程式語言 - X Window (X11) - C/C++ - Load Font

參考資訊：
https://github.com/QMonkey/Xlib-demo
https://people.scs.carleton.ca/~claurend/Courses/COMP2401/Notes/COMP2401_Ch8_Graphics.pdf

main.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <X11/Xlib.h>
   
int main(int argc, char *argv[])
{
    GC gc = 0;
    Window win = 0;
    Display *display = NULL;
  
    display = XOpenDisplay(NULL);
    win = XCreateSimpleWindow(
        display,
        RootWindow(display, 0),
        0,
        0,
        320,
        240,
        0,
        0,
        0xffffff);
   
    XStoreName(display, win, "main");
    gc = XCreateGC(display, win, 0, NULL);
    XMapWindow(display, win);
    XFlush(display);
    usleep(100000);

    int x = 100;
    int y = 100;
    int ascent = 0;
    int descent = 0;
    int direction = 0;
    XFontStruct *font = NULL;
    XCharStruct overall = { 0 };
    const char *fontname = "-*-courier-*-*-*--32-*-*-*-*-*-*-*";
    font = XLoadQueryFont(display, fontname);
    if (!font) {
        font = XLoadQueryFont(display, "fixed");
    }
    XSetFont(display, gc, font->fid);
    XTextExtents(font, "TEST", 4, &direction, &ascent, &descent, &overall);
    XClearWindow(display, win);
    x = (320 - overall.width) / 2;
    y = 240 / 2 + (ascent - descent) / 2;
    XDrawString(display, win, gc, x, y, "TEST", 4);

    XFlush(display);
    usleep(3000000);
   
    XUnmapWindow(display, win);
    XDestroyWindow(display, win);
    XCloseDisplay(display);
   
    return 0;
}

編譯、測試

$ gcc main.c -o main -lX11
$ ./main