for (mask = Rmask; !(mask & 0x01); mask >>= 1)
                ++format->Rshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Rloss;
        }
        format->Gshift = 0;
        format->Gloss = 8;
        if (Gmask) {
            for (mask = Gmask; !(mask & 0x01); mask >>= 1)
                ++format->Gshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Gloss;
        }
        format->Bshift = 0;
        format->Bloss = 8;
        if (Bmask) {
            for (mask = Bmask; !(mask & 0x01); mask >>= 1)
                ++format->Bshift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Bloss;
        }
        format->Ashift = 0;
        format->Aloss = 8;
        if (Amask) {
            for (mask = Amask; !(mask & 0x01); mask >>= 1)
                ++format->Ashift;
            for (; (mask & 0x01); mask >>= 1)
                --format->Aloss;
        }
        format->Rmask = Rmask;
        format->Gmask = Gmask;
        format->Bmask = Bmask;
        format->Amask = Amask;
    } else if (bpp > 8) {       /* Packed pixels with standard mask */
        /* R-G-B */
        if (bpp > 24)
            bpp = 24;
        format->Rloss = 8 - (bpp / 3);
        format->Gloss = 8 - (bpp / 3) - (bpp % 3);
        format->Bloss = 8 - (bpp / 3);
        format->Rshift = ((bpp / 3) + (bpp % 3)) + (bpp / 3);
        format->Gshift = (bpp / 3);
        format->Bshift = 0;
        format->Rmask = ((0xFF >> format->Rloss) << format->Rshift);
        format->Gmask = ((0xFF >> format->Gloss) << format->Gshift);
        format->Bmask = ((0xFF >> format->Bloss) << format->Bshift);
    } else {
        /* Palettized formats have no mask info */
        format->Rloss = 8;
        format->Gloss = 8;
        format->Bloss = 8;
        format->Aloss = 8;
        format->Rshift = 0;
        format->Gshift = 0;
        format->Bshift = 0;
        format->Ashift = 0;
        format->Rmask = 0;
        format->Gmask = 0;
        format->Bmask = 0;
        format->Amask = 0;
    }
    format->palette = NULL;

    return format;
}

/*
 * Change any previous mappings from/to the new surface format
 */
void
SDL_FormatChanged(SDL_Surface * surface)
{
    static int format_version = 0;
    ++format_version;
    if (format_version < 0) {   /* It wrapped... */
        format_version = 1;
    }
    surface->format_version = format_version;
    SDL_InvalidateMap(surface->map);
}

/*
 * Free a previously allocated format structure
 */
void
SDL_FreeFormat(SDL_PixelFormat * format)
{
    if (!format) {
        return;
    }
    SDL_free(format);
}

/*
 * Calculate an 8-bit (3 red, 3 green, 2 blue) dithered palette of colors
 */
void
SDL_DitherColors(SDL_Color * colors, int bpp)
{
    int i;
    if (bpp != 8)
        return;                 /* only 8bpp supported right now */

    for (i = 0; i < 256; i++) {
        int r, g, b;
        /* map each bit field to the full [0, 255] interval,
           so 0 is mapped to (0, 0, 0) and 255 to (255, 255, 255) */
        r = i & 0xe0;
        r |= r >> 3 | r >> 6;
        colors[i].r = r;
        g = (i << 3) & 0xe0;
        g |= g >> 3 | g >> 6;
        colors[i].g = g;
        b = i & 0x3;
        b |= b << 2;
        b |= b << 4;
        colors[i].b = b;
        colors[i].unused = SDL_ALPHA_OPAQUE;
    }
}

/* 
 * Calculate the pad-aligned scanline width of a surface
 */
int
SDL_CalculatePitch(SDL_Surface * surface)
{
    int pitch;

    /* Surface should be 4-byte aligned for speed */
    pitch = surface->w * surface->format->BytesPerPixel;
    switch (surface->format->BitsPerPixel) {
    case 1:
        pitch = (pitch + 7) / 8;
        break;
    case 4:
        pitch = (pitch + 1) / 2;
        break;
    default:
        break;
    }
    pitch = (pitch + 3) & ~3;   /* 4-byte aligning */
    return (pitch);
}

/*
 * Match an RGB value to a particular palette index
 */
Uint8
SDL_FindColor(SDL_Palette * pal, Uint8 r, Uint8 g, Uint8 b)
{
    /* Do colorspace distance matching */
    unsigned int smallest;
    unsigned int distance;
    int rd, gd, bd;
    int i;
    Uint8 pixel = 0;

    smallest = ~0;
    for (i = 0; i < pal->ncolors; ++i) {
        rd = pal->colors[i].r - r;
        gd = pal->colors[i].g - g;
        bd = pal->colors[i].b - b;
        distance = (rd * rd) + (gd * gd) + (bd * bd);
        if (distance < smallest) {
            pixel = i;
            if (distance == 0) {        /* Perfect match! */
                break;
            }
            smallest = distance;
        }
    }
    return (pixel);
}

