Re: filling area by color atack safety

Peter 'Shaggy' Haywood wrote:

Groovy hepcat Lew Pitcher was jivin' in comp.lang.c on Mon, 18 Mar 2024
01:27 am. It's a cool scene! Dig it.
>

On 16/03/2024 04:11, fir wrote:

>
   [Snip.]
>

int RecolorizePixelAndAdjacentOnes(int x, int y, unsigned old_color,
unsigned new_color)
{
  if(old_color == new_color) return 0;
>
  if(XYIsInScreen( x,  y))
  if(GetPixelUnsafe(x,y)==old_color)
  {
  SetPixelSafe(x,y,new_color);
  RecolorizePixelAndAdjacentOnes(x+1, y,  old_color, new_color);
  RecolorizePixelAndAdjacentOnes(x-1, y,  old_color, new_color);
  RecolorizePixelAndAdjacentOnes(x, y-1,  old_color, new_color);
  RecolorizePixelAndAdjacentOnes(x, y+1,  old_color, new_color);
  return 1;
  }
>
  return 0;
}

>
   [Snippity doo dah.]
>

Take fir's example code above; a simple single call to
RecolorizePixelAndAdjacentOnes() will effectively recolour the
origin cell multiple times, because of how the recursion is handled.

>
   No, I don't think so. You seem to have missed the fact that it checks
the colour of the "current" pixel, and only continues (setting new
colour & recursing) if it is the old colour.
   Of course, I'm infering (guessing) the functionality, at least
partially (Unsafe? Safe?), of GetPixelUnsafe() and SetPixelSafe() based
on their names.
>
   [Snip Lew's examples.]
>

Safe and Unsafe means that Safe checks if the x,y is in the array of pixels, when Unsafe just writes without checking - i draw in array of unsigned 32 bit ARGB or GBRA (never remeber) pixels - then i blit that
'bitmap' on window client size as it can be done in winapi
here are exact code
inline void SetPixelUnsafe(int x, int y, unsigned color)
{
   extern int frame_size_x ;
   extern int frame_size_y ;
   extern unsigned int* frame_bitmap ;
   frame_bitmap[y*frame_size_x+x]=color;
}
inline void SetPixelSafe(int x, int y, unsigned color)
{
    //  if(frame==0) ERROR_EXIT("frame is zero in setpixelsafe ");
      if(x<0)              return;
      if(x>frame_size_x-1) return;
      if(y<0)              return;
      if(y>frame_size_y-1) return;
      frame_bitmap[y*frame_size_x+x]=color;
}
there was soem mistake in that function before as if i check already i should be using Unsafe versions of setpixel and getpixel but i tested this for work not for optimisation so i didnt care