SDL Guide 中文译版(四)

  1<stdio.h>
  2    #include <stdlib.h>
  3    #include "SDL.h"
  4    #include "SDL_timer.h"
  5    
  6    void ComplainAndExit(void)
  7    {
  8        fprintf(stderr, "Problem: %s\n", SDL_GetError());
  9        exit(1);
 10    }
 11    
 12    int main(int argc, char *argv[])
 13    {
 14        SDL_PixelFormat fmt;
 15        SDL_Surface *screen, *locked;
 16        SDL_Surface *imagebmp, *image;
 17        SDL_Rect dstrect;
 18        int i;
 19        Uint8 *buffer;
 20    
 21        /* Initialize SDL */
 22        if ( SDL_Init(SDL_INIT_VIDEO) &lt; 0 ) {
 23            ComplainAndExit();
 24        }
 25        atexit(SDL_Quit);
 26    
 27        /* Load a BMP image into a surface */
 28        imagebmp = SDL_LoadBMP("image.bmp");
 29        if ( imagebmp == NULL ) {
 30            ComplainAndExit();
 31        }
 32    
 33        /* Set the video mode (640x480 at native depth) */
 34        screen = SDL_SetVideoMode(640, 480, 0, SDL_HWSURFACE|SDL_FULLSCREEN);
 35        if ( screen == NULL ) {
 36            ComplainAndExit();
 37        }
 38    
 39        /* Set the video colormap */
 40        if ( imagebmp-&gt;format-&gt;palette != NULL ) {
 41            SDL_SetColors(screen,
 42                          imagebmp-&gt;format-&gt;palette-&gt;colors, 0,
 43                          imagebmp-&gt;format-&gt;palette-&gt;ncolors);
 44        }
 45    
 46        /* Convert the image to the video format (maps colors) */
 47        image = SDL_DisplayFormat(imagebmp);
 48        SDL_FreeSurface(imagebmp);
 49        if ( image == NULL ) {
 50            ComplainAndExit();
 51        }
 52    
 53        /* Draw bands of color on the raw surface */
 54        if ( SDL_MUSTLOCK(screen) ) {
 55            if ( SDL_LockSurface(screen) &lt; 0 )
 56                ComplainAndExit();
 57        }
 58        buffer=(Uint8 *)screen-&gt;pixels;
 59        for ( i=0; ih; ++i ) {
 60            memset(buffer,(i*255)/screen-&gt;h,
 61                   screen-&gt;w*screen-&gt;format-&gt;BytesPerPixel);
 62                   buffer += screen-&gt;pitch;
 63        }
 64        if ( SDL_MUSTLOCK(screen) ) {
 65            SDL_UnlockSurface(screen);
 66        }
 67    
 68        /* Blit the image to the center of the screen */
 69        dstrect.x = (screen-&gt;w-image-&gt;w)/2;
 70        dstrect.y = (screen-&gt;h-image-&gt;h)/2;
 71        dstrect.w = image-&gt;w;
 72        dstrect.h = image-&gt;h;
 73        if ( SDL_BlitSurface(image, NULL, screen, &amp;dstrect) &lt; 0 ) {
 74            SDL_FreeSurface(image);
 75            ComplainAndExit();
 76        }
 77        SDL_FreeSurface(image);
 78    
 79        /* Update the screen */
 80        SDL_UpdateRects(screen, 1, &amp;dstrect);
 81    
 82        SDL_Delay(5000);        /* Wait 5 seconds */
 83        exit(0);
 84    }
 85    
 86
 87###  过滤和处理事件 
 88    
 89    
 90    #include <stdio.h>
 91    #include <stdlib.h>
 92    
 93    #include "SDL.h"
 94    
 95    /* This function may run in a separate event thread */
 96    int FilterEvents(const SDL_Event *event) {
 97        static int boycott = 1;
 98    
 99        /* This quit event signals the closing of the window */
100        if ( (event-&gt;type == SDL_QUIT) &amp;&amp; boycott ) {
101            printf("Quit event filtered out -- try again.\n");
102            boycott = 0;
103            return(0);
104        }
105        if ( event-&gt;type == SDL_MOUSEMOTION ) {
106            printf("Mouse moved to (%d,%d)\n",
107                    event-&gt;motion.x, event-&gt;motion.y);
108            return(0);    /* Drop it, we've handled it */
109        }
110        return(1);
111    }
112    
113    int main(int argc, char *argv[])
114    {
115        SDL_Event event;
