TINYWM

我现在用的wm是dwm, 它是linux的一个极简的窗口管理器。基于C语言，大概只有2000行的代码。不过它还不是最简单的窗口管理器。最简单的窗口管理器是tinywm: http://incise.org/tinywm.html。源码如下，我稍微整理一下格式：

/* TinyWM is written by Nick Welch <mack@incise.org>, 2005.
 *
 * This software is in the public domain
 * and is provided AS IS, with NO WARRANTY. */

#include <X11/Xlib.h>

#define MAX(a, b) ((a) > (b) ? (a) : (b))

int main()
{
    Display * dpy;
    Window root;
    XWindowAttributes attr;
    XButtonEvent start;
    XEvent ev;

    if(!(dpy = XOpenDisplay(0x0))) return 1;

    root = DefaultRootWindow(dpy);

    XGrabKey(dpy, XKeysymToKeycode(dpy, XStringToKeysym("F1")), Mod1Mask, root, True, GrabModeAsync, GrabModeAsync);
    XGrabButton(dpy, 1, Mod1Mask, root, True, ButtonPressMask, GrabModeAsync, GrabModeAsync, None, None);
    XGrabButton(dpy, 3, Mod1Mask, root, True, ButtonPressMask, GrabModeAsync, GrabModeAsync, None, None);

    for(;;) {
        XNextEvent(dpy, &ev);
        if(ev.type == KeyPress && ev.xkey.subwindow != None)
            XRaiseWindow(dpy, ev.xkey.subwindow);
        else if(ev.type == ButtonPress && ev.xbutton.subwindow != None) {
            XGrabPointer(dpy, ev.xbutton.subwindow, True,
                    PointerMotionMask|ButtonReleaseMask, GrabModeAsync,
                    GrabModeAsync, None, None, CurrentTime);
            XGetWindowAttributes(dpy, ev.xbutton.subwindow, &attr);
            start = ev.xbutton;
        } else if(ev.type == MotionNotify) {
            int xdiff, ydiff;
            while(XCheckTypedEvent(dpy, MotionNotify, &ev));
            xdiff = ev.xbutton.x_root - start.x_root;
            ydiff = ev.xbutton.y_root - start.y_root;
            XMoveResizeWindow(dpy, ev.xmotion.window,
                attr.x + (start.button==1 ? xdiff : 0),
                attr.y + (start.button==1 ? ydiff : 0),
                MAX(1, attr.width + (start.button==3 ? xdiff : 0)),
                MAX(1, attr.height + (start.button==3 ? ydiff : 0)));
        } else if(ev.type == ButtonRelease)
            XUngrabPointer(dpy, CurrentTime);
    }
}

Display是Xorg的概念，在archlinux wiki上找到一个简短的解释(https://wiki.archlinux.org/index.php/Multihead):

Monitor refers to a physical display device, such as an LCD panel.

Screen refers to an X-Window screen (that is: a monitor attached to a display).

Display refers to a collection of screens that are in use at the same time showing parts of a single desktop (you can drag windows among all screens in a single display).

TODO