view src/video/SDL_surface.c @ 3292:245a7d79577c

Fixed bug #615 Scott McCreary 2008-08-21 10:48:14 PDT This patch adds support for Haiku. http://ports.haiku-files.org/browser/haikuports/trunk/media-libs/libsdl/SDL-1.2.13-haiku.diff Haiku is an open-source recreation of BeOS. It has better POSIX compliance than beOS did, and other improved features, which in some cases causes us to have to "undo" previous BeOS workarounds. Here's our port log entry for it, showing the steps to force the changes into configure and Makefile: http://ports.haiku-files.org/wiki/media-libs/libsdl/1.2.13/1 Note that this was only tried on 1.2.13 stable so far. Haiku is using a newer config.guess / config.sub that doesn't yet seem to be in the released libtool, so we are having to copy it in for now. http://haiku-files.org/files/optional-packages/
author Sam Lantinga <slouken@libsdl.org>
date Mon, 21 Sep 2009 09:21:00 +0000
parents 7be21a78777e
children 147d6ef5be03
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"

#include "SDL_video.h"
#include "SDL_compat.h"
#include "SDL_sysvideo.h"
#include "SDL_blit.h"
#include "SDL_RLEaccel_c.h"
#include "SDL_pixels_c.h"
#include "SDL_leaks.h"


/* Public routines */
/*
 * Create an empty RGB surface of the appropriate depth
 */
SDL_Surface *
SDL_CreateRGBSurface(Uint32 flags,
                     int width, int height, int depth,
                     Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
{
    SDL_Surface *surface;

    /* The flags are no longer used, make the compiler happy */
    flags;

    /* Allocate the surface */
    surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface));
    if (surface == NULL) {
        SDL_OutOfMemory();
        return NULL;
    }

    surface->format = SDL_AllocFormat(depth, Rmask, Gmask, Bmask, Amask);
    if (!surface->format) {
        SDL_FreeSurface(surface);
        return NULL;
    }
    surface->w = width;
    surface->h = height;
    surface->pitch = SDL_CalculatePitch(surface);
    SDL_SetClipRect(surface, NULL);

    if (surface->format->BitsPerPixel <= 8) {
        SDL_Palette *palette =
            SDL_AllocPalette((1 << surface->format->BitsPerPixel));
        if (!palette) {
            SDL_FreeSurface(surface);
            return NULL;
        }
        if (Rmask || Bmask || Gmask) {
            const SDL_PixelFormat *format = surface->format;

            /* create palette according to masks */
            int i;
            int Rm = 0, Gm = 0, Bm = 0;
            int Rw = 0, Gw = 0, Bw = 0;

            if (Rmask) {
                Rw = 8 - format->Rloss;
                for (i = format->Rloss; i > 0; i -= Rw)
                    Rm |= 1 << i;
            }
            if (Gmask) {
                Gw = 8 - format->Gloss;
                for (i = format->Gloss; i > 0; i -= Gw)
                    Gm |= 1 << i;
            }
            if (Bmask) {
                Bw = 8 - format->Bloss;
                for (i = format->Bloss; i > 0; i -= Bw)
                    Bm |= 1 << i;
            }
            for (i = 0; i < palette->ncolors; ++i) {
                int r, g, b;
                r = (i & Rmask) >> format->Rshift;
                r = (r << format->Rloss) | ((r * Rm) >> Rw);
                palette->colors[i].r = r;

                g = (i & Gmask) >> format->Gshift;
                g = (g << format->Gloss) | ((g * Gm) >> Gw);
                palette->colors[i].g = g;

                b = (i & Bmask) >> format->Bshift;
                b = (b << format->Bloss) | ((b * Bm) >> Bw);
                palette->colors[i].b = b;
            }
        } else if (palette->ncolors == 2) {
            /* Create a black and white bitmap palette */
            palette->colors[0].r = 0xFF;
            palette->colors[0].g = 0xFF;
            palette->colors[0].b = 0xFF;
            palette->colors[1].r = 0x00;
            palette->colors[1].g = 0x00;
            palette->colors[1].b = 0x00;
        }
        SDL_SetSurfacePalette(surface, palette);
        SDL_FreePalette(palette);
    }

