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-rw-r--r--js/ui/pointerWatcher.js125
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diff --git a/js/ui/pointerWatcher.js b/js/ui/pointerWatcher.js
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+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+/* exported getPointerWatcher */
+
+const { GLib, Meta } = imports.gi;
+
+// 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 = Meta.IdleMonitor.get_core();
+ 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++;
+ }
+ }
+};