Copy from a surface to another surface

NighTiger · June 5, 2003, 1:55pm

Hi guy,
I wrote more e-mails for this problem but anyone isn’t published.
I hope that will come published.
The problem is very simple… I can’t copy the result to a_tiles[i] from
finalbmp.
tnx

PS
Following you can find the unfinished work

int main ( int argc, char* argv[] )
{
SDL_Surface bmp, **a_tiles, finalbmp;
SDL_Rect src, dst;
Uint32 rmask, gmask, bmask, amask;
Uint32 a_map, n_square;
Uint8 r[3232], g[3232], b[3232], a[3232], R[3232], G[3232],
B[3232], A[32*32];
int img_w, img_h ,n_tile, x, y, i;

//////////////////////////////////////////////////////////////////////
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0xff000000;
gmask = 0x00ff0000;
bmask = 0x0000ff00;
amask = 0x000000ff;
#else
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
#endif
//////////////////////////////////////////////////////////////////////

if ( SDL_Init(SDL_INIT_VIDEO) < 0 )
{
fprintf(stderr, “Impossibile abilitare le SDL: %s.\n”, SDL_GetError());
return(1);
}

bmp = SDL_LoadBMP(“penguin.bmp”);

if ( bmp == NULL )
{
fprintf(stderr, “Impossibile caricare l’immagine: penguin.bmp.\n”);
return(1);
}

img_w = bmp->w / 32;
img_h = bmp->h / 32;
n_square = img_w * img_h;

a_tiles = calloc( n_square, sizeof(SDL_Surface*) );

a_map = calloc( n_square, sizeof(Uint32) );

src.w = 32;
src.h = 32;

dst.w = 32;
dst.h = 32;
dst.x = 0;
dst.y = 0;

for ( x = 0, n_tile = 0; x < img_w; x++, n_tile++ )
{
for ( y = 0; y < img_h; y++ )
{

  src.x = x * 32;
  src.y = y * 32;

  a_tiles[n_tile] = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32, 32,

rmask, gmask, bmask, amask);

  if ( a_tiles[n_tile] == NULL )
  {
    fprintf(stderr, "Impossibile creare la surface: %s.\n",

SDL_GetError());
return(1);
}

  SDL_BlitSurface(bmp, &src, a_tiles[n_tile], &dst);

/*

*/
}
}

finalbmp = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32*n_tile, 32, rmask,
gmask, bmask, amask);

src.x = 0;
src.y = 0;

for (i = 0; i < n_tile; i++)
{
dst.y = i * 32;
SDL_BlitSurface (a_tiles[i], &src, finalbmp, &dst);
}

SDL_SaveBMP(finalbmp, “prova.bmp”);

SDL_FreeSurface(bmp);
SDL_FreeSurface(finalbmp);

free(a_map);
free(a_tiles);

return(0);
}

Julien_Pauty · June 6, 2003, 1:20am

Hi what exactly do you mean by “I can’t copy the result to a_tiles[i] from
finalbmp”, is it crashing ? In your code you copy from a_tile to finalbmp.
To find where the problem is, try to display intermediate surface to see if
everything is going well.

I think the problem is with your n_tile variable. You should increment it in
the y loop, otherwise you copy several image in the same array cell. And
there will be some surface lost in the memory. If it is clear here is the
code modification i sugest :

n_tile = 0;
for ( x = 0; x < img_w; x++)
{
for ( y = 0; y < img_h; y++ )
{
…;
SDL_BlitSurface(bmp, &src, a_tiles[n_tile], &dst);
n_tile++;
}
}

I haven’t checked the rest of the code

Finally, you should start learning some debugging technique to find such
problems yourself, like using GDB or putting printf in your code.