    /* Get the pixels */
    if (surface->w && surface->h) {
        surface->pixels = SDL_malloc(surface->h * surface->pitch);
        if (!surface->pixels) {
            SDL_FreeSurface(surface);
            SDL_OutOfMemory();
            return NULL;
        }
        /* This is important for bitmaps */
        SDL_memset(surface->pixels, 0, surface->h * surface->pitch);
    }

    /* Allocate an empty mapping */
    surface->map = SDL_AllocBlitMap();
    if (!surface->map) {
        SDL_FreeSurface(surface);
        return NULL;
    }
    SDL_FormatChanged(surface);

    /* By default surface with an alpha mask are set up for blending */
    if (Amask) {
        SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);
    }

    /* The surface is ready to go */
    surface->refcount = 1;
#ifdef CHECK_LEAKS
    ++surfaces_allocated;
#endif
    return surface;
}

/*
 * Create an RGB surface from an existing memory buffer
 */
SDL_Surface *
SDL_CreateRGBSurfaceFrom(void *pixels,
                         int width, int height, int depth, int pitch,
                         Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,
                         Uint32 Amask)
{
    SDL_Surface *surface;

    surface =
        SDL_CreateRGBSurface(0, 0, 0, depth, Rmask, Gmask, Bmask, Amask);
    if (surface != NULL) {
        surface->flags |= SDL_PREALLOC;
        surface->pixels = pixels;
        surface->w = width;
        surface->h = height;
        surface->pitch = pitch;
        SDL_SetClipRect(surface, NULL);
    }
    return surface;
}

static int
SDL_SurfacePaletteChanged(void *userdata, SDL_Palette * palette)
{
    SDL_Surface *surface = (SDL_Surface *) userdata;

    SDL_FormatChanged(surface);

    return 0;
}

int
SDL_SetSurfacePalette(SDL_Surface * surface, SDL_Palette * palette)
{
    if (!surface || !surface->format) {
        SDL_SetError("SDL_SetSurfacePalette() passed a NULL surface");
        return -1;
    }

    if (palette && palette->ncolors != (1 << surface->format->BitsPerPixel)) {
        SDL_SetError
            ("SDL_SetSurfacePalette() passed a palette that doesn't match the surface format");
        return -1;
    }

    if (surface->format->palette == palette) {
        return 0;
    }

    if (surface->format->palette) {
        SDL_DelPaletteWatch(surface->format->palette,
                            SDL_SurfacePaletteChanged, surface);
    }

    surface->format->palette = palette;

    if (surface->format->palette) {
        SDL_AddPaletteWatch(surface->format->palette,
                            SDL_SurfacePaletteChanged, surface);
    }
    return 0;
}

int
SDL_SetSurfaceRLE(SDL_Surface * surface, int flag)
{
    int flags;

    if (!surface) {
        return -1;
    }

    flags = surface->map->info.flags;
    if (flag) {
        surface->map->info.flags |= SDL_COPY_RLE_DESIRED;
    } else {
        surface->map->info.flags &= ~SDL_COPY_RLE_DESIRED;
    }
    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }
    return 0;
}

int
SDL_SetColorKey(SDL_Surface * surface, Uint32 flag, Uint32 key)
{
    int flags;

    if (!surface) {
        return -1;
    }

    if (flag & SDL_RLEACCEL) {
        SDL_SetSurfaceRLE(surface, 1);
    }

    flags = surface->map->info.flags;
    if (flag) {
        surface->map->info.flags |= SDL_COPY_COLORKEY;
        surface->map->info.colorkey = key;
    } else {
        surface->map->info.flags &= ~SDL_COPY_COLORKEY;
    }
    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }

    /* Compatibility mode */
    if (surface->map->info.flags & SDL_COPY_COLORKEY) {
        surface->flags |= SDL_SRCCOLORKEY;
    } else {
        surface->flags &= ~SDL_SRCCOLORKEY;
    }

    return 0;
}

int
SDL_GetColorKey(SDL_Surface * surface, Uint32 * key)
{
    if (!surface) {
        return -1;
    }

    if (!(surface->map->info.flags & SDL_COPY_COLORKEY)) {
        return -1;
    }

    if (key) {
        *key = surface->map->info.colorkey;
    }
    return 0;
}

/* This is a fairly slow function to switch from colorkey to alpha */
static void
SDL_ConvertColorkeyToAlpha(SDL_Surface * surface)
{
    int x, y;

    if (!surface) {
        return;
    }

    if (!(surface->map->info.flags & SDL_COPY_COLORKEY) ||
        !surface->format->Amask) {
        return;
    }