/* Find the opaque pixel value corresponding to an RGB triple */
Uint32
SDL_MapRGB(const SDL_PixelFormat * format, Uint8 r, Uint8 g, Uint8 b)
{
    if (format->palette == NULL) {
        return (r >> format->Rloss) << format->Rshift
            | (g >> format->Gloss) << format->Gshift
            | (b >> format->Bloss) << format->Bshift | format->Amask;
    } else {
        return SDL_FindColor(format->palette, r, g, b);
    }
}

/* Find the pixel value corresponding to an RGBA quadruple */
Uint32
SDL_MapRGBA(const SDL_PixelFormat * format, Uint8 r, Uint8 g, Uint8 b,
            Uint8 a)
{
    if (format->palette == NULL) {
        return (r >> format->Rloss) << format->Rshift
            | (g >> format->Gloss) << format->Gshift
            | (b >> format->Bloss) << format->Bshift
            | ((a >> format->Aloss) << format->Ashift & format->Amask);
    } else {
        return SDL_FindColor(format->palette, r, g, b);
    }
}

void
SDL_GetRGB(Uint32 pixel, const SDL_PixelFormat * format, Uint8 * r, Uint8 * g,
           Uint8 * b)
{
    if (format->palette == NULL) {
        /*
         * This makes sure that the result is mapped to the
         * interval [0..255], and the maximum value for each
         * component is 255. This is important to make sure
         * that white is indeed reported as (255, 255, 255).
         * This only works for RGB bit fields at least 4 bit
         * wide, which is almost always the case.
         */
        unsigned v;
        v = (pixel & format->Rmask) >> format->Rshift;
        *r = (v << format->Rloss) + (v >> (8 - (format->Rloss << 1)));
        v = (pixel & format->Gmask) >> format->Gshift;
        *g = (v << format->Gloss) + (v >> (8 - (format->Gloss << 1)));
        v = (pixel & format->Bmask) >> format->Bshift;
        *b = (v << format->Bloss) + (v >> (8 - (format->Bloss << 1)));
    } else {
        *r = format->palette->colors[pixel].r;
        *g = format->palette->colors[pixel].g;
        *b = format->palette->colors[pixel].b;
    }
}

void
SDL_GetRGBA(Uint32 pixel, const SDL_PixelFormat * format,
            Uint8 * r, Uint8 * g, Uint8 * b, Uint8 * a)
{
    if (format->palette == NULL) {
        /*
         * This makes sure that the result is mapped to the
         * interval [0..255], and the maximum value for each
         * component is 255. This is important to make sure
         * that white is indeed reported as (255, 255, 255),
         * and that opaque alpha is 255.
         * This only works for RGB bit fields at least 4 bit
         * wide, which is almost always the case.
         */
        unsigned v;
        v = (pixel & format->Rmask) >> format->Rshift;
        *r = (v << format->Rloss) + (v >> (8 - (format->Rloss << 1)));
        v = (pixel & format->Gmask) >> format->Gshift;
        *g = (v << format->Gloss) + (v >> (8 - (format->Gloss << 1)));
        v = (pixel & format->Bmask) >> format->Bshift;
        *b = (v << format->Bloss) + (v >> (8 - (format->Bloss << 1)));
        if (format->Amask) {
            v = (pixel & format->Amask) >> format->Ashift;
            *a = (v << format->Aloss) + (v >> (8 - (format->Aloss << 1)));
        } else {
            *a = SDL_ALPHA_OPAQUE;
        }
    } else {
        *r = format->palette->colors[pixel].r;
        *g = format->palette->colors[pixel].g;
        *b = format->palette->colors[pixel].b;
        *a = SDL_ALPHA_OPAQUE;
    }
}

/* Apply gamma to a set of colors - this is easy. :) */
void
SDL_ApplyGamma(Uint16 * gamma, SDL_Color * colors, SDL_Color * output,
               int ncolors)
{
    int i;

    for (i = 0; i < ncolors; ++i) {
        output[i].r = gamma[0 * 256 + colors[i].r] >> 8;
        output[i].g = gamma[1 * 256 + colors[i].g] >> 8;
        output[i].b = gamma[2 * 256 + colors[i].b] >> 8;
    }
}

/* Map from Palette to Palette */
static Uint8 *
Map1to1(SDL_Palette * src, SDL_Palette * dst, int *identical)
{
    Uint8 *map;
    int i;

    if (identical) {
        if (src->ncolors <= dst->ncolors) {
            /* If an identical palette, no need to map */
            if (src == dst
                ||
                (SDL_memcmp
                 (src->colors, dst->colors,
                  src->ncolors * sizeof(SDL_Color)) == 0)) {
                *identical = 1;
                return (NULL);
            }
        }
        *identical = 0;
    }
    map = (Uint8 *) SDL_malloc(src->ncolors);
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }
    for (i = 0; i < src->ncolors; ++i) {
        map[i] = SDL_FindColor(dst,
                               src->colors[i].r, src->colors[i].g,
                               src->colors[i].b);
    }
    return (map);
}

