Fillflood algo and SDL

Hi thank’s for your reply:
I send you a not recursive sdl function , I have found ( thank’s frank for this link :).

It’s seem to work , and don’t make any core dump.

void setPixels(SDL_Surface *s,int x,int y,Uint32 c);
Uint32 getPixels(SDL_Surface s,int x,int y);

  • A Seed Fill Algorithm
  • by Paul Heckbert
  • from “Graphics Gems”, Academic Press, 1990*
  • user provides pixelread() and pixelwrite() routines
    typedef struct {short y, xl, xr, dy;} Segment;


  • Filled horizontal segment of scanline y for xl<=x<=xr.
  • Parent segment was on line y-dy. dy=1 or -1

#define MAX 10000 /* max depth of stack */

#define PUSH(Y, XL, XR, DY,S) /* push new segment on stack */
if (sp<stack+MAX && Y+(DY)>=0 && Y+(DY)<=S->h)
{sp->y = Y; sp->xl = XL; sp->xr = XR; sp->dy = DY; sp++;}

#define POP(Y, XL, XR, DY) /* pop segment off stack */
{sp–; Y = sp->y+(DY = sp->dy); XL = sp->xl; XR = sp->xr;}


  • fill: set the pixel at (x,y) and all of its 4-connected neighbors

  • with the same pixel value to the new pixel value nv.

  • A 4-connected neighbor is a pixel above, below, left, or right of a
    void floodfill(SDL_Surface *win,int x,int y, Uint32 nv)
    int l, x1, x2, dy;
    Segment stack[MAX], sp = stack; / stack of filled segments */
    Uint32 ov=getPixels(win,x,y);

    if (x<0 || y<0 || x>=win->w || y>=win->h ) return;
    if (ov==nv) return;
    PUSH(y, x, x, 1,win); /* needed in some cases
    PUSH(y+1, x, x, -1,win); /
    seed segment (popped 1st) */

    while (sp>stack) {
    /* pop segment off stack and fill a neighboring scan line /
    POP(y, x1, x2, dy);

    * segment of scan line y-dy for x1<=x<=x2 was previously
    * now explore adjacent pixels in scan line y
    for (x=x1; x>=0 && getPixels(win,x, y)==ov; x–)
    if (x>=x1) goto skip;
    l = x+1;
    if (l<x1) PUSH(y, l, x1-1, -dy,win); /
    leak on left?
    x = x1+1;
    do {
    for (; x<=win->w && getPixels(win,x, y)==ov; x++)
    setPixels(win,x, y, nv);
    PUSH(y, l, x-1, dy,win);
    if (x>x2+1) PUSH(y, x2+1, x-1, -dy,win); /
    leak on
    right? */
    skip: for (x++; x<=x2 && getPixels(win,x, y)!=ov; x++);
    l = x;
    } while (x<=x2);