    SDL_LockSurface(surface);

    switch (surface->format->BytesPerPixel) {
    case 2:
        {
            Uint16 *row, *spot;
            Uint16 ckey = (Uint16) surface->map->info.colorkey;
            Uint16 mask = (Uint16) (~surface->format->Amask);

            row = (Uint16 *) surface->pixels;
            for (y = surface->h; y--;) {
                spot = row;
                for (x = surface->w; x--;) {
                    if (*spot == ckey) {
                        *spot &= mask;
                    }
                    ++spot;
                }
                row += surface->pitch / 2;
            }
        }
        break;
    case 3:
        /* FIXME */
        break;
    case 4:
        {
            Uint32 *row, *spot;
            Uint32 ckey = surface->map->info.colorkey;
            Uint32 mask = ~surface->format->Amask;

            row = (Uint32 *) surface->pixels;
            for (y = surface->h; y--;) {
                spot = row;
                for (x = surface->w; x--;) {
                    if (*spot == ckey) {
                        *spot &= mask;
                    }
                    ++spot;
                }
                row += surface->pitch / 4;
            }
        }
        break;
    }

    SDL_UnlockSurface(surface);

    SDL_SetColorKey(surface, 0, 0);
    SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);
}

int
SDL_SetSurfaceColorMod(SDL_Surface * surface, Uint8 r, Uint8 g, Uint8 b)
{
    int flags;

    if (!surface) {
        return -1;
    }

    surface->map->info.r = r;
    surface->map->info.g = g;
    surface->map->info.b = b;

    flags = surface->map->info.flags;
    if (r != 0xFF || g != 0xFF || b != 0xFF) {
        surface->map->info.flags |= SDL_COPY_MODULATE_COLOR;
    } else {
        surface->map->info.flags &= ~SDL_COPY_MODULATE_COLOR;
    }
    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }
    return 0;
}


int
SDL_GetSurfaceColorMod(SDL_Surface * surface, Uint8 * r, Uint8 * g, Uint8 * b)
{
    if (!surface) {
        return -1;
    }

    if (r) {
        *r = surface->map->info.r;
    }
    if (g) {
        *g = surface->map->info.g;
    }
    if (b) {
        *b = surface->map->info.b;
    }
    return 0;
}

int
SDL_SetSurfaceAlphaMod(SDL_Surface * surface, Uint8 alpha)
{
    int flags;

    if (!surface) {
        return -1;
    }

    surface->map->info.a = alpha;

    flags = surface->map->info.flags;
    if (alpha != 0xFF) {
        surface->map->info.flags |= SDL_COPY_MODULATE_ALPHA;
    } else {
        surface->map->info.flags &= ~SDL_COPY_MODULATE_ALPHA;
    }
    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }
    return 0;
}

int
SDL_GetSurfaceAlphaMod(SDL_Surface * surface, Uint8 * alpha)
{
    if (!surface) {
        return -1;
    }

    if (alpha) {
        *alpha = surface->map->info.a;
    }
    return 0;
}

int
SDL_SetSurfaceBlendMode(SDL_Surface * surface, int blendMode)
{
    int flags, status;

    if (!surface) {
        return -1;
    }

    status = 0;
    flags = surface->map->info.flags;
    surface->map->info.flags &=
        ~(SDL_COPY_MASK | SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD);
    switch (blendMode) {
    case SDL_BLENDMODE_NONE:
        break;
    case SDL_BLENDMODE_MASK:
        surface->map->info.flags |= SDL_COPY_MASK;
        break;
    case SDL_BLENDMODE_BLEND:
        surface->map->info.flags |= SDL_COPY_BLEND;
        break;
    case SDL_BLENDMODE_ADD:
        surface->map->info.flags |= SDL_COPY_ADD;
        break;
    case SDL_BLENDMODE_MOD:
        surface->map->info.flags |= SDL_COPY_MOD;
        break;
    default:
        SDL_Unsupported();
        status = -1;
        break;
    }

