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我試圖用Xlib，XF86VidMode和OpenGL編寫一些簡單的圖形。我有兩個問題：使用xcb和randr獲取屏幕信息
- 的Xlib似乎並不具有WM_TIMER相當於，所以我寫了發送郵件到解鎖消息循環的SIGALRM的處理程序，但由於這種用法是完全線程安全的，程序稍後會掛起。因此我嘗試在xcb中重新編碼。
- XF86VidMode很難使用，我不喜歡結果，所以我切換到RandR。
完成上述事情後，事實證明xcb具有相同的掛起，所以我無法編碼阻止消息循環。相反，我每隔一段時間就會進行一次輪詢，程序沒有掛起，但是有些跳幀令人討厭。
雖然我可以使用RandR切換視頻模式，但我想使用xcb版本，但這種模式無效。我剽竊了xcb的一個@datenwolf的例子，但不知何故xcb_randr_get_screen_info_reply不起作用。它應該返回一個指向結構的指針，後面跟着一組屏幕尺寸（mm中的尺寸錯誤），然後是刷新率數據。刷新率數據是垃圾並且大部分爲零。我究竟做錯了什麼？
/*
gcc rrxcb.c -lxcb-randr -lxcb -lX11 -lX11-xcb -lGL -orrxcb
*/
#include <xcb/randr.h>
#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xlib-xcb.h>
#include <xcb/xcb.h>
#include <GL/glx.h>
#include <unistd.h>
void screen_from_Xlib_Display(
Display * const display,
xcb_connection_t *connection,
int * const out_screen_num,
xcb_screen_t ** const out_screen)
{
xcb_screen_iterator_t screen_iter = xcb_setup_roots_iterator(xcb_get_setup(connection));
int screen_num = DefaultScreen(display);
while(screen_iter.rem && screen_num > 0) {
xcb_screen_next(&screen_iter);
--screen_num;
}
*out_screen_num = screen_num;
*out_screen = screen_iter.data;
}
int main()
{
Display *display;
xcb_connection_t *connection;
xcb_window_t win;
const int GLX_TRUE = True;
int attrib_list[] = {GLX_X_RENDERABLE,GLX_TRUE,
GLX_DRAWABLE_TYPE,GLX_WINDOW_BIT,
GLX_RENDER_TYPE,GLX_RGBA_BIT,
GLX_CONFIG_CAVEAT,GLX_NONE,
GLX_DOUBLEBUFFER,GLX_TRUE,
GLX_BUFFER_SIZE,32,
GLX_DEPTH_SIZE,24,
GLX_STENCIL_SIZE,8,
0};
GLXFBConfig *FBConfigs;
int nelements;
GLXFBConfig fb_config;
XVisualInfo *visual;
int visualID;
GLXContext context;
xcb_colormap_t colormap;
xcb_void_cookie_t create_color;
xcb_void_cookie_t create_win;
const uint32_t eventmask = XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS;
const uint32_t valuemask = XCB_CW_EVENT_MASK | XCB_CW_COLORMAP;
uint32_t valuelist[] = {eventmask,colormap};
xcb_randr_get_screen_info_cookie_t screen_info;
xcb_randr_get_screen_info_reply_t *reply;
int screen_num;
xcb_screen_t *screen;
xcb_generic_error_t *error;
xcb_randr_screen_size_t *sizes;
int sizes_length;
xcb_randr_refresh_rates_iterator_t rates_iter;
uint16_t *rates;
int rates_length;
int i;
/* Open Xlib Display */
display = XOpenDisplay(NULL);
printf("display = %p\n",display);
connection = XGetXCBConnection(display);
printf("connection = %p\n",connection);
XSetEventQueueOwner(display,XCBOwnsEventQueue);
win = xcb_generate_id(connection);
printf("win = %d\n",win);
screen_from_Xlib_Display(display,connection,&screen_num,&screen);
printf("screen_num = %d\n",screen_num);
printf("screen->root = %d\n",screen->root);
FBConfigs = glXChooseFBConfig(display,screen_num,attrib_list,
&nelements);
printf("FBConfig = %p\n",FBConfigs);
printf("nelements = %d\n",nelements);
fb_config = FBConfigs[0];
visual = glXGetVisualFromFBConfig(display,fb_config);
printf("visual = %p\n",visual);
visualID = visual->visualid;
printf("visualID = %d\n",visualID);
context = glXCreateNewContext(display,fb_config,GLX_RGBA_TYPE,
0,True);
printf("context = %p\n",context);
colormap = xcb_generate_id(connection);
printf("colormap = %d\n",colormap);
create_color = xcb_create_colormap_checked(connection,
XCB_COLORMAP_ALLOC_NONE,colormap,screen->root,visualID);
printf("create_color.sequence = %d\n",create_color.sequence);
