Xlib - 窗口未呈现

Question

I am creating library for Xlib (like gtk/qt, but simplified). And i don't see window at my desktop. GDB says nothing. What i must do to fix this bug? Already tried to move display declaration to main function. Used -g flag as compiling (to check with GDB). And no window! Seriously, it's awesome glitch!

FXL++ library:

#include <iostream>
#include <X11/Xlib.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h> 
using namespace std;

class fxlpp{
public:
    void init(){
        disp = XOpenDisplay(NULL);

        if(disp == NULL){ //error 1 if can't open display
            cerr << "Can't open display" << endl;
            exit(1);
        }

        screen = DefaultScreen(disp);
    }
    void mkWin(int winID, int x1, int y1, unsigned x2, unsigned y2){
        win[winID] = XCreateSimpleWindow(disp, RootWindow(disp, screen), x1, y1, x2, y2, 0, BlackPixel(disp, screen), WhitePixel(disp, screen));
        XSelectInput(disp, win[winID], ExposureMask | KeyPressMask);
        XMapWindow(disp, win[winID]);
    }
    void mkCWin(int cWinID, int pWinID, int x1, int y1, int x2, int y2){
        cWin[pWinID][cWinID] = XCreateSimpleWindow(disp, win[pWinID], x1, y1, x2, y2, 1, BlackPixel(disp, screen), WhitePixel(disp, screen));
        XSelectInput(disp, cWin[pWinID][cWinID], ExposureMask | KeyPressMask);
        XMapWindow(disp, cWin[pWinID][cWinID]);
    }

protected:
    Display *disp; //declare display pointer
    int screen; //declare display num integer
    Window win[129]; //declare window
    Window cWin[129][129]; //declare child win array
    XEvent event; //declare event handler
};

Code to test library:

#include <iostream>
#include "fxlpp.hpp"
using namespace std;

int main(){
    class fxlpp fxlpp;
    fxlpp.init();
    fxlpp.mkWin(1, 100, 100, 500, 300);
    sleep(2);
    return 0;
}

Answer 1

As I wrote before , there's a lot more to X11 than just create a window, paint some lines on it and expect output. You must setup the X event loop to receive events, handle at a minumum exposure events, but also keyboard, mouse, etc. in the proper way. So I'm afraid it's not a bug, it's a design flaw in your program.

For a short tutorial, see here .

Answer 2

尽管事件循环在大多数情况下都很重要，但在这种简单的情况下，您只需要在绘制后调用XFlush() 。