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tweener: make timeline loop indefinitely

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Tweener uses a clutter timeline to manage all active animations
running at a given moment.  The timeline is mopped up when no
animations are going any more.

Clutter requires timelines to have a finite duration, but since
animations can happen at any moment, no fixed duration can
accomodate the shell's needs.

To combat this problem, the tweener code picks a relatively
long duration: 1000 seconds. No string of animations should take
that long, so, in theory, that should be good enough.

Unfortunately, this tactic fails, in practice, when the user
suspends their machine, or VT switches.  An animation can take
much longer than 1000 seconds (~16 minutes) to complete in those
cases.  When the user resumes, or VT switches back the timeline
completes immediately (since it's already late) and tweener
never notices that the timeline stops ticking.

This commit changes the tweener timeline to automatically loop
back to 0 after completing, so that despite its fixed duration
property, it effectively never stops. Since the timeline loops,
its concept of elapsed time no longer increases monotonically,
so we now ignore it and track time ourselves with
GLib.get_monotonic_time().

This partially reverts commit
35764fa09e.

https://bugzilla.gnome.org/show_bug.cgi?id=653833
This commit is contained in:
Ray Strode 2012-02-16 13:29:46 -05:00
parent 05863227a6
commit 207abe9a2c
1 changed files with 11 additions and 3 deletions
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14
js/ui/tweener.js
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@ -1,6 +1,7 @@
// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
const Clutter = imports.gi.Clutter;
const GLib = imports.gi.GLib;
const Lang = imports.lang;
const Mainloop = imports.mainloop;
const Shell = imports.gi.Shell;
@ -209,9 +210,14 @@ const ClutterFrameTicker = new Lang.Class({
_init : function() {
// We don't have a finite duration; tweener will tell us to stop
// when we need to stop, so use 1000 seconds as "infinity"
// when we need to stop, so use 1000 seconds as "infinity", and
// set the timeline to loop. Doing this means we have to track
// time ourselves, since clutter timeline's time will cycle
// instead of strictly increase.
this._timeline = new Clutter.Timeline({ duration: 1000*1000 });
this._timeline.set_loop(true);
this._startTime = -1;
this._currentTime = -1;
this._timeline.connect('new-frame', Lang.bind(this,
function(timeline, frame) {
@ -234,17 +240,18 @@ const ClutterFrameTicker = new Lang.Class({
// That looks bad, so we always start at the first frame of the
// animation then only do frame dropping from there.
if (this._startTime < 0)
this._startTime = this._timeline.get_elapsed_time();
this._startTime = GLib.get_monotonic_time() / 1000.0;
// currentTime is in milliseconds
let perf_log = Shell.PerfLog.get_default();
this._currentTime = GLib.get_monotonic_time() / 1000.0 - this._startTime;
perf_log.event("tweener.framePrepareStart");
this.emit('prepare-frame');
perf_log.event("tweener.framePrepareDone");
},
getTime : function() {
return this._timeline.get_elapsed_time();
return this._currentTime;
},
start : function() {
@ -257,6 +264,7 @@ const ClutterFrameTicker = new Lang.Class({
stop : function() {
this._timeline.stop();
this._startTime = -1;
this._currentTime = -1;
global.end_work();
}
});