[gnome-shell/wip/sass] ibusManager: Preload all ibus input sources in user configuration

[Jakub Steiner <jimmac src gnome org>]

commit ef7b69fdcd8a69909789a8bdab03075ebd4812fd
Author: Takao Fujiwara <tfujiwar redhat com>
Date:   Mon Nov 10 19:09:08 2014 +0900

    ibusManager: Preload all ibus input sources in user configuration
    
    Normally users switch xkb input sources and ibus input sources.
    But currently the first input source only is running. It's also good
    to preload all ibus engines in the logging session so that users switch
    input sources quickly without the launching time of input sources.
    
    The following is the ibus change:
    https://github.com/ibus/ibus/commit/cff35929a9
    
    https://bugzilla.gnome.org/show_bug.cgi?id=695428

 js/misc/ibusManager.js   |   45 +++++++++++++++++++++++++++++++++++++++++++--
 js/ui/status/keyboard.js |    4 ++++
 2 files changed, 47 insertions(+), 2 deletions(-)
---
diff --git a/js/misc/ibusManager.js b/js/misc/ibusManager.js
index 9571e0b..06d808d 100644
--- a/js/misc/ibusManager.js
+++ b/js/misc/ibusManager.js
@@ -1,13 +1,14 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 
 const Gio = imports.gi.Gio;
+const GLib = imports.gi.GLib;
 const Lang = imports.lang;
+const Mainloop = imports.mainloop;
 const Signals = imports.signals;
 
 try {
     var IBus = imports.gi.IBus;
-    if (!('new_async' in IBus.Bus))
-        throw "IBus version is too old";
+    _checkIBusVersion();
     const IBusCandidatePopup = imports.ui.ibusCandidatePopup;
 } catch (e) {
     var IBus = null;
@@ -16,6 +17,22 @@ try {
 
 let _ibusManager = null;
 
+function _checkIBusVersion() {
+    var requiredMajor = 1;
+    var requiredMinor = 5;
+    var requiredMicro = 2;
+
+    if ((IBus.MAJOR_VERSION > requiredMajor) ||
+        (IBus.MAJOR_VERSION == requiredMajor && IBus.MINOR_VERSION > requiredMinor) ||
+        (IBus.MAJOR_VERSION == requiredMajor && IBus.MINOR_VERSION == requiredMinor &&
+         IBus.MICRO_VERSION >= requiredMicro))
+        return;
+
+    throw "Found IBus version %d.%d.%d but required is %d.%d.%d".
+        format(IBus.MAJOR_VERSION, IBus.MINOR_VERSION, IBus.MINOR_VERSION,
+               requiredMajor, requiredMinor, requiredMicro);
+}
+
 function getIBusManager() {
     if (_ibusManager == null)
         _ibusManager = new IBusManager();
@@ -28,6 +45,7 @@ const IBusManager = new Lang.Class({
     // This is the longest we'll keep the keyboard frozen until an input
     // source is active.
     _MAX_INPUT_SOURCE_ACTIVATION_TIME: 4000, // ms
+    _PRELOAD_ENGINES_DELAY_TIME: 30, // sec
 
     _init: function() {
         if (!IBus)
@@ -42,6 +60,7 @@ const IBusManager = new Lang.Class({
         this._ready = false;
         this._registerPropertiesId = 0;
         this._currentEngineName = null;
+        this._preloadEnginesId = 0;
 
         this._ibus = IBus.Bus.new_async();
         this._ibus.connect('connected', Lang.bind(this, this._onConnected));
@@ -176,5 +195,27 @@ const IBusManager = new Lang.Class({
         this._ibus.set_global_engine_async(id, this._MAX_INPUT_SOURCE_ACTIVATION_TIME,
                                            null, callback);
     },
+
+    preloadEngines: function(ids) {
+        if (!IBus || !this._ibus || ids.length == 0)
+            return;
+
+        if (this._preloadEnginesId != 0) {
+            Mainloop.source_remove(this._preloadEnginesId);
+            this._preloadEnginesId = 0;
+        }
+
+        this._preloadEnginesId =
+            Mainloop.timeout_add_seconds(this._PRELOAD_ENGINES_DELAY_TIME,
+                                         Lang.bind(this, function() {
+                                             this._ibus.preload_engines_async(
+                                                 ids,
+                                                 -1,
+                                                 null,
+                                                 null);
+                                             this._preloadEnginesId = 0;
+                                             return GLib.SOURCE_REMOVE;
+                                         }));
+    },
 });
 Signals.addSignalMethods(IBusManager.prototype);
diff --git a/js/ui/status/keyboard.js b/js/ui/status/keyboard.js
index 8cb8cc9..4ae8ba1 100644
--- a/js/ui/status/keyboard.js
+++ b/js/ui/status/keyboard.js
@@ -381,6 +381,10 @@ const InputSourceManager = new Lang.Class({
 
         if (this._mruSources.length > 0)
             this._mruSources[0].activate();
+
+        // All ibus engines are preloaded here to reduce the launching time
+        // when users switch the input sources.
+        this._ibusManager.preloadEngines(Object.keys(this._ibusSources));
     },
 
     _makeEngineShortName: function(engineDesc) {