    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }

    /* Compatibility mode */
    if (surface->map->info.flags & SDL_COPY_BLEND) {
        surface->flags |= SDL_SRCALPHA;
    } else {
        surface->flags &= ~SDL_SRCALPHA;
    }

    return status;
}

int
SDL_GetSurfaceBlendMode(SDL_Surface * surface, int *blendMode)
{
    if (!surface) {
        return -1;
    }

    if (!blendMode) {
        return 0;
    }

    switch (surface->map->
            info.flags & (SDL_COPY_MASK | SDL_COPY_BLEND | SDL_COPY_ADD |
                          SDL_COPY_MOD)) {
    case SDL_COPY_MASK:
        *blendMode = SDL_BLENDMODE_MASK;
        break;
    case SDL_COPY_BLEND:
        *blendMode = SDL_BLENDMODE_BLEND;
        break;
    case SDL_COPY_ADD:
        *blendMode = SDL_BLENDMODE_ADD;
        break;
    case SDL_COPY_MOD:
        *blendMode = SDL_BLENDMODE_MOD;
        break;
    default:
        *blendMode = SDL_BLENDMODE_NONE;
        break;
    }
    return 0;
}

int
SDL_SetSurfaceScaleMode(SDL_Surface * surface, int scaleMode)
{
    int flags, status;

    if (!surface) {
        return -1;
    }

    status = 0;
    flags = surface->map->info.flags;
    surface->map->info.flags &= ~(SDL_COPY_NEAREST);
    switch (scaleMode) {
    case SDL_TEXTURESCALEMODE_NONE:
        break;
    case SDL_TEXTURESCALEMODE_FAST:
        surface->map->info.flags |= SDL_COPY_NEAREST;
        break;
    case SDL_TEXTURESCALEMODE_SLOW:
    case SDL_TEXTURESCALEMODE_BEST:
        SDL_Unsupported();
        surface->map->info.flags |= SDL_COPY_NEAREST;
        status = -1;
        break;
    default:
        SDL_Unsupported();
        status = -1;
        break;
    }

    if (surface->map->info.flags != flags) {
        SDL_InvalidateMap(surface->map);
    }
    return status;
}

int
SDL_GetSurfaceScaleMode(SDL_Surface * surface, int *scaleMode)
{
    if (!surface) {
        return -1;
    }

    if (!scaleMode) {
        return 0;
    }

    switch (surface->map->info.flags & SDL_COPY_NEAREST) {
    case SDL_COPY_NEAREST:
        *scaleMode = SDL_TEXTURESCALEMODE_FAST;
        break;
    default:
        *scaleMode = SDL_TEXTURESCALEMODE_NONE;
        break;
    }
    return 0;
}

SDL_bool
SDL_SetClipRect(SDL_Surface * surface, const SDL_Rect * rect)
{
    SDL_Rect full_rect;

    /* Don't do anything if there's no surface to act on */
    if (!surface) {
        return SDL_FALSE;
    }

    /* Set up the full surface rectangle */
    full_rect.x = 0;
    full_rect.y = 0;
    full_rect.w = surface->w;
    full_rect.h = surface->h;

    /* Set the clipping rectangle */
    if (!rect) {
        surface->clip_rect = full_rect;
        return 1;
    }
    return SDL_IntersectRect(rect, &full_rect, &surface->clip_rect);
}

void
SDL_GetClipRect(SDL_Surface * surface, SDL_Rect * rect)
{
    if (surface && rect) {
        *rect = surface->clip_rect;
    }
}

/* 
 * Set up a blit between two surfaces -- split into three parts:
 * The upper part, SDL_UpperBlit(), performs clipping and rectangle 
 * verification.  The lower part is a pointer to a low level
 * accelerated blitting function.
 *
 * These parts are separated out and each used internally by this 
 * library in the optimimum places.  They are exported so that if
 * you know exactly what you are doing, you can optimize your code
 * by calling the one(s) you need.
 */
int
SDL_LowerBlit(SDL_Surface * src, SDL_Rect * srcrect,
              SDL_Surface * dst, SDL_Rect * dstrect)
{
    /* Check to make sure the blit mapping is valid */
    if ((src->map->dst != dst) ||
        (src->map->dst->format_version != src->map->format_version)) {
        if (SDL_MapSurface(src, dst) < 0) {
            return (-1);
        }
        /* just here for debugging */
/*         printf */
/*             ("src = 0x%08X src->flags = %08X src->map->info.flags = %08x\ndst = 0x%08X dst->flags = %08X dst->map->info.flags = %08X\nsrc->map->blit = 0x%08x\n", */
/*              src, dst->flags, src->map->info.flags, dst, dst->flags, */
/*              dst->map->info.flags, src->map->blit); */
    }
    return (src->map->blit(src, srcrect, dst, dstrect));
}


