XLib是X Window编程的基础Library, 使用时首先需要在文件头中

#include <X11/Xlib.h>

在绘制图形界面之前, 第一步要连接到一个Display. 就好比画画之前先要找到一张桌子或者画板, 你不能举着一张纸直接就往上泼墨...

// Open display 
Display* display; 
display = XOpenDisplay(""); 
if(!display){ 
    printf("Cannot open display\n"); 
    exit(-1); 
} 

之后可以通过一些函数, 获取当前Display的各种信息. 如需要, 可以保存到variable里供后边绘图时候使用.

int printScreenInfo(Display* display){ 
    int screen_num;  // 当前屏幕的编号 
    int screen_width;    // 当前屏幕的宽度 
    int screen_height;   // 当前屏幕的高度 
    Window root_window; // root窗口的编号 
    unsigned long white_pixel;   // 白色像素的编号 
    unsigned long black_pixel;   // 黑色像素的编号 
    screen_num = DefaultScreen(display); 
    screen_width = DisplayWidth(display, screen_num); 
    screen_height = DisplayHeight(display, screen_num); 
    root_window = RootWindow(display, screen_num); 
    white_pixel = WhitePixel(display, screen_num); 
    black_pixel = BlackPixel(display, screen_num); 
    printf("Screen Number: \t%d\n
                    Width: \t%d\n
                   Height: \t%d\n
                     Root: \t%d\n
                    White: \t%d\n
                    Black: \t%d\n", 
           screen_num, screen_width, screen_height, 
           root_window, white_pixel, black_pixel); 
    return 0; 
}

画板摆好以后, 就要在上边铺上一张用来画画的纸, 也就是一个窗口...

// Define window properties 
Window window; 
int x, y; 
unsigned int width, height, border_width; 
width = 850; 
height = 470; 
x = y = 50; 
border_width = 0; 

// Define display constants 
int screen_num = DefaultScreen(display); 
unsigned long white_pixel = WhitePixel(display, screen_num); 
unsigned long black_pixel = BlackPixel(display, screen_num); 

// Create window 
window = XCreateSimpleWindow(display, RootWindow(display, screen_num), 
                             x, y, width, height, border_width, 
                             black_pixel, white_pixel); 

// Map win to display & Flush display 
XMapWindow(display, win); 
XFlush(display);

万事俱备只欠画画儿了`XLib的function都挺容易看懂的...

int drawInterface(Display* display, Window window, unsigned long black_pixel, unsigned long white_pixel ){
    // Define GCs for drawing 
    GC foregc; 
    foregc = XCreateGC (display, window, 0, 0); 
    XSetBackground( display, foregc, black_pixel ); 
    XSetForeground( display, foregc, white_pixel ); 

    // Start Drawing 
    XClearWindow(display, window); 
    // Door 
    XDrawRectangle(display, window, foregc, 1, 1, 630, 460); 
    XFillRectangle(display, window, foregc, 66, 66, 480, 330); 
    // Dashboard 
    XDrawRectangle(display, window, foregc, 633, 1, 215, 460); 
    XDrawRectangle(display, window, foregc, 650, 45, 185, 330); 
    // Timer 
    XDrawRectangle(display, window, foregc, 660, 60, 160, 65); 
    // And More... 

    // Flush display to show everything changed 
    XFlush(display);
}

Event Handling的部分晚点再整理