Re: filling area by color atack safety

Malcolm McLean wrote:

On 16/03/2024 15:09, Malcolm McLean wrote:

On 16/03/2024 14:40, David Brown wrote:

On 16/03/2024 12:33, Malcolm McLean wrote:
>

And here's some code I wrote a while ago. Use that as a pattern. But
not sure how well it works. Haven't used it for a long time.
>
https://github.com/MalcolmMcLean/binaryimagelibrary/blob/master/drawbinary.c
>
>

>
Your implementation is a mess, /vastly/ more difficult to prove
correct than the OP's original one, and unlikely to be very much
faster (it will certainly scale in the same way in both time and
memory usage).
>

Now is this David Brown being David Borwn, ot its it actaully ture?

>

And I need to run some tests, don't I?
>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
>
int floodfill_r(unsigned char *grey, int width, int height, int x, int y,
unsigned char target, unsigned char dest)
{
    if (x < 0 || x >= width || y < 0 || y >= height)
      return 0;
    if (grey[y*width+x] != target)
      return 0;
    grey[y*width+x] = dest;
    floodfill_r(grey, width, height, x - 1, y, target, dest);
    floodfill_r(grey, width, height, x + 1, y, target, dest);
    floodfill_r(grey, width, height, x, y - 1, target, dest);
    floodfill_r(grey, width, height, x, y + 1, target, dest);
>
    return 0;
}
>

if someone would write simpler version i would write
recolorize_pixel_chain(int x, int y)
{
   if(map[y][x]==color_to_replace)
   {
    map[y][x]=replacement_color);
    recolorize_pixel_chain(x+1, y);
    recolorize_pixel_chain(x-1, y);
    recolorize_pixel_chain(x, y+1);
    recolorize_pixel_chain(x, y-1);
    }
}
but from practical coding the one with longer names is more practical imo - but this one above is more 'presenting'