Julien> ----- Original Message -----

From: nightiger_spp@libero.it (NighTiger)
To:
Cc:
Sent: Thursday, June 05, 2003 10:53 PM
Subject: [SDL] Copy from a surface to another surface
Hi guy,
I wrote more e-mails for this problem but anyone isn’t published.
I hope that will come published.
The problem is very simple… I can’t copy the result to a_tiles[i] from
finalbmp.
tnx

PS
Following you can find the unfinished work

int main ( int argc, char* argv[] )
{
SDL_Surface bmp, **a_tiles, finalbmp;
SDL_Rect src, dst;
Uint32 rmask, gmask, bmask, amask;
Uint32 a_map, n_square;
Uint8 r[3232], g[3232], b[3232], a[3232], R[3232], G[3232],
B[3232], A[32*32];
int img_w, img_h ,n_tile, x, y, i;

//////////////////////////////////////////////////////////////////////
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0xff000000;
gmask = 0x00ff0000;
bmask = 0x0000ff00;
amask = 0x000000ff;
#else
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
#endif
//////////////////////////////////////////////////////////////////////

if ( SDL_Init(SDL_INIT_VIDEO) < 0 )
{
fprintf(stderr, “Impossibile abilitare le SDL: %s.\n”,
SDL_GetError());
return(1);
}

bmp = SDL_LoadBMP(“penguin.bmp”);

if ( bmp == NULL )
{
fprintf(stderr, “Impossibile caricare l’immagine: penguin.bmp.\n”);
return(1);
}

img_w = bmp->w / 32;
img_h = bmp->h / 32;
n_square = img_w * img_h;

a_tiles = calloc( n_square, sizeof(SDL_Surface*) );

a_map = calloc( n_square, sizeof(Uint32) );

src.w = 32;
src.h = 32;

dst.w = 32;
dst.h = 32;
dst.x = 0;
dst.y = 0;

for ( x = 0, n_tile = 0; x < img_w; x++, n_tile++ )
{
for ( y = 0; y < img_h; y++ )
{
  src.x = x * 32;
  src.y = y * 32;

  a_tiles[n_tile] = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32, 32,
rmask, gmask, bmask, amask);
  if ( a_tiles[n_tile] == NULL )
  {
    fprintf(stderr, "Impossibile creare la surface: %s.\n",
SDL_GetError());
return(1);
}
  SDL_BlitSurface(bmp, &src, a_tiles[n_tile], &dst);
/*

*/
}
}

finalbmp = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32*n_tile, 32, rmask,
gmask, bmask, amask);

src.x = 0;
src.y = 0;

for (i = 0; i < n_tile; i++)
{
dst.y = i * 32;
SDL_BlitSurface (a_tiles[i], &src, finalbmp, &dst);
}

SDL_SaveBMP(finalbmp, “prova.bmp”);

SDL_FreeSurface(bmp);
SDL_FreeSurface(finalbmp);

free(a_map);
free(a_tiles);

return(0);
}

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

John_Popplewell · June 6, 2003, 1:29pm

Hi,

from the docs for SDL_CreateRGBSurface():

“Note: If an alpha-channel is specified (that is, if Amask is nonzero), then
the SDL_SRCALPHA flag is automatically set. You may remove this flag by
calling SDL_SetAlpha after surface creation.”

This isn’t very obvious (unless you carefully read the docs) and
you aren’t the first to be caught by this…-------------------------------------------------------------
…
for ( x = 0, n_tile = 0; x < img_w; x++ )
{
for ( y = 0; y < img_h; y++, n_tile++ ) // increment here instead!
{

  src.x = x * 32;
  src.y = y * 32;

  a_tiles[n_tile] = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32,
                                 32,rmask, gmask, bmask, amask);

  SDL_SetAlpha( a_tiles[n_tile], 0, 0 );// unset SDL_SRCALPHA

  if ( a_tiles[n_tile] == NULL )
  {
    fprintf(stderr, "Impossibile creare la surface: %s.\n",
                                               SDL_GetError());
    return(1);
  }
  SDL_BlitSurface(bmp, &src, a_tiles[n_tile], &dst);
}

}
…

[Note that I have moved n_tile++ to the correct place.]

