1#include <allegro5/allegro.h>
2#include <allegro5/allegro_image.h>
3#include <allegro5/allegro_primitives.h>
4#include <allegro5/allegro_windows.h>
5#include <algorithm>
6#include <Windows.h>
7#define USER_EVENT_TYPE 999
8
9static int neww, newh
;
10ALLEGRO_EVENT_SOURCE user_event_source
;
11
12bool WinProcCallback
(ALLEGRO_DISPLAY* d, UINT msg, WPARAM wparam, LPARAM lparam, LRESULT
* result,
void* userdata
) {
13
14 if (msg
== WM_SIZING
) {
15
16 int oldh
= neww
;
17 int oldw
= newh
;
18
19 RECT r
= *(RECT
*)lparam
;
20 int rw
= (r.right
- r.left
) - 21;
21 int rh
= (r.bottom
- r.top
) - 42;
22
23 if (oldh
!= rh
|| oldw
!= rw
) {
24 ALLEGRO_EVENT ev
;
25 ev.user.data1
= rw
;
26 ev.user.data2
= rh
;
27 ev.type
= USER_EVENT_TYPE
;
28 neww
= rw
;
29 newh
= rh
;
30 al_emit_user_event(&user_event_source,
&ev,
0);
31 }
32
33 // Return true, so Allegro knows it doesn't need to do anything for this event.
34 return true;
35
36 }
37
38 // Return false, so Allegro will handle the event on its own.
39 return false;
40
41}
42
43int main
() {
44
45 // Initialize Allegro and required add-ons.
46 al_init();
47 al_init_primitives_addon();
48
49 // Set display flags and create the display.
50 al_set_new_display_flags(ALLEGRO_OPENGL
| ALLEGRO_RESIZABLE
);
51 ALLEGRO_DISPLAY* display
= al_create_display(640,
480);
52
53 // Create event queue and register event sources.
54 ALLEGRO_EVENT_QUEUE* event_queue
= al_create_event_queue();
55 al_register_event_source(event_queue,
al_get_display_event_source(display
));
56
57 ALLEGRO_TIMER* timer
= al_create_timer(1.
0f / 60.
0f);
58 al_register_event_source(event_queue,
al_get_timer_event_source(timer
));
59 al_start_timer(timer
);
60
61 al_init_user_event_source(&user_event_source
);
62 al_register_event_source(event_queue,
&user_event_source
);
63
64 // Set the background brush of the window.
65 HWND hwnd
= al_get_win_window_handle(display
);
66 HBRUSH brush
= CreateSolidBrush
(RGB(0,
0,
0));
67 SetClassLongPtr
(hwnd, GCLP_HBRBACKGROUND,
(LONG
)brush
);
68 DeleteObject
(brush
);
69
70 // Add callback function.
71 al_win_add_window_callback
(display, WinProcCallback,
0);
72
73 bool redraw
= false;
74 while (true) {
75
76 ALLEGRO_EVENT ev
;
77 al_wait_for_event(event_queue,
&ev
);
78
79 switch (ev.type
) {
80
81 case USER_EVENT_TYPE:
82 al_resize_display(display, ev.user.data1, ev.user.data2
);
83
84 case ALLEGRO_EVENT_DISPLAY_RESIZE:
85 al_acknowledge_resize(display
);
86 redraw
= true;
87 break;
88
89 case ALLEGRO_EVENT_TIMER:
90 redraw
= true;
91 break;
92
93 }
94
95 // Redraw the display contents.
96 if (redraw
&& al_is_event_queue_empty(event_queue
)) {
97
98 al_clear_to_color(al_map_rgb(0,
0,
0));
99 float w
= (std::min
)(al_get_display_width(display
),
al_get_display_height(display
));
100 float x
= al_get_display_width(display
) / 2.
0f - w
/ 2.
0f;
101 float y
= al_get_display_height(display
) / 2.
0f - w
/ 2.
0f;
102 al_draw_filled_rectangle(x, y, x
+ w, y
+ w,
al_map_rgb(192,
192,
192));
103 al_flip_display();
104
105 }
106
107 }
108
109 return 0;
110
111}