1#include<X11/Xlib.h>
  2#include<X11/keysym.h>
  3
  4#include<stdbool.h>
  5#include<stdio.h>
  6#include<stdlib.h>
  7
  8int main(int ac, char **av)
  9{
 10	int wi=640, hi=480;
 11
 12	Display *d=XOpenDisplay(NULL);
 13	if(!d)
 14	{
 15		fprintf(stderr, "couldnt open display\n");
 16		return 1;
 17	}
 18
 19	int s=DefaultScreen(d);
 20
 21	XColor bg;
 22	XParseColor(d, DefaultColormap(d, s), av[1] ? av[1] : "#ffffff", &bg);
 23	XAllocColor(d, DefaultColormap(d, s), &bg);
 24
 25	Window w=XCreateSimpleWindow(d, RootWindow(d, s),
 26			100, 100, wi, hi, 0, BlackPixel(d,s), 
 27			WhitePixel(d, s));
 28	XStoreName(d, w, "xd");
 29	XSelectInput(d, w, ExposureMask|KeyPressMask|StructureNotifyMask|
 30			ButtonPressMask|ButtonReleaseMask|
 31			PointerMotionMask);
 32	XMapWindow(d, w);
 33	GC gc=XCreateGC(d, w, 0, NULL);
 34	Pixmap p=XCreatePixmap(d,w,wi,hi,DefaultDepth(d,s));
 35	XSetForeground(d, gc, bg.pixel);
 36	XFillRectangle(d, p,gc,0,0,wi,hi);
 37	XSetForeground(d, gc, BlackPixel(d,s));
 38
 39	int z=20;
 40	XSetLineAttributes(d, gc, z, LineSolid, CapRound, JoinRound);
 41
 42	bool dr=false, er=false;
 43	int lx=0, ly=0;
 44
 45	while(1)
 46	{
 47		XEvent ev;
 48		XNextEvent(d, &ev);
 49		XSetLineAttributes(d, gc, z, LineSolid, CapRound, JoinRound);
 50
 51		switch(ev.type)
 52		{
 53			case Expose:
 54				XCopyArea(d,p,w,gc,0,0,wi,hi,0,0);
 55				break;
 56			case ConfigureNotify:
 57				if(ev.xconfigure.width>wi&&ev.xconfigure.height>hi)
 58				{
 59					Pixmap l=XCreatePixmap(d,w,
 60							ev.xconfigure.width,ev.xconfigure.height,
 61							DefaultDepth(d,s));
 62
 63					XSetForeground(d, gc, bg.pixel);
 64					XFillRectangle(d, l,gc,0,0,ev.xconfigure.width,ev.xconfigure.height);
 65
 66					int cw = wi < ev.xconfigure.width ? wi : ev.xconfigure.width;
 67					int ch = hi < ev.xconfigure.height ? hi : ev.xconfigure.height;
 68
 69					XCopyArea(d,p,l,gc,0,0,
 70							cw,ch,
 71							0,0);
 72					XFreePixmap(d,p);
 73					p=l;
 74
 75					wi=ev.xconfigure.width;
 76					hi=ev.xconfigure.height;
 77
 78					XCopyArea(d,p,w,gc,0,0,wi,hi,0,0);
 79				}
 80				break;
 81			case ButtonPress:
 82				if(ev.xbutton.button==Button1)
 83				{
 84					dr=true;
 85					lx=ev.xbutton.x;
 86					ly=ev.xbutton.y;
 87				}
 88				break;
 89			case ButtonRelease:
 90				if(ev.xbutton.button==Button1)
 91				{
 92					dr=false;
 93				}
 94				break;
 95			case MotionNotify:
 96				if (dr)
 97				{
 98					XSetForeground(d, gc, er ? bg.pixel : BlackPixel(d,s));
 99					XDrawLine(d,p,gc,lx,ly,
100							ev.xmotion.x,
101							ev.xmotion.y);
102					XCopyArea(d,p,w,gc,0,0,wi,hi,0,0);
103					lx=ev.xmotion.x;
104					ly=ev.xmotion.y;
105				}
106				break;
107			case KeyPress: {
108				KeySym k=XLookupKeysym(&ev.xkey, 0);
109				if (k==XK_q||k==XK_Escape) goto q;
110				if (k==XK_c) {
111					XSetForeground(d, gc, bg.pixel);
112					XFillRectangle(d, p,gc,0,0,wi,hi);
113					XCopyArea(d,p,w,gc,0,0,wi,hi,0,0);
114					XSetForeground(d, gc, BlackPixel(d,s));
115				}
116				if (k==XK_e) {
117					er=!er;
118					printf("er=%s\n", er ? "true" : "false");
119				}
120
121
122				if (k==XK_i) z= z<=1 ? z+4 : z+5;
123				if (k==XK_o) z= z>6  ? (z-5) : 1;
124				if (k==XK_p) z=20;
125
126				if (k==XK_i||k==XK_o||k==XK_p) printf("z=%d\n", z);
127
128				break;
129			}
130		}
131	}
132
133q:
134	XFreePixmap(d,p);
135	XFreeGC(d,gc);
136	XDestroyWindow(d,w);
137	XCloseDisplay(d);
138	return 0;
139
140}
141