xlib學習筆記-hello world

1. Install XLib

$sudo apt-get install libx11-dev

 

2.helloxlib.c
#include <X11/Xlib.h> #include <X11/Xutil.h> #include <X11/Xos.h> #include <X11/Xatom.h> #define DUMP_ERR printf int main() { Display *display; int screennum; int width; int height; const char *strdraw = "hello world"; Window win; GC gc; //打開顯示 沒有指明打開哪個顯示時使用環境變量中的DESPLAY display = XOpenDisplay(NULL); if( !display ){ DUMP_ERR("call XOpenDisplay(%s) fail/n", XDisplayName(NULL)); return 1; } //得到系統當前的屏幕 (如果使用虛擬屏幕的話 一般會有幾個) // get default screen screennum = DefaultScreen(display); //根據屏幕的大小決定窗口的大小 width = DisplayWidth(display,screennum)/4; height = DisplayHeight(display,screennum)/4; //創建窗口 // create window win = XCreateSimpleWindow(display, RootWindow(display,screennum), 0,0,width,height,3, BlackPixel(display,screennum), WhitePixel(display,screennum)); // 選擇窗口關心的事件 // select event XSelectInput(display,win, ExposureMask|KeyPressMask |ButtonPressMask|StructureNotifyMask); // 創建GC(圖形上下文) // create gc { unsigned long valuemask = 0; XGCValues values; gc = XCreateGC(display,win,valuemask,&values); } // 映射窗口 只有map後窗口纔會在屏幕上顯示 // show window XMapWindow(display,win); // 進入事件循環 // event loop while(1){ XEvent event; XNextEvent(display,&event); // 讀一個事件 switch(event.type){ case Expose: // expose window 顯示事件 if( event.xexpose.count != 0) break; XDrawString(display,win,gc,10,10, strdraw,strlen(strdraw)); break; // 按鍵事件 case ButtonPress: case KeyPress: XFreeGC(display,gc); //XCloseWindow(win); XCloseDisplay(display); return 0; default: break; } } }

 

Makefile
CC=gcc FLAGS=-Wall -lX11 RM=rm BIN=helloxlib SRC=helloxlib.c $(BIN):$(SRC) $(CC) $(FLAGS) -o $@ $^ clean: $(RM) $(BIN)