116    
117        /* Initialize the SDL library (starts the event loop) */
118        if ( SDL_Init(SDL_INIT_VIDEO) &lt; 0 ) {
119            fprintf(stderr,
120                    "Couldn't initialize SDL: %s\n", SDL_GetError());
121            exit(1);
122        }
123    
124        /* Clean up on exit, exit on window close and interrupt */
125        atexit(SDL_Quit);
126    
127        /* Ignore key events */
128        SDL_EventState(SDL_KEYDOWN, SDL_IGNORE);
129        SDL_EventState(SDL_KEYUP, SDL_IGNORE);
130    
131        /* Filter quit and mouse motion events */
132        SDL_SetEventFilter(FilterEvents);
133    
134        /* The mouse isn't much use unless we have a display for reference */
135        if ( SDL_SetVideoMode(640, 480, 8, 0) == NULL ) {
136            fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n",
137                            SDL_GetError());
138            exit(1);
139        }
140    
141        /* Loop waiting for ESC+Mouse_Button */
142        while ( SDL_WaitEvent(&amp;event) &gt;= 0 ) {
143            switch (event.type) {
144                case SDL_ACTIVEEVENT: {
145                    if ( event.active.state &amp; SDL_APPACTIVE ) {
146                        if ( event.active.gain ) {
147                            printf("App activated\n");
148                        } else {
149                            printf("App iconified\n");
150                        }
151                    }
152                }
153                break;
154                        
155                case SDL_MOUSEBUTTONDOWN: {
156                    Uint8 *keys;
157    
158                    keys = SDL_GetKeyState(NULL);
159                    if ( keys[SDLK_ESCAPE] == SDL_PRESSED ) {
160                        printf("Bye bye...\n");
161                        exit(0);
162                    }
163                    printf("Mouse button pressed\n");
164                }
165                break;
166    
167                case SDL_QUIT: {
168                    printf("Quit requested, quitting.\n");
169                    exit(0);
170                }
171                break;
172            }
173        }
174        /* This should never happen */
175        printf("SDL_WaitEvent error: %s\n", SDL_GetError());
176        exit(1);
177    }
178    
179
180###  打开音频设备 
181    
182    
183        SDL_AudioSpec wanted;
184        extern void fill_audio(void *udata, Uint8 *stream, int len);
185    
186        /* Set the audio format */
187        wanted.freq = 22050;
188        wanted.format = AUDIO_S16;
189        wanted.channels = 2;    /* 1 = mono, 2 = stereo */
190        wanted.samples = 1024;  /* Good low-latency value for callback */
191        wanted.callback = fill_audio;
192        wanted.userdata = NULL;
193    
194        /* Open the audio device, forcing the desired format */
195        if ( SDL_OpenAudio(&amp;wanted, NULL) &lt; 0 ) {
196            fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
197            return(-1);
198        }
199        return(0);
200    
201
202###  播放音频 
203    
204    
205        static Uint8 *audio_chunk;
206        static Uint32 audio_len;
207        static Uint8 *audio_pos;
208    
209        /* The audio function callback takes the following parameters:
210           stream:  A pointer to the audio buffer to be filled
211           len:     The length (in bytes) of the audio buffer
212        */
213        void fill_audio(void *udata, Uint8 *stream, int len)
214        {
215            /* Only play if we have data left */
216            if ( audio_len == 0 )
217                return;
218    
219            /* Mix as much data as possible */
220            len = ( len &gt; audio_len ? audio_len : len );