int
SDL_UpperBlit(SDL_Surface * src, SDL_Rect * srcrect,
              SDL_Surface * dst, SDL_Rect * dstrect)
{
    SDL_Rect fulldst;
    int srcx, srcy, w, h;

    /* Make sure the surfaces aren't locked */
    if (!src || !dst) {
        SDL_SetError("SDL_UpperBlit: passed a NULL surface");
        return (-1);
    }
    if (src->locked || dst->locked) {
        SDL_SetError("Surfaces must not be locked during blit");
        return (-1);
    }

    /* If the destination rectangle is NULL, use the entire dest surface */
    if (dstrect == NULL) {
        fulldst.x = fulldst.y = 0;
        dstrect = &fulldst;
    }

    /* clip the source rectangle to the source surface */
    if (srcrect) {
        int maxw, maxh;

        srcx = srcrect->x;
        w = srcrect->w;
        if (srcx < 0) {
            w += srcx;
            dstrect->x -= srcx;
            srcx = 0;
        }
        maxw = src->w - srcx;
        if (maxw < w)
            w = maxw;

        srcy = srcrect->y;
        h = srcrect->h;
        if (srcy < 0) {
            h += srcy;
            dstrect->y -= srcy;
            srcy = 0;
        }
        maxh = src->h - srcy;
        if (maxh < h)
            h = maxh;

    } else {
        srcx = srcy = 0;
        w = src->w;
        h = src->h;
    }

    /* clip the destination rectangle against the clip rectangle */
    {
        SDL_Rect *clip = &dst->clip_rect;
        int dx, dy;

        dx = clip->x - dstrect->x;
        if (dx > 0) {
            w -= dx;
            dstrect->x += dx;
            srcx += dx;
        }
        dx = dstrect->x + w - clip->x - clip->w;
        if (dx > 0)
            w -= dx;

        dy = clip->y - dstrect->y;
        if (dy > 0) {
            h -= dy;
            dstrect->y += dy;
            srcy += dy;
        }
        dy = dstrect->y + h - clip->y - clip->h;
        if (dy > 0)
            h -= dy;
    }

    if (w > 0 && h > 0) {
        SDL_Rect sr;
        sr.x = srcx;
        sr.y = srcy;
        sr.w = dstrect->w = w;
        sr.h = dstrect->h = h;
        return SDL_LowerBlit(src, &sr, dst, dstrect);
    }
    dstrect->w = dstrect->h = 0;
    return 0;
}

/*
 * Lock a surface to directly access the pixels
 */
int
SDL_LockSurface(SDL_Surface * surface)
{
    if (!surface->locked) {
        /* Perform the lock */
        if (surface->flags & SDL_RLEACCEL) {
            SDL_UnRLESurface(surface, 1);
            surface->flags |= SDL_RLEACCEL;     /* save accel'd state */
        }
    }

    /* Increment the surface lock count, for recursive locks */
    ++surface->locked;

    /* Ready to go.. */
    return (0);
}

/*
 * Unlock a previously locked surface
 */
void
SDL_UnlockSurface(SDL_Surface * surface)
{
    /* Only perform an unlock if we are locked */
    if (!surface->locked || (--surface->locked > 0)) {
        return;
    }

    /* Update RLE encoded surface with new data */
    if ((surface->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {
        surface->flags &= ~SDL_RLEACCEL;        /* stop lying */
        SDL_RLESurface(surface);
    }
}

/* 
 * Convert a surface into the specified pixel format.
 */
SDL_Surface *
SDL_ConvertSurface(SDL_Surface * surface, SDL_PixelFormat * format,
                   Uint32 flags)
{
    SDL_Surface *convert;
    Uint32 copy_flags;
    SDL_Rect bounds;