/* Map from Palette to BitField */
static Uint8 *
Map1toN(SDL_PixelFormat * src, Uint8 Rmod, Uint8 Gmod, Uint8 Bmod, Uint8 Amod,
        SDL_PixelFormat * dst)
{
    Uint8 *map;
    int i;
    int bpp;
    SDL_Palette *pal = src->palette;

    bpp = ((dst->BytesPerPixel == 3) ? 4 : dst->BytesPerPixel);
    map = (Uint8 *) SDL_malloc(pal->ncolors * bpp);
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }

    /* We memory copy to the pixel map so the endianness is preserved */
    for (i = 0; i < pal->ncolors; ++i) {
        Uint8 A = Amod;
        Uint8 R = (Uint8) ((pal->colors[i].r * Rmod) / 255);
        Uint8 G = (Uint8) ((pal->colors[i].g * Gmod) / 255);
        Uint8 B = (Uint8) ((pal->colors[i].b * Bmod) / 255);
        ASSEMBLE_RGBA(&map[i * bpp], dst->BytesPerPixel, dst, R, G, B, A);
    }
    return (map);
}

/* Map from BitField to Dithered-Palette to Palette */
static Uint8 *
MapNto1(SDL_PixelFormat * src, SDL_PixelFormat * dst, int *identical)
{
    /* Generate a 256 color dither palette */
    SDL_Palette dithered;
    SDL_Color colors[256];
    SDL_Palette *pal = dst->palette;

    dithered.ncolors = 256;
    SDL_DitherColors(colors, 8);
    dithered.colors = colors;
    return (Map1to1(&dithered, pal, identical));
}

SDL_BlitMap *
SDL_AllocBlitMap(void)
{
    SDL_BlitMap *map;

    /* Allocate the empty map */
    map = (SDL_BlitMap *) SDL_calloc(1, sizeof(*map));
    if (map == NULL) {
        SDL_OutOfMemory();
        return (NULL);
    }
    map->info.r = 0xFF;
    map->info.g = 0xFF;
    map->info.b = 0xFF;
    map->info.a = 0xFF;

    /* It's ready to go */
    return (map);
}

void
SDL_InvalidateMap(SDL_BlitMap * map)
{
    if (!map) {
        return;
    }
    map->dst = NULL;
    map->format_version = (unsigned int) -1;
    if (map->info.table) {
        SDL_free(map->info.table);
        map->info.table = NULL;
    }
}

int
SDL_MapSurface(SDL_Surface * src, SDL_Surface * dst)
{
    SDL_PixelFormat *srcfmt;
    SDL_PixelFormat *dstfmt;
    SDL_BlitMap *map;

    /* Clear out any previous mapping */
    map = src->map;
    if ((src->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {
        SDL_UnRLESurface(src, 1);
    }
    SDL_InvalidateMap(map);

    /* Figure out what kind of mapping we're doing */
    map->identity = 0;
    srcfmt = src->format;
    dstfmt = dst->format;
    switch (srcfmt->BytesPerPixel) {
    case 1:
        switch (dstfmt->BytesPerPixel) {
        case 1:
            /* Palette --> Palette */
            map->info.table =
                Map1to1(srcfmt->palette, dstfmt->palette, &map->identity);
            if (!map->identity) {
                if (map->info.table == NULL) {
                    return (-1);
                }
            }
            if (srcfmt->BitsPerPixel != dstfmt->BitsPerPixel)
                map->identity = 0;
            break;

        default:
            /* Palette --> BitField */
            map->info.table =
                Map1toN(srcfmt, src->map->info.r, src->map->info.g,
                        src->map->info.b, src->map->info.a, dstfmt);
            if (map->info.table == NULL) {
                return (-1);
            }
            break;
        }
        break;
    default:
        switch (dstfmt->BytesPerPixel) {
        case 1:
            /* BitField --> Palette */
            map->info.table = MapNto1(srcfmt, dstfmt, &map->identity);
            if (!map->identity) {
                if (map->info.table == NULL) {
                    return (-1);
                }
            }
            map->identity = 0;  /* Don't optimize to copy */
            break;
        default:
            /* BitField --> BitField */
            if (FORMAT_EQUAL(srcfmt, dstfmt))
                map->identity = 1;
            break;
        }
        break;
    }

    map->dst = dst;
    map->format_version = dst->format_version;

    /* Choose your blitters wisely */
    return (SDL_CalculateBlit(src));
}

void
SDL_FreeBlitMap(SDL_BlitMap * map)
{
    if (map) {
        SDL_InvalidateMap(map);
        SDL_free(map);
    }
}

/* vi: set ts=4 sw=4 expandtab: */