Hi! I solved the problem adding bitmap=NULL after somebody closes the windows or when the ESC buttom is pressed.
As you may have read, there was a log that worked, and that is rare, because one program give the same output for the same input; so, why some times did the program work? that smelled like pointer trouble.
So the program works fine now, thanks all for your help! 
1#include <stdio.h>
2#include <windows.h>
3/** CImg lib **/
4#include "CImg.h"
5using namespace cimg_library;
6
7/** Allegro lib**/
8#include <allegro5/allegro.h>
9#include <allegro5/allegro.h>
10#include <allegro5/allegro_audio.h>
11#include <allegro5/allegro_acodec.h>
12#include <allegro5/allegro_image.h>
13#include <allegro5/allegro_primitives.h>
14#include <allegro5/allegro_font.h>
15#include <allegro5/allegro_ttf.h>
16//#include <allegro_physfs.h>
17#include <allegro5/allegro_video.h>
18#include <allegro5/allegro_native_dialog.h>
19
20#define DEBUG
21
22void initialize();
23void shutdown();
24bool captura(int, int, int, int, char *);
25extern bool SaveBMPFile(char *, HBITMAP, HDC, int, int);
26inline int GetFilePointer(HANDLE FileHandle)
27{
28 return SetFilePointer(FileHandle, 0, 0, FILE_CURRENT);
29}
30
31int main(int argc, char** argv)
32{
33/** captura(0,0, 1366, 768,"pantalla3.bmp"); it takes a screenshot
34and save it, to show it later with allegro **/
35 initialize();
36 ALLEGRO_DISPLAY *display = al_create_display(500, 368);
37 ALLEGRO_VIDEO* video = NULL;
38 ALLEGRO_BITMAP* bitmap = NULL;
39// ALLEGRO_BITMAP* img = NULL;
40 ALLEGRO_EVENT_QUEUE *evqueue = al_create_event_queue();
41 ALLEGRO_TIMER *fps_timer = al_create_timer(1.0 / 60.0);
42 ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
43 chdir(al_path_cstr(path, '/'));
44 bool render = true, executing = true, redraw = true, playvideo1 = true;
45
46
47// al_set_display_flag(display, ALLEGRO_FULLSCREEN_WINDOW, true);
48// al_set_display_flag(display, ALLEGRO_PROGRAMMABLE_PIPELINE, true);
49
50 if (!display)
51 {
52 printf("Failed to create display!\n");
53 printf(" no displ ");
54 };
55 al_register_event_source(evqueue, al_get_keyboard_event_source());
56// al_register_event_source(evqueue, al_get_mouse_event_source());
57 al_register_event_source(evqueue, al_get_display_event_source(display));
58 al_register_event_source(evqueue, al_get_timer_event_source(fps_timer));
59
60 al_start_timer(fps_timer);
61 al_flip_display();
62 al_rest(1);
63 while (executing)
64 {
65 ALLEGRO_EVENT event;
66 al_wait_for_event(evqueue, &event);
67
68 switch (event.type)
69 {
70 case ALLEGRO_EVENT_TIMER:
71 render = true;
72 break;
73 case ALLEGRO_EVENT_DISPLAY_CLOSE:
74 executing = false;
75 bitmap=NULL; /** already added **/
76 break;
77
78 case ALLEGRO_EVENT_KEY_DOWN:
79 executing = event.keyboard.keycode != ALLEGRO_KEY_ESCAPE;
80 bitmap=NULL; /** already added **/
81 break;
82 }
83
84 if (render && al_is_event_queue_empty(evqueue))
85 {
86 render = false;
87
88 if(playvideo1==true)
89 {
90 video = al_open_video("welcome.ogv");
91 al_start_video(video, al_get_default_mixer());
92 playvideo1=false;
93 }
94 if(redraw)
95 {
96 al_clear_to_color(al_map_rgb(25,155,55));
97 redraw = false;
98 }
99 bitmap = al_get_video_frame(video);
100 if(bitmap==NULL)
101 printf(" bitmap empty ");
102 if(bitmap)
103 {
104 al_draw_bitmap(bitmap, 99, 100, 0);
105 al_flip_display();
106 al_rest(0.01);
107 }
108
109 }
110 render = false;
111 }
112
113 al_unregister_event_source(evqueue, al_get_keyboard_event_source());
114//al_unregister_event_source(evqueue, al_get_mouse_event_source());
115 al_unregister_event_source(evqueue, al_get_display_event_source(display));
116 al_unregister_event_source(evqueue, al_get_timer_event_source(fps_timer));
117//al_set_target_bitmap(NULL);
118 /** order changed, to avoid any trouble **/
119 al_destroy_path(path);
120 al_destroy_timer(fps_timer);
121 al_destroy_event_queue(evqueue);
122 al_destroy_bitmap(bitmap);
123 al_close_video(video);
124 al_destroy_display(display);
125
126
127 shutdown();
128
129 al_uninstall_system();
130//al_destroy_bitmap(img);
131
132 return 0;
133}
134
135void initialize()
136{
137 srand((unsigned int) time(NULL));
138
139#ifdef DEBUG
140 printf(" Allegro v%i.%i.%i\n",
141 al_get_allegro_version() >> 24,
142 (al_get_allegro_version() >> 16) & 255,
143 (al_get_allegro_version() >> 8) & 255);
