使用XCB编写X Window程序（04）：在窗口中绘制文字

 1 #include <stdlib.h>
 2 #include <stdio.h>
 3 #include <string.h>
 4 #include <inttypes.h>
 5 #include <xcb/xcb.h>
 6 
 7 
 8 #define    WIDTH 600
 9 #define    HEIGHT 400
10 #define TEST_COOKIE(fn,errMessage) 11     cookie=fn; 12     error=xcb_request_check(connection,cookie); 13     if(error){ 14         fprintf(stderr, "Error: %s : %"PRIu8"\n", errMessage, error->error_code); 15     } 16 
17 static void drawText(xcb_connection_t *connection, xcb_screen_t *screen, xcb_window_t window,
18         int16_t x, int16_t y, const char *font_name, const char *string){
19     /*cookie and error, for TEST_COOKIE */
20     xcb_void_cookie_t cookie;
21     xcb_generic_error_t *error;
22 
23     xcb_font_t font = xcb_generate_id(connection);
24     TEST_COOKIE(xcb_open_font_checked(connection, font, strlen(font_name), font_name), "Can‘t open font");
25     xcb_gcontext_t gc = xcb_generate_id(connection);
26     uint32_t mask = XCB_GC_FOREGROUND | XCB_GC_BACKGROUND | XCB_GC_FONT;
27     uint32_t values[3] = {screen->black_pixel, screen->white_pixel, font};
28     TEST_COOKIE(xcb_create_gc_checked(connection, gc, window, mask, values), "Can‘t create GC")
29     /*draw the text*/
30     TEST_COOKIE(xcb_image_text_8_checked(connection, strlen(string), window, gc, x, y, string), "Can‘t draw text");
31     /*close the font*/
32     xcb_close_font(connection, font);
33     xcb_free_gc(connection, gc);
34 }
35 
36 int main()
37 {
38     xcb_connection_t *connection = xcb_connect(NULL, NULL);
39     xcb_screen_t *screen = xcb_setup_roots_iterator( xcb_get_setup(connection)).data;
40 
41     /*Create the window*/
42     xcb_window_t window = xcb_generate_id(connection);
43     uint32_t mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
44     uint32_t values[2];
45     values[0] = screen->white_pixel;
46     values[1] = XCB_EVENT_MASK_KEY_RELEASE | XCB_EVENT_MASK_BUTTON_PRESS |
47         XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_POINTER_MOTION;
48     xcb_create_window(connection, screen->root_depth,
49             window, screen->root, 20, 200,
50             WIDTH, HEIGHT,
51             0, XCB_WINDOW_CLASS_INPUT_OUTPUT,
52             screen->root_visual,
53             mask, values);
54     xcb_map_window(connection, window);
55     xcb_flush(connection);
56 
57     /*event loop*/
58     xcb_generic_event_t *event;
59     while((event = xcb_wait_for_event(connection))){
60         switch(event->response_type & ~0x80){
61             case XCB_EXPOSE:
62                 {
63                     drawText(connection, screen, window, 10, 20,"fixed", "Press ESC key to exit.");
64                     drawText(connection, screen, window, 10, 40, "Dejavu Sans Mono", "Press ESC key to exit.");
65                     drawText(connection, screen, window, 10, 60, "文泉驿正黑", "按ESC键退出。");
66                     break;
67                 }
68             case XCB_KEY_RELEASE:
69                 {
70                     xcb_key_release_event_t *kr = (xcb_key_release_event_t*)event;
71                     switch(kr->detail){
72                         case 9: /* ESC */
73                             {
74                                 free(event);
75                                 xcb_disconnect(connection);
76                                 return 0;
77                             }
78                     }
79                 }
80         }
81         free(event);
82     }
83     return 0;
84 }

int error;
error = some_function(...);
if(error){
    printf("...some message...");
    ...
}
error = another_function(...);
if(error){
    printf("....another message...");
    ...
}