view test/testbitmap.c @ 638:b0108e9dea53

Date: Sun, 11 May 2003 19:59:06 +0300 From: Pasi K?rkk?inen Subject: [PATCH] fix SDL OpenGL segfault with DRI/Mesa drivers and Glew Hello! The attached patch fixes a bug in SDL which causes SDL to crash in X11_GL_Shutdown() if you are using DRI/Mesa drivers AND glew (http://glew.sf.net). The bug is caused by a namespace collision affecting dlsym() to fetch wrong pointer for glXReleaseBuffersMESA() (uninitialized pointer from glew because the extension is NOT supported by the driver) and then SDL calling it in X11_GL_Shutdown(). SDL should check if the glXReleaseBuffersMESA() is really supported by the driver (from the extensions string) before calling it. Attached patch adds extension string parsing to check if glXReleaseBuffersMESA() is really supported (and this way prevents the segfault). Availability of the extensions should be _always_ checked from the extensions string rather than using dlsym()! Please add it to the next version of SDL. Thanks to gltron and author of glew to help fixing this.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 28 Jun 2003 17:27:33 +0000
parents 74212992fb08
children 609543e2b3a1
line wrap: on
line source


/* Simple program:  Test bitmap blits */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "SDL.h"
#include "picture.xbm"

SDL_Surface *LoadXBM(SDL_Surface *screen, int w, int h, Uint8 *bits)
{
	SDL_Surface *bitmap;
	Uint8 *line;

	/* Allocate the bitmap */
	bitmap = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 1, 0, 0, 0, 0);
	if ( bitmap == NULL ) {
		fprintf(stderr, "Couldn't allocate bitmap: %s\n",
						SDL_GetError());
		return(NULL);
	}

	/* Copy the pixels */
	line = (Uint8 *)bitmap->pixels;
	w = (w+7)/8;
	while ( h-- ) {
		memcpy(line, bits, w);
		/* X11 Bitmap images have the bits reversed */
		{ int i, j; Uint8 *buf, byte;
			for ( buf=line, i=0; i<w; ++i, ++buf ) {
				byte = *buf;
				*buf = 0;
				for ( j=7; j>=0; --j ) {
					*buf |= (byte&0x01)<<j;
					byte >>= 1;
				}
			}
		}
		line += bitmap->pitch;
		bits += w;
	}
	return(bitmap);
}

int main(int argc, char *argv[])
{
	SDL_Surface *screen;
	SDL_Surface *bitmap;
	Uint8  video_bpp;
	Uint32 videoflags;
	Uint8 *buffer;
	int i, done;
	SDL_Event event;

	/* Initialize SDL */
	if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		exit(1);
	}
	atexit(SDL_Quit);

	video_bpp = 0;
	videoflags = SDL_SWSURFACE;
	while ( argc > 1 ) {
		--argc;
		if ( strcmp(argv[argc-1], "-bpp") == 0 ) {
			video_bpp = atoi(argv[argc]);
			--argc;
		} else
		if ( strcmp(argv[argc], "-warp") == 0 ) {
			videoflags |= SDL_HWPALETTE;
		} else
		if ( strcmp(argv[argc], "-hw") == 0 ) {
			videoflags |= SDL_HWSURFACE;
		} else
		if ( strcmp(argv[argc], "-fullscreen") == 0 ) {
			videoflags |= SDL_FULLSCREEN;
		} else {
			fprintf(stderr,
			"Usage: %s [-bpp N] [-warp] [-hw] [-fullscreen]\n",
								argv[0]);
			exit(1);
		}
	}

	/* Set 640x480 video mode */
	if ( (screen=SDL_SetVideoMode(640,480,video_bpp,videoflags)) == NULL ) {
		fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
						video_bpp, SDL_GetError());
		exit(2);
	}

	/* Set the surface pixels and refresh! */
	if ( SDL_LockSurface(screen) < 0 ) {
		fprintf(stderr, "Couldn't lock the display surface: %s\n",
							SDL_GetError());
		exit(2);
	}
	buffer=(Uint8 *)screen->pixels;
	for ( i=0; i<screen->h; ++i ) {
		memset(buffer,(i*255)/screen->h, screen->pitch);
		buffer += screen->pitch;
	}
	SDL_UnlockSurface(screen);
	SDL_UpdateRect(screen, 0, 0, 0, 0);

	/* Load the bitmap */
	bitmap = LoadXBM(screen, picture_width, picture_height,
					(Uint8 *)picture_bits);
	if ( bitmap == NULL ) {
		exit(1);
	}

	/* Wait for a keystroke */
	done = 0;
	while ( !done ) {
		/* Check for events */
		while ( SDL_PollEvent(&event) ) {
			switch (event.type) {
				case SDL_MOUSEBUTTONDOWN: {
					SDL_Rect dst;

					dst.x = event.button.x - bitmap->w/2;
					dst.y = event.button.y - bitmap->h/2;
					dst.w = bitmap->w;
					dst.h = bitmap->h;
					SDL_BlitSurface(bitmap, NULL,
								screen, &dst);
					SDL_UpdateRects(screen,1,&dst);
					}
					break;
				case SDL_KEYDOWN:
					/* Any key press quits the app... */
					done = 1;
					break;
				case SDL_QUIT:
					done = 1;
					break;
				default:
					break;
			}
		}
	}
	SDL_FreeSurface(bitmap);
	return(0);
}