error = xcb_request_check(connection,create_color);
printf("error = %p\n",error);
create_win = xcb_create_window_checked(connection,
XCB_COPY_FROM_PARENT,win, screen->root,0,0,640,480,2,
XCB_WINDOW_CLASS_INPUT_OUTPUT,visualID,valuemask,valuelist);
printf("create_win.sequence = %d\n",create_win.sequence);
error = xcb_request_check(connection,create_win);
printf("error = %p\n",error);
screen_info = xcb_randr_get_screen_info_unchecked(connection, screen->root);
printf("screen_info.sequence = %d\n",screen_info.sequence);
reply = xcb_randr_get_screen_info_reply(connection,screen_info,
NULL);
printf("reply = %p\n",reply);
printf("reply->response_type = %d\n",reply->response_type);
printf("reply->rotations = %d\n",reply->rotations);
printf("reply->sequence = %d\n",reply->sequence);
printf("reply->length = %d\n",reply->length);
printf("reply->nSizes = %d\n",reply->nSizes);
printf("reply->sizeID = %d\n",reply->sizeID);
printf("reply->rotation = %d\n",reply->rotation);
printf("reply->rate = %d\n",reply->rate);
printf("reply->nInfo = %d\n",reply->nInfo);
printf("reply+1 = %p\n",reply+1);
sizes = xcb_randr_get_screen_info_sizes(reply);
printf("sizes = %p\n",sizes);
sizes_length = xcb_randr_get_screen_info_sizes_length(reply);
printf("sizes_length = %d\n",sizes_length);
rates_iter = xcb_randr_get_screen_info_rates_iterator(reply);
printf("rates_iter.data = %p\n",rates_iter.data);
printf("rates_iter.rem = %d\n",rates_iter.rem);
printf("rates_iter.index = %d\n",rates_iter.index);
for(; rates_iter.rem; xcb_randr_refresh_rates_next(&rates_iter))
{
rates = xcb_randr_refresh_rates_rates(rates_iter.data);
printf("rates = %p\n",rates);
rates_length =
xcb_randr_refresh_rates_rates_length(rates_iter.data);
printf("rates_length = %d\n",rates_length);
printf("rates[0] = %d\n",rates[0]);
/*
for(i = 0; i < rates_length; i++)
{
printf("%d%c",rates[i],(i==rates_length-1)?'\n':' ');
}
*/
}
for(i = 0; i < sizes_length; i++)
{
printf("%d %d %d %d %d\n",i,sizes[i].width,sizes[i].height,sizes[i].mwidth,sizes[i].mheight);
}
return 0;
}
所以我的輸出是
display = 0x563687942010
connection = 0x563687943410
win = 54525954
screen_num = 0
screen->root = 241
FBConfig = 0x563687951b20
nelements = 8
visual = 0x563687951d30
visualID = 33
context = 0x563687951680
colormap = 54525956
create_color.sequence = 26
error = (nil)
create_win.sequence = 28
error = (nil)
screen_info.sequence = 31
reply = 0x563687abde30
reply->response_type = 1
reply->rotations = 63
reply->sequence = 31
reply->length = 36
reply->nSizes = 18
reply->sizeID = 1
reply->rotation = 1
reply->rate = 30
reply->nInfo = 53
reply+1 = 0x563687abde50
sizes = 0x563687abde50
sizes_length = 18
rates_iter.data = 0x563687abdee0
rates_iter.rem = 35
rates_iter.index = 176
rates = 0x563687abdee2
rates_length = 0
rates[0] = 0
rates = 0x563687abdee4
rates_length = 0
rates[0] = 0
rates = 0x563687abdee6
rates_length = 0
...
rates = 0x563687add7a8
rates_length = 0
rates[0] = 0
0 4096 2160 1872 1053
1 3840 2160 1872 1053
2 1920 1080 1872 1053
3 1680 1050 1872 1053
4 1600 900 1872 1053
5 1280 1024 1872 1053
6 1440 900 1872 1053
7 1366 768 1872 1053
8 1280 800 1872 1053
9 1152 864 1872 1053
10 1280 720 1872 1053
11 1024 768 1872 1053
12 832 624 1872 1053
13 800 600 1872 1053
14 720 576 1872 1053
15 720 480 1872 1053
16 640 480 1872 1053
17 720 400 1872 1053
任何人都可以發現什麼，我做錯了什麼？