144
145 printf("\n video v%i.%i.%i\n",
146 al_get_allegro_video_version() >> 24,
147 (al_get_allegro_video_version() >> 16) & 255,
148 (al_get_allegro_video_version() >> 8) & 255);
149#endif /* DEBUG */
150
151 if (!al_init())
152 {
153// al_show_native_message_box(display, "Error", "Error", "Fallo al inita5 !", NULL, ALLEGRO_MESSAGEBOX_ERROR);
154 printf("no carga init5");
155 exit(EXIT_FAILURE);
156 }
157 if (!al_install_audio())
158 {
159// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar audio!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
160 printf("no carga init5");
161 exit(EXIT_FAILURE);
162 }
163 if (!al_init_acodec_addon())
164 {
165// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar acodec addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
166 printf("no carga init5");
167 exit(EXIT_FAILURE);
168 }
169 if (!al_reserve_samples(1))
170 {
171// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar reserve samples!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
172 printf("no carga init5");
173 exit(EXIT_FAILURE);
174 }
175 if (!al_install_mouse())
176 {
177// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar mouse!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
178 printf("no carga init5");
179 exit(EXIT_FAILURE);
180 }
181 if (!al_install_keyboard())
182 {
183// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar teclado!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
184 printf("no carga init5");
185 exit(EXIT_FAILURE);
186 }
187 if (!al_init_video_addon())
188 {
189// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar vid addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
190 printf("no carga init5");
191 exit(EXIT_FAILURE);
192 }
193 if (!al_init_primitives_addon())
194 {
195// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar prim addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
196 printf("no carga init5");
197 exit(EXIT_FAILURE);
198 }
199 if (!al_init_font_addon())
200 {
201// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar font addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
202 printf("no carga init5");
203 exit(EXIT_FAILURE);
204 }
205 if (!al_init_ttf_addon())
206 {
207// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar ttf addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
208 printf("no carga init5");
209 exit(EXIT_FAILURE);
210 }
211 if (!al_init_image_addon())
212 {
213// al_show_native_message_box(display, "Error", "Error", "Fallo al inicializar img addon!", NULL, ALLEGRO_MESSAGEBOX_ERROR);
214 printf("no carga init5");
215 exit(EXIT_FAILURE);
216 }
217}
218
219void shutdown()
220{
221 al_shutdown_ttf_addon();
222 al_shutdown_font_addon();
223 al_shutdown_primitives_addon();
224 al_uninstall_keyboard();
225 al_uninstall_mouse();
226 al_uninstall_audio();
227}
228
229bool captura(int x, int y, int width, int height, char *filename)
230{
231// get a DC compat. w/ the screen
232 HDC hDc = CreateCompatibleDC(0);
233
234// make a bmp in memory to store the capture in
235 HBITMAP hBmp = CreateCompatibleBitmap(GetDC(0), width, height);
236
237// join em up
238 SelectObject(hDc, hBmp);
239
240// copy from the screen to my bitmap
241 BitBlt(hDc, 0, 0, width, height, GetDC(0), x, y, SRCCOPY);
242
243// save my bitmap
244 bool ret = SaveBMPFile(filename, hBmp, hDc, width, height);
245
246// free the bitmap memory
247 DeleteObject(hBmp);
248
249 return ret;
250}
251
252extern bool SaveBMPFile(char *filename, HBITMAP bitmap, HDC bitmapDC, int width, int height)
253{
254 bool Success=false;
255 HDC SurfDC=NULL; // GDI-compatible device context for the surface
256 HBITMAP OffscrBmp=NULL; // bitmap that is converted to a DIB
257 HDC OffscrDC=NULL; // offscreen DC that we can select OffscrBmp into
258 LPBITMAPINFO lpbi=NULL; // bitmap format info; used by GetDIBits
259 LPVOID lpvBits=NULL; // pointer to bitmap bits array
260 HANDLE BmpFile=INVALID_HANDLE_VALUE; // destination .bmp file
261 BITMAPFILEHEADER bmfh; // .bmp file header
262
263 // We need an HBITMAP to convert it to a DIB:
264 if ((OffscrBmp = CreateCompatibleBitmap(bitmapDC, width, height)) == NULL)
265 return false;
266
267 // The bitmap is empty, so let's copy the contents of the surface to it.
268 // For that we need to select it into a device context. We create one.
