gnome-shell/js/ui/pointerWatcher.js

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// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
/* exported getPointerWatcher */
const GLib = imports.gi.GLib;
// We stop polling if the user is idle for more than this amount of time
var IDLE_TIME = 1000;
// This file implements a reasonably efficient system for tracking the position
// of the mouse pointer. We simply query the pointer from the X server in a loop,
// but we turn off the polling when the user is idle.
let _pointerWatcher = null;
function getPointerWatcher() {
if (_pointerWatcher == null)
_pointerWatcher = new PointerWatcher();
return _pointerWatcher;
}
var PointerWatch = class {
constructor(watcher, interval, callback) {
this.watcher = watcher;
this.interval = interval;
this.callback = callback;
}
// remove:
// remove this watch. This function may safely be called
// while the callback is executing.
remove() {
this.watcher._removeWatch(this);
}
};
var PointerWatcher = class {
constructor() {
this._idleMonitor = global.backend.get_core_idle_monitor();
this._idleMonitor.add_idle_watch(IDLE_TIME, this._onIdleMonitorBecameIdle.bind(this));
this._idle = this._idleMonitor.get_idletime() > IDLE_TIME;
this._watches = [];
this.pointerX = null;
this.pointerY = null;
}
// addWatch:
// @interval: hint as to the time resolution needed. When the user is
// not idle, the position of the pointer will be queried at least
// once every this many milliseconds.
// @callback to call when the pointer position changes - takes
// two arguments, X and Y.
//
// Set up a watch on the position of the mouse pointer. Returns a
// PointerWatch object which has a remove() method to remove the watch.
addWatch(interval, callback) {
// Avoid unreliably calling the watch for the current position
this._updatePointer();
let watch = new PointerWatch(this, interval, callback);
this._watches.push(watch);
this._updateTimeout();
return watch;
}
_removeWatch(watch) {
for (let i = 0; i < this._watches.length; i++) {
if (this._watches[i] == watch) {
this._watches.splice(i, 1);
this._updateTimeout();
return;
}
}
}
_onIdleMonitorBecameActive() {
this._idle = false;
this._updatePointer();
this._updateTimeout();
}
_onIdleMonitorBecameIdle() {
this._idle = true;
this._idleMonitor.add_user_active_watch(this._onIdleMonitorBecameActive.bind(this));
this._updateTimeout();
}
_updateTimeout() {
if (this._timeoutId) {
GLib.source_remove(this._timeoutId);
this._timeoutId = 0;
}
if (this._idle || this._watches.length == 0)
return;
let minInterval = this._watches[0].interval;
for (let i = 1; i < this._watches.length; i++)
minInterval = Math.min(this._watches[i].interval, minInterval);
this._timeoutId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, minInterval,
this._onTimeout.bind(this));
GLib.Source.set_name_by_id(this._timeoutId, '[gnome-shell] this._onTimeout');
}
_onTimeout() {
this._updatePointer();
return GLib.SOURCE_CONTINUE;
}
_updatePointer() {
let [x, y] = global.get_pointer();
if (this.pointerX == x && this.pointerY == y)
return;
this.pointerX = x;
this.pointerY = y;
for (let i = 0; i < this._watches.length;) {
let watch = this._watches[i];
watch.callback(x, y);
if (watch == this._watches[i]) // guard against self-removal
i++;
}
}
};