Stupid problem with blitting

SDL Development
1

Hi

I have never had any problems with drawing in any of my games. Then on the
otherhand, most of them have been 3D OpenGL driven… But I remeber doing
some early games in 2D long back. But now when I sat down at work to greate
a simple 2D game to test a system we are developing I get SDL saying (when
using the draw_bmp function from the libsdl site) “BlitSurface error:
Surfaces must not be locked during blit”

Now, the thing is… I don’t lock ANY surface ANYWHERE… So whats wrong?

A glance at the code:

(mpSurface is a SDL_Surface in test_game. The system will then take that and
blit it to a surface called screen later on…)

I set the videomode to the following:
screen = SDL_SetVideoMode(800, 600, 32,
SDL_HWSURFACE|SDL_ANYFORMAT|SDL_DOUBLEBUF);

void TestGame::PlayRound()
{
int computer_hand = 0;

computer_hand = (rand()%3);
int human_hand = GetPlayerHand();

//cout << "Du har: ";
switch( human_hand )
{
case 0 : DisplayBmp(“stone.bmp”, 100, 100); break;
case 1 : DisplayBmp(“sic.bmp”, 100, 100); break;
case 2 : DisplayBmp(“bag.bmp”, 100, 100); break;
}

//cout << "Datorn har: ";
switch( computer_hand )
{
case 0 : DisplayBmp(“stone.bmp”, 200, 100); break;
case 1 : DisplayBmp(“sic.bmp”, 200, 100); break;
case 2 : DisplayBmp(“bag.bmp”, 200, 100); break;
}

if ( human_hand == computer_hand )
{
cout << “Draw…” << endl << endl;
}
else if ( human_hand == 0 && computer_hand != 2 )
{
cout << “You win!” << endl << endl;
}
else if ( human_hand == 1 && computer_hand != 0 )
{
cout << “You win!” << endl << endl;
}
else if ( human_hand == 2 && computer_hand != 1 )
{
cout << “You win!” << endl << endl;
}
else
{
cout << Computer wins!" << endl << endl;
}

}

void TestGame::DisplayBmp(char *pFileName, int posX, int posY)
{
SDL_Surface *image;

/* Load the BMP file into a surface */
image = SDL_LoadBMP(pFileName);
if (image == NULL)
{
    fprintf(stderr, "Couldn't load %s: %s\n", pFileName,

SDL_GetError());
return;
}

/*
 * Palettized screen modes will have a default palette (a standard
 * 8*8*4 colour cube), but if the image is palettized as well we can
 * use that palette for a nicer colour matching
 */
if (image->format->palette && mpSurface->format->palette)
{
SDL_SetColors(mpSurface, image->format->palette->colors, 0,
              image->format->palette->ncolors);
}

/* Blit onto the screen surface */
if(SDL_BlitSurface(image, NULL, mpSurface, NULL) < 0)
    fprintf(stderr, "BlitSurface error: %s\n", SDL_GetError());

SDL_UpdateRect(mpSurface, 0, 0, image->w, image->h);

/* Free the allocated BMP surface */
SDL_FreeSurface(image);

}

Best regards
Daniel_________________________________________________________________
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2

Damien Damien wrote:

to greate a simple 2D game to test a system we are developing I get SDL
saying (when using the draw_bmp function from the libsdl site)
“BlitSurface error: Surfaces must not be locked during blit”

Now, the thing is… I don’t lock ANY surface ANYWHERE… So whats wrong?

i’d doublecheck the value of the surface->locked attribute. if it’s not
zero the surface sure is locked. then try to find out when and where it
is getting set.

the code inside SDL is testing like this (inside the SDL_UpperBlit func)

if ( src->locked || dst->locked ) {
	SDL_SetError("Surfaces must not be locked during blit");
	return(-1);
}