269 if ((OffscrDC = CreateCompatibleDC(bitmapDC)) == NULL)
270 return false;
271
272 // Select OffscrBmp into OffscrDC:
273 HBITMAP OldBmp = (HBITMAP)SelectObject(OffscrDC, OffscrBmp);
274
275 // Now we can copy the contents of the surface to the offscreen bitmap:
276 BitBlt(OffscrDC, 0, 0, width, height, bitmapDC, 0, 0, SRCCOPY);
277
278 // GetDIBits requires format info about the bitmap. We can have GetDIBits
279 // fill a structure with that info if we pass a NULL pointer for lpvBits:
280 // Reserve memory for bitmap info (BITMAPINFOHEADER + largest possible
281 // palette):
282 if ((lpbi = (LPBITMAPINFO)(new char[sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD)])) == NULL)
283 return false;
284
285
286 ZeroMemory(&lpbi->bmiHeader, sizeof(BITMAPINFOHEADER));
287 lpbi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
288 // Get info but first de-select OffscrBmp because GetDIBits requires it:
289 SelectObject(OffscrDC, OldBmp);
290 if (!GetDIBits(OffscrDC, OffscrBmp, 0, height, NULL, lpbi, DIB_RGB_COLORS))
291 return false;
292
293 // Reserve memory for bitmap bits:
294 if ((lpvBits = new char[lpbi->bmiHeader.biSizeImage]) == NULL)
295 return false;
296
297 // Have GetDIBits convert OffscrBmp to a DIB (device-independent bitmap):
298 if (!GetDIBits(OffscrDC, OffscrBmp, 0, height, lpvBits, lpbi, DIB_RGB_COLORS))
299 return false;
300
301 // Create a file to save the DIB to:
302 if ((BmpFile = CreateFile(filename,
303 GENERIC_WRITE,
304 0, NULL,
305 CREATE_ALWAYS,
306 FILE_ATTRIBUTE_NORMAL,
307 NULL)) == INVALID_HANDLE_VALUE)
308
309 return false;
310
311 DWORD Written; // number of bytes written by WriteFile
312
313 // Write a file header to the file:
314 bmfh.bfType = 19778; // 'BM'
315 // bmfh.bfSize = ??? // we'll write that later
316 bmfh.bfReserved1 = bmfh.bfReserved2 = 0;
317 // bmfh.bfOffBits = ??? // we'll write that later
318 if (!WriteFile(BmpFile, &bmfh, sizeof(bmfh), &Written, NULL))
319 return false;
320
321 if (Written < sizeof(bmfh))
322 return false;
323
324 // Write BITMAPINFOHEADER to the file:
325 if (!WriteFile(BmpFile, &lpbi->bmiHeader, sizeof(BITMAPINFOHEADER), &Written, NULL))
326 return false;
327
328 if (Written < sizeof(BITMAPINFOHEADER))
329 return false;
330
331 // Calculate size of palette:
332 int PalEntries;
333 // 16-bit or 32-bit bitmaps require bit masks:
334 if (lpbi->bmiHeader.biCompression == BI_BITFIELDS)
335 PalEntries = 3;
336 else
337 // bitmap is palettized?
338 PalEntries = (lpbi->bmiHeader.biBitCount <= 8) ?
339 // 2^biBitCount palette entries max.:
340 (int)(1 << lpbi->bmiHeader.biBitCount)
341 // bitmap is TrueColor -> no palette:
342 : 0;
343 // If biClrUsed use only biClrUsed palette entries:
344 if(lpbi->bmiHeader.biClrUsed)
345 PalEntries = lpbi->bmiHeader.biClrUsed;
346
347 // Write palette to the file:
348 if(PalEntries)
349 {
350 if (!WriteFile(BmpFile, &lpbi->bmiColors, PalEntries * sizeof(RGBQUAD), &Written, NULL))
351 return false;
352
353 if (Written < PalEntries * sizeof(RGBQUAD))
354 return false;
355 }
356
357 // The current position in the file (at the beginning of the bitmap bits)
358 // will be saved to the BITMAPFILEHEADER:
359 bmfh.bfOffBits = GetFilePointer(BmpFile);
360
361 // Write bitmap bits to the file:
362 if (!WriteFile(BmpFile, lpvBits, lpbi->bmiHeader.biSizeImage, &Written, NULL))
363 return false;
364
365 if (Written < lpbi->bmiHeader.biSizeImage)
366 return false;
367
368 // The current pos. in the file is the final file size and will be saved:
369 bmfh.bfSize = GetFilePointer(BmpFile);
370
371 // We have all the info for the file header. Save the updated version:
372 SetFilePointer(BmpFile, 0, 0, FILE_BEGIN);
373 if (!WriteFile(BmpFile, &bmfh, sizeof(bmfh), &Written, NULL))
374 return false;
375
376 if (Written < sizeof(bmfh))
377 return false;
378 delete[] lpvBits;
379 return true;
380}
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