Also, you shouldn’t really call SDL_CreateRGBSurface() until after
you have called SDL_SetVideoMode(). Again, see the docs:

http://sdldoc.csn.ul.ie/sdlcreatergbsurface.php

Good luck,

cheers,
John.

----- Original Message -----
From: nightiger_spp@libero.it (NighTiger)
To:
Cc:
Sent: Thursday, June 05, 2003 9:53 PM
Subject: [SDL] Copy from a surface to another surface
Hi guy,
I wrote more e-mails for this problem but anyone isn’t published.
I hope that will come published.
The problem is very simple… I can’t copy the result to a_tiles[i] from
finalbmp.
tnx

PS
Following you can find the unfinished work

int main ( int argc, char* argv[] )
{
SDL_Surface bmp, **a_tiles, finalbmp;
SDL_Rect src, dst;
Uint32 rmask, gmask, bmask, amask;
Uint32 a_map, n_square;
Uint8 r[3232], g[3232], b[3232], a[3232], R[3232], G[3232],
B[3232], A[32*32];
int img_w, img_h ,n_tile, x, y, i;

//////////////////////////////////////////////////////////////////////
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0xff000000;
gmask = 0x00ff0000;
bmask = 0x0000ff00;
amask = 0x000000ff;
#else
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
#endif
//////////////////////////////////////////////////////////////////////

if ( SDL_Init(SDL_INIT_VIDEO) < 0 )
{
fprintf(stderr, “Impossibile abilitare le SDL: %s.\n”,
SDL_GetError());
return(1);
}

bmp = SDL_LoadBMP(“penguin.bmp”);

if ( bmp == NULL )
{
fprintf(stderr, “Impossibile caricare l’immagine: penguin.bmp.\n”);
return(1);
}

img_w = bmp->w / 32;
img_h = bmp->h / 32;
n_square = img_w * img_h;

a_tiles = calloc( n_square, sizeof(SDL_Surface*) );

a_map = calloc( n_square, sizeof(Uint32) );

src.w = 32;
src.h = 32;

dst.w = 32;
dst.h = 32;
dst.x = 0;
dst.y = 0;

for ( x = 0, n_tile = 0; x < img_w; x++, n_tile++ )
{
for ( y = 0; y < img_h; y++ )
{
  src.x = x * 32;
  src.y = y * 32;

  a_tiles[n_tile] = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32, 32,
rmask, gmask, bmask, amask);
  if ( a_tiles[n_tile] == NULL )
  {
    fprintf(stderr, "Impossibile creare la surface: %s.\n",
SDL_GetError());
return(1);
}
  SDL_BlitSurface(bmp, &src, a_tiles[n_tile], &dst);
/*

*/
}
}

finalbmp = SDL_CreateRGBSurface(SDL_HWSURFACE, 32, 32*n_tile, 32, rmask,
gmask, bmask, amask);

src.x = 0;
src.y = 0;

for (i = 0; i < n_tile; i++)
{
dst.y = i * 32;
SDL_BlitSurface (a_tiles[i], &src, finalbmp, &dst);
}

SDL_SaveBMP(finalbmp, “prova.bmp”);

SDL_FreeSurface(bmp);
SDL_FreeSurface(finalbmp);

free(a_map);
free(a_tiles);

return(0);
}

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

NighTiger · June 7, 2003, 1:41am

Hi Julien,
I had wrote wrong.
I copy from a_tiles[i] to finalbmp.
Finalbmp have the correct dimension but is all black.> Hi what exactly do you mean by "I can’t copy the result to a_tiles[i]

from finalbmp", is it crashing ? In your code you copy from a_tile to
finalbmp.
To find where the problem is, try to display intermediate surface to
see if everything is going well.

NighTiger · June 7, 2003, 2:01am

Hi John Popplewell,
your way is right, now the program work fine.
tnx

Copy from a surface to another surface

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