test/testbitmap.c
author Patrice Mandin <patmandin@gmail.com>
Thu, 19 Jan 2006 21:28:52 +0000
changeset 1257 448a9a64537b
parent 1151 be9c9c8f6d53
child 1662 782fd950bd46
child 1895 c121d94672cb
permissions -rw-r--r--
[PATCH] SDL_GetVideoMode() does not find best mode, part 2

Following commit 1.51, I come accross a problem when SDL must choose between
several video modes that could suit the one asked.

If I ask 320x240 with this list:
768x480 768x240 640x400 640x200 384x480 384x240 320x400 320x200

The smallest selectables modes are 384x240 and 320x400. And SDL choose the later
in this list, but 384x240 is more suitable. So I added a check to compare
the pixel count (surface) of modes, and select the one which has the smallest
pixel count.

In my example, 384x240 has 92160 pixels, and 320x400 has 128000 pixels. So now
SDL will choose 384x240 for the asked 320x240 mode.
     1 
     2 /* Simple program:  Test bitmap blits */
     3 
     4 #include <stdio.h>
     5 #include <stdlib.h>
     6 #include <string.h>
     7 
     8 #include "SDL.h"
     9 #include "picture.xbm"
    10 
    11 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
    12 static void quit(int rc)
    13 {
    14 	SDL_Quit();
    15 	exit(rc);
    16 }
    17 
    18 SDL_Surface *LoadXBM(SDL_Surface *screen, int w, int h, Uint8 *bits)
    19 {
    20 	SDL_Surface *bitmap;
    21 	Uint8 *line;
    22 
    23 	/* Allocate the bitmap */
    24 	bitmap = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 1, 0, 0, 0, 0);
    25 	if ( bitmap == NULL ) {
    26 		fprintf(stderr, "Couldn't allocate bitmap: %s\n",
    27 						SDL_GetError());
    28 		return(NULL);
    29 	}
    30 
    31 	/* Copy the pixels */
    32 	line = (Uint8 *)bitmap->pixels;
    33 	w = (w+7)/8;
    34 	while ( h-- ) {
    35 		memcpy(line, bits, w);
    36 		/* X11 Bitmap images have the bits reversed */
    37 		{ int i, j; Uint8 *buf, byte;
    38 			for ( buf=line, i=0; i<w; ++i, ++buf ) {
    39 				byte = *buf;
    40 				*buf = 0;
    41 				for ( j=7; j>=0; --j ) {
    42 					*buf |= (byte&0x01)<<j;
    43 					byte >>= 1;
    44 				}
    45 			}
    46 		}
    47 		line += bitmap->pitch;
    48 		bits += w;
    49 	}
    50 	return(bitmap);
    51 }
    52 
    53 int main(int argc, char *argv[])
    54 {
    55 	SDL_Surface *screen;
    56 	SDL_Surface *bitmap;
    57 	Uint8  video_bpp;
    58 	Uint32 videoflags;
    59 	Uint8 *buffer;
    60 	int i, k, done;
    61 	SDL_Event event;
    62 	Uint16 *buffer16;
    63         Uint16 color;
    64         Uint8  gradient;
    65 	SDL_Color palette[256];
    66 
    67 
    68 	/* Initialize SDL */
    69 	if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
    70 		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
    71 		return(1);
    72 	}
    73 
    74 	video_bpp = 0;
    75 	videoflags = SDL_SWSURFACE;
    76 	while ( argc > 1 ) {
    77 		--argc;
    78 		if ( strcmp(argv[argc-1], "-bpp") == 0 ) {
    79 			video_bpp = atoi(argv[argc]);
    80 			--argc;
    81 		} else
    82 		if ( strcmp(argv[argc], "-warp") == 0 ) {
    83 			videoflags |= SDL_HWPALETTE;
    84 		} else
    85 		if ( strcmp(argv[argc], "-hw") == 0 ) {
    86 			videoflags |= SDL_HWSURFACE;
    87 		} else
    88 		if ( strcmp(argv[argc], "-fullscreen") == 0 ) {
    89 			videoflags |= SDL_FULLSCREEN;
    90 		} else {
    91 			fprintf(stderr,
    92 			"Usage: %s [-bpp N] [-warp] [-hw] [-fullscreen]\n",
    93 								argv[0]);
    94 			quit(1);
    95 		}
    96 	}
    97 
    98 	/* Set 640x480 video mode */
    99 	if ( (screen=SDL_SetVideoMode(640,480,video_bpp,videoflags)) == NULL ) {
   100 		fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
   101 						video_bpp, SDL_GetError());
   102 		quit(2);
   103 	}
   104 
   105 	if (video_bpp==8) {
   106 		/* Set a gray colormap, reverse order from white to black */
   107 		for ( i=0; i<256; ++i ) {
   108 			palette[i].r = 255-i;
   109 			palette[i].g = 255-i;
   110 			palette[i].b = 255-i;
   111 		}
   112 		SDL_SetColors(screen, palette, 0, 256);
   113 	}
   114 
   115 	/* Set the surface pixels and refresh! */
   116 	if ( SDL_LockSurface(screen) < 0 ) {
   117 		fprintf(stderr, "Couldn't lock the display surface: %s\n",
   118 							SDL_GetError());
   119 		quit(2);
   120 	}
   121 	buffer=(Uint8 *)screen->pixels;
   122 	if (screen->format->BytesPerPixel!=2) {
   123         	for ( i=0; i<screen->h; ++i ) {
   124         		memset(buffer,(i*255)/screen->h, screen->pitch);
   125         		buffer += screen->pitch;
   126         	}
   127         }
   128         else
   129         {
   130 		for ( i=0; i<screen->h; ++i ) {
   131 			gradient=((i*255)/screen->h);
   132                         color = SDL_MapRGB(screen->format, gradient, gradient, gradient);
   133                         buffer16=(Uint16*)buffer;
   134                         for (k=0; k<screen->w; k++)
   135                         {
   136                             *(buffer16+k)=color;
   137                         }
   138 			buffer += screen->pitch;
   139 		}
   140         }
   141 	SDL_UnlockSurface(screen);
   142 	SDL_UpdateRect(screen, 0, 0, 0, 0);
   143 
   144 	/* Load the bitmap */
   145 	bitmap = LoadXBM(screen, picture_width, picture_height,
   146 					(Uint8 *)picture_bits);
   147 	if ( bitmap == NULL ) {
   148 		quit(1);
   149 	}
   150 
   151 	/* Wait for a keystroke */
   152 	done = 0;
   153 	while ( !done ) {
   154 		/* Check for events */
   155 		while ( SDL_PollEvent(&event) ) {
   156 			switch (event.type) {
   157 				case SDL_MOUSEBUTTONDOWN: {
   158 					SDL_Rect dst;
   159 
   160 					dst.x = event.button.x - bitmap->w/2;
   161 					dst.y = event.button.y - bitmap->h/2;
   162 					dst.w = bitmap->w;
   163 					dst.h = bitmap->h;
   164 					SDL_BlitSurface(bitmap, NULL,
   165 								screen, &dst);
   166 					SDL_UpdateRects(screen,1,&dst);
   167 					}
   168 					break;
   169 				case SDL_KEYDOWN:
   170 					/* Any key press quits the app... */
   171 					done = 1;
   172 					break;
   173 				case SDL_QUIT:
   174 					done = 1;
   175 					break;
   176 				default:
   177 					break;
   178 			}
   179 		}
   180 	}
   181 	SDL_FreeSurface(bitmap);
   182 	SDL_Quit();
   183 	return(0);
   184 }