179 lines
8.4 KiB
C
179 lines
8.4 KiB
C
/* TinyWM is written by Nick Welch <mack@incise.org>, 2005.
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*
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* This software is in the public domain
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* and is provided AS IS, with NO WARRANTY. */
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/* much of tinywm's purpose is to serve as a very basic example of how to do X
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* stuff and/or understand window managers, so i wanted to put comments in the
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* code explaining things, but i really hate wading through code that is
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* over-commented -- and for that matter, tinywm is supposed to be as concise
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* as possible, so having lots of comments just wasn't really fitting for it.
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* i want tinywm.c to be something you can just look at and go "wow, that's
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* it? cool!" so what i did was just copy it over to annotated.c and comment
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* the hell out of it. ahh, but now i have to make every code change twice!
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* oh well. i could always use some sort of script to process the comments out
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* of this and write it to tinywm.c ... nah.
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*/
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/* most X stuff will be included with Xlib.h, but a few things require other
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* headers, like Xmd.h, keysym.h, etc.
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*/
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#include <X11/Xlib.h>
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#define MAX(a, b) ((a) > (b) ? (a) : (b))
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int main()
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{
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Display * dpy;
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Window root;
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XWindowAttributes attr;
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/* we use this to save the pointer's state at the beginning of the
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* move/resize.
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*/
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XButtonEvent start;
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XEvent ev;
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/* return failure status if we can't connect */
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if(!(dpy = XOpenDisplay(0x0))) return 1;
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/* you'll usually be referencing the root window a lot. this is a somewhat
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* naive approach that will only work on the default screen. most people
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* only have one screen, but not everyone. if you run multi-head without
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* xinerama then you quite possibly have multiple screens. (i'm not sure
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* about vendor-specific implementations, like nvidia's)
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*
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* many, probably most window managers only handle one screen, so in
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* reality this isn't really *that* naive.
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*
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* if you wanted to get the root window of a specific screen you'd use
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* RootWindow(), but the user can also control which screen is our default:
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* if they set $DISPLAY to ":0.foo", then our default screen number is
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* whatever they specify "foo" as.
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*/
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root = DefaultRootWindow(dpy);
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/* you could also include keysym.h and use the XK_F1 constant instead of
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* the call to XStringToKeysym, but this method is more "dynamic." imagine
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* you have config files which specify key bindings. instead of parsing
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* the key names and having a huge table or whatever to map strings to XK_*
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* constants, you can just take the user-specified string and hand it off
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* to XStringToKeysym. XStringToKeysym will give you back the appropriate
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* keysym or tell you if it's an invalid key name.
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*
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* a keysym is basically a platform-independent numeric representation of a
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* key, like "F1", "a", "b", "L", "5", "Shift", etc. a keycode is a
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* numeric representation of a key on the keyboard sent by the keyboard
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* driver (or something along those lines -- i'm no hardware/driver expert)
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* to X. so we never want to hard-code keycodes, because they can and will
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* differ between systems.
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*/
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XGrabKey(dpy, XKeysymToKeycode(dpy, XStringToKeysym("F1")), Mod1Mask, root,
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True, GrabModeAsync, GrabModeAsync);
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/* XGrabKey and XGrabButton are basically ways of saying "when this
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* combination of modifiers and key/button is pressed, send me the events."
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* so we can safely assume that we'll receive Alt+F1 events, Alt+Button1
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* events, and Alt+Button3 events, but no others. You can either do
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* individual grabs like these for key/mouse combinations, or you can use
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* XSelectInput with KeyPressMask/ButtonPressMask/etc to catch all events
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* of those types and filter them as you receive them.
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*/
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XGrabButton(dpy, 1, Mod1Mask, root, True, ButtonPressMask, GrabModeAsync,
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GrabModeAsync, None, None);
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XGrabButton(dpy, 3, Mod1Mask, root, True, ButtonPressMask, GrabModeAsync,
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GrabModeAsync, None, None);
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for(;;)
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{
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/* this is the most basic way of looping through X events; you can be
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* more flexible by using XPending(), or ConnectionNumber() along with
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* select() (or poll() or whatever floats your boat).
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*/
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XNextEvent(dpy, &ev);
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/* this is our keybinding for raising windows. as i saw someone
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* mention on the ratpoison wiki, it is pretty stupid; however, i
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* wanted to fit some sort of keyboard binding in here somewhere, and
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* this was the best fit for it.
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*
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* i was a little confused about .window vs. .subwindow for a while,
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* but a little RTFMing took care of that. our passive grabs above
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* grabbed on the root window, so since we're only interested in events
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* for its child windows, we look at .subwindow. when subwindow
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* None, that means that the window the event happened in was the same
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* window that was grabbed on -- in this case, the root window.
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*/
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if(ev.type == KeyPress && ev.xkey.subwindow != None)
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XRaiseWindow(dpy, ev.xkey.subwindow);
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else if(ev.type == ButtonPress && ev.xbutton.subwindow != None)
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{
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/* now we take command of the pointer, looking for motion and
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* button release events.
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*/
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XGrabPointer(dpy, ev.xbutton.subwindow, True,
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PointerMotionMask|ButtonReleaseMask, GrabModeAsync,
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GrabModeAsync, None, None, CurrentTime);
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/* we "remember" the position of the pointer at the beginning of
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* our move/resize, and the size/position of the window. that way,
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* when the pointer moves, we can compare it to our initial data
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* and move/resize accordingly.
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*/
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XGetWindowAttributes(dpy, ev.xbutton.subwindow, &attr);
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start = ev.xbutton;
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}
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/* the only way we'd receive a motion notify event is if we already did
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* a pointer grab and we're in move/resize mode, so we assume that. */
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else if(ev.type == MotionNotify)
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{
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int xdiff, ydiff;
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/* here we "compress" motion notify events. if there are 10 of
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* them waiting, it makes no sense to look at any of them but the
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* most recent. in some cases -- if the window is really big or
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* things are just acting slowly in general -- failing to do this
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* can result in a lot of "drag lag."
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*
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* for window managers with things like desktop switching, it can
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* also be useful to compress EnterNotify events, so that you don't
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* get "focus flicker" as windows shuffle around underneath the
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* pointer.
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*/
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while(XCheckTypedEvent(dpy, MotionNotify, &ev));
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/* now we use the stuff we saved at the beginning of the
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* move/resize and compare it to the pointer's current position to
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* determine what the window's new size or position should be.
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*
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* if the initial button press was button 1, then we're moving.
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* otherwise it was 3 and we're resizing.
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*
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* we also make sure not to go negative with the window's
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* dimensions, resulting in "wrapping" which will make our window
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* something ridiculous like 65000 pixels wide (often accompanied
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* by lots of swapping and slowdown).
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*
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* even worse is if we get "lucky" and hit a width or height of
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* exactly zero, triggering an X error. so we specify a minimum
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* width/height of 1 pixel.
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*/
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xdiff = ev.xbutton.x_root - start.x_root;
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ydiff = ev.xbutton.y_root - start.y_root;
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XMoveResizeWindow(dpy, ev.xmotion.window,
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attr.x + (start.button==1 ? xdiff : 0),
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attr.y + (start.button==1 ? ydiff : 0),
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MAX(1, attr.width + (start.button==3 ? xdiff : 0)),
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MAX(1, attr.height + (start.button==3 ? ydiff : 0)));
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}
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/* like motion notifies, the only way we'll receive a button release is
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* during a move/resize, due to our pointer grab. this ends the
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* move/resize.
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*/
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else if(ev.type == ButtonRelease)
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XUngrabPointer(dpy, CurrentTime);
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}
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}
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