    /* Check for empty destination palette! (results in empty image) */
    if (format->palette != NULL) {
        int i;
        for (i = 0; i < format->palette->ncolors; ++i) {
            if ((format->palette->colors[i].r != 0xFF) ||
                (format->palette->colors[i].g != 0xFF) ||
                (format->palette->colors[i].b != 0xFF))
                break;
        }
        if (i == format->palette->ncolors) {
            SDL_SetError("Empty destination palette");
            return (NULL);
        }
    }

    /* Create a new surface with the desired format */
    convert = SDL_CreateRGBSurface(flags, surface->w, surface->h,
                                   format->BitsPerPixel, format->Rmask,
                                   format->Gmask, format->Bmask,
                                   format->Amask);
    if (convert == NULL) {
        return (NULL);
    }

    /* Copy the palette if any */
    if (format->palette && convert->format->palette) {
        SDL_memcpy(convert->format->palette->colors,
                   format->palette->colors,
                   format->palette->ncolors * sizeof(SDL_Color));
        convert->format->palette->ncolors = format->palette->ncolors;
    }

    /* Save the original copy flags */
    copy_flags = surface->map->info.flags;
    surface->map->info.flags = 0;

    /* Copy over the image data */
    bounds.x = 0;
    bounds.y = 0;
    bounds.w = surface->w;
    bounds.h = surface->h;
    SDL_LowerBlit(surface, &bounds, convert, &bounds);

    /* Clean up the original surface, and update converted surface */
    convert->map->info.r = surface->map->info.r;
    convert->map->info.g = surface->map->info.g;
    convert->map->info.b = surface->map->info.b;
    convert->map->info.a = surface->map->info.a;
    convert->map->info.flags =
        (copy_flags &
         ~(SDL_COPY_COLORKEY | SDL_COPY_BLEND
           | SDL_COPY_RLE_DESIRED | SDL_COPY_RLE_COLORKEY |
           SDL_COPY_RLE_ALPHAKEY));
    surface->map->info.flags = copy_flags;
    if (copy_flags & SDL_COPY_COLORKEY) {
        Uint8 keyR, keyG, keyB, keyA;

        SDL_GetRGBA(surface->map->info.colorkey, surface->format, &keyR,
                    &keyG, &keyB, &keyA);
        SDL_SetColorKey(convert, 1,
                        SDL_MapRGBA(convert->format, keyR, keyG, keyB, keyA));
        /* This is needed when converting for 3D texture upload */
        SDL_ConvertColorkeyToAlpha(convert);
    }
    SDL_SetClipRect(convert, &surface->clip_rect);

    /* Enable alpha blending by default if the new surface has an
     * alpha channel or alpha modulation */
    if ((surface->format->Amask && format->Amask) ||
        (copy_flags & SDL_COPY_MODULATE_ALPHA)) {
        SDL_SetSurfaceBlendMode(convert, SDL_BLENDMODE_BLEND);
    }
    if ((copy_flags & SDL_COPY_RLE_DESIRED) || (flags & SDL_RLEACCEL)) {
        SDL_SetSurfaceRLE(convert, SDL_RLEACCEL);
    }

    /* We're ready to go! */
    return (convert);
}

/*
 * Free a surface created by the above function.
 */
void
SDL_FreeSurface(SDL_Surface * surface)
{
    if (surface == NULL) {
        return;
    }
    if (--surface->refcount > 0) {
        return;
    }
    while (surface->locked > 0) {
        SDL_UnlockSurface(surface);
    }
    if (surface->flags & SDL_RLEACCEL) {
        SDL_UnRLESurface(surface, 0);
    }
    if (surface->format) {
        SDL_SetSurfacePalette(surface, NULL);
        SDL_FreeFormat(surface->format);
        surface->format = NULL;
    }
    if (surface->map != NULL) {
        SDL_FreeBlitMap(surface->map);
        surface->map = NULL;
    }
    if (surface->pixels && ((surface->flags & SDL_PREALLOC) != SDL_PREALLOC)) {
        SDL_free(surface->pixels);
    }
    SDL_free(surface);
#ifdef CHECK_LEAKS
    --surfaces_allocated;
#endif
}

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