221            SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME)
222            audio_pos += len;
223            audio_len -= len;
224        }
225    
226        /* Load the audio data ... */
227    
228        ;;;;;
229    
230        audio_pos = audio_chunk;
231    
232        /* Let the callback function play the audio chunk */
233        SDL_PauseAudio(0);
234    
235        /* Do some processing */
236    
237        ;;;;;
238    
239        /* Wait for sound to complete */
240        while ( audio_len &gt; 0 ) {
241            SDL_Delay(100);         /* Sleep 1/10 second */
242        }
243        SDL_CloseAudio();
244    
245
246###  列出所有CDROM 
247    
248    
249        #include "SDL.h"
250    
251        /* Initialize SDL first */
252        if ( SDL_Init(SDL_INIT_CDROM) &lt; 0 ) {
253            fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
254            exit(1);
255        }
256        atexit(SDL_Quit);
257    
258        /* Find out how many CD-ROM drives are connected to the system */
259        printf("Drives available: %d\n", SDL_CDNumDrives());
260        for ( i=0; i<sdl_cdnumdrives(); "couldn't="" ###="" %d:="" %s\n",="" (="" (status)="" )="" *cdrom;="" *status_str;="" ++i="" ;="" \"%s\"\n",="" break;="" case="" cd-rom="" cd_error:="" cd_paused:="" cd_playing:="" cd_stopped:="" cd_trayempty:="" cdrom="NULL" cdstatus="" char="" default="" drive:="" exit(2);="" fprintf(stderr,="" i,="" if="" open="" printf("drive="" sdl_cd="" sdl_cdname(i));="" sdl_geterror());="" status="" status:="" status;="" status_str="error state" status_str);="" switch="" {="" }="" 打开缺省cdrom驱动器="">= CD_PLAYING ) {
261            int m, s, f;
262            FRAMES_TO_MSF(cdrom-&gt;cur_frame, &amp;m, &amp;s, &amp;f);
263            printf("Currently playing track %d, %d:%2.2d\n",
264            cdrom-&gt;track[cdrom-&gt;cur_track].id, m, s);
265        }
266    
267
268###  列出CD上所有音轨 
269    
270    
271        SDL_CD *cdrom;          /* Assuming this has already been set.. */
272        int i;
273        int m, s, f;
274    
275        SDL_CDStatus(cdrom);
276        printf("Drive tracks: %d\n", cdrom-&gt;numtracks);
277        for ( i=0; i<cdrom->numtracks; ++i ) {
278            FRAMES_TO_MSF(cdrom-&gt;track[i].length, &amp;m, &amp;s, &amp;f);
279            if ( f &gt; 0 )
280                ++s;
281            printf("\tTrack (index %d) %d: %d:%2.2d\n", i,
282            cdrom-&gt;track[i].id, m, s);
283        }
284    
285
286###  播放CD 
287    
288    
289        SDL_CD *cdrom;          /* Assuming this has already been set.. */
290    
291        // Play entire CD:
292        if ( CD_INDRIVE(SDL_CDStatus(cdrom)) )
293            SDL_CDPlayTracks(cdrom, 0, 0, 0, 0);
294    
295            // Play last track:
296            if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) {
297                SDL_CDPlayTracks(cdrom, cdrom-&gt;numtracks-1, 0, 0, 0);
298            }
299    
300            // Play first and second track and 10 seconds of third track:
301            if ( CD_INDRIVE(SDL_CDStatus(cdrom)) )
302                SDL_CDPlayTracks(cdrom, 0, 0, 2, 10);
303    
304
305###  基于时间的游戏主循环 
306    
307    
308    #define TICK_INTERVAL    30
309    
310    Uint32 TimeLeft(void)
311    {
312        static Uint32 next_time = 0;
313        Uint32 now;
314    
315        now = SDL_GetTicks();
316        if ( next_time &lt;= now ) {
317            next_time = now+TICK_INTERVAL;
318            return(0);
319        }
320        return(next_time-now);
321    }
322    
323    
324    /* main game loop
325    
326        while ( game_running ) {
327            UpdateGameState();
328            SDL_Delay(TimeLeft());
329        }</cdrom-></sdl_cdnumdrives();></stdlib.h></stdio.h></stdlib.h></stdio.h>