[gnome-shell] panel: Rewrite the app menu to use the new "sync" pattern

[Jasper St. Pierre <jstpierre src gnome org>]

commit 7563e0474319ca3ff05072d39b22b6ed9287e68e
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Aug 13 07:41:44 2013 -0400

    panel: Rewrite the app menu to use the new "sync" pattern
    
    The existing app menu was a kludge of legacy code that tried to manage
    a bunch of state, and had a number of issues:
    
     * It didn't properly manage visibility when combined with multiple
       apps and the overview.
    
     * It didn't properly manage reactivity when tabbing away from a busy
       app to another app.
    
     * It didn't properly disconnect signals when going from one app
       to nothing.
    
    and countless others. Rewrite it to use the new "sync" code pattern,
    where we centralize all state management and do transitions from that,
    rather than strange and quirky control flow.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=705898

 js/ui/panel.js |  145 ++++++++++++++++++++------------------------------------
 1 files changed, 51 insertions(+), 94 deletions(-)
---
diff --git a/js/ui/panel.js b/js/ui/panel.js
index ed4931f..3f20781 100644
--- a/js/ui/panel.js
+++ b/js/ui/panel.js
@@ -189,7 +189,6 @@ const AppMenuButton = new Lang.Class({
 
         this.actor.bind_property("reactive", this.actor, "can-focus", 0);
         this.actor.reactive = false;
-        this._targetIsCurrent = false;
 
         this._container = new Shell.GenericContainer();
         bin.set_child(this._container);
@@ -224,12 +223,8 @@ const AppMenuButton = new Lang.Class({
         this._visible = !Main.overview.visible;
         if (!this._visible)
             this.actor.hide();
-        this._overviewHidingId = Main.overview.connect('hiding', Lang.bind(this, function () {
-            this.show();
-        }));
-        this._overviewShowingId = Main.overview.connect('showing', Lang.bind(this, function () {
-            this.hide();
-        }));
+        this._overviewHidingId = Main.overview.connect('hiding', Lang.bind(this, this._sync));
+        this._overviewShowingId = Main.overview.connect('showing', Lang.bind(this, this._sync));
 
         this._stop = true;
 
@@ -252,14 +247,8 @@ const AppMenuButton = new Lang.Class({
             return;
 
         this._visible = true;
-        this.actor.show();
-
-        if (!this._targetIsCurrent)
-            return;
-
         this.actor.reactive = true;
-
-        Tweener.removeTweens(this.actor);
+        this.actor.show();
         Tweener.addTween(this.actor,
                          { opacity: 255,
                            time: Overview.ANIMATION_TIME,
@@ -272,12 +261,6 @@ const AppMenuButton = new Lang.Class({
 
         this._visible = false;
         this.actor.reactive = false;
-        if (!this._targetIsCurrent) {
-            this.actor.hide();
-            return;
-        }
-
-        Tweener.removeTweens(this.actor);
         Tweener.addTween(this.actor,
                          { opacity: 0,
                            time: Overview.ANIMATION_TIME,
@@ -306,6 +289,9 @@ const AppMenuButton = new Lang.Class({
     },
 
     _syncIcon: function() {
+        if (!this._targetApp)
+            return;
+
         let icon = this._targetApp.get_faded_icon(2 * PANEL_ICON_SIZE, this._iconBox.text_direction);
         this._iconBox.set_child(icon);
     },
@@ -332,7 +318,6 @@ const AppMenuButton = new Lang.Class({
             return;
 
         this._stop = true;
-        this.actor.reactive = true;
 
         if (this._spinner == null)
             return;
@@ -352,7 +337,6 @@ const AppMenuButton = new Lang.Class({
 
     startAnimation: function() {
         this._stop = false;
-        this.actor.reactive = false;
 
         if (this._spinner == null)
             return;
@@ -448,98 +432,70 @@ const AppMenuButton = new Lang.Class({
         this._sync();
     },
 
-    _sync: function() {
+    _findTargetApp: function() {
+        let workspace = global.screen.get_active_workspace();
         let tracker = Shell.WindowTracker.get_default();
         let focusedApp = tracker.focus_app;
-        let lastStartedApp = null;
-        let workspace = global.screen.get_active_workspace();
+        if (focusedApp && focusedApp.is_on_workspace(workspace))
+            return focusedApp;
+
         for (let i = 0; i < this._startingApps.length; i++)
             if (this._startingApps[i].is_on_workspace(workspace))
-                lastStartedApp = this._startingApps[i];
-
-        let targetApp = focusedApp != null ? focusedApp : lastStartedApp;
+                return this._startingApps[i];
 
-        if (targetApp == null) {
-            if (!this._targetIsCurrent)
-                return;
-
-            this.actor.reactive = false;
-            this._targetIsCurrent = false;
-
-            Tweener.removeTweens(this.actor);
-            Tweener.addTween(this.actor, { opacity: 0,
-                                           time: Overview.ANIMATION_TIME,
-                                           transition: 'easeOutQuad' });
-            return;
-        }
+        return null;
+    },
 
-        if (!targetApp.is_on_workspace(workspace))
-            return;
+    _sync: function() {
+        let targetApp = this._findTargetApp();
 
-        if (!this._targetIsCurrent) {
-            this.actor.reactive = true;
-            this._targetIsCurrent = true;
+        if (this._targetApp != targetApp) {
+            if (this._appMenuNotifyId) {
+                this._targetApp.disconnect(this._appMenuNotifyId);
+                this._appMenuNotifyId = 0;
+            }
+            if (this._actionGroupNotifyId) {
+                this._targetApp.disconnect(this._actionGroupNotifyId);
+                this._actionGroupNotifyId = 0;
+            }
 
-            Tweener.removeTweens(this.actor);
-            Tweener.addTween(this.actor, { opacity: 255,
-                                           time: Overview.ANIMATION_TIME,
-                                           transition: 'easeOutQuad' });
-        }
+            this._targetApp = targetApp;
 
-        if (targetApp == this._targetApp) {
-            if (targetApp &&
-                targetApp.get_state() != Shell.AppState.STARTING &&
-                targetApp.get_state() != Shell.AppState.BUSY) {
-                this.stopAnimation();
-                this._maybeSetMenu();
-            } else if (targetApp &&
-                       targetApp.get_state() == Shell.AppState.BUSY) {
-                this.startAnimation();
+            if (this._targetApp) {
+                this._appMenuNotifyId = this._targetApp.connect('notify::menu', Lang.bind(this, this._sync));
+                this._actionGroupNotifyId = this._targetApp.connect('notify::action-group', Lang.bind(this, 
this._sync));
+                this._label.setText(this._targetApp.get_name());
+                this.actor.set_accessible_name(this._targetApp.get_name());
             }
-            return;
-        }
-
-        if (this._spinner)
-            this._spinner.actor.hide();
-        if (this._iconBox.child != null)
-            this._iconBox.child.destroy();
-        this._iconBox.hide();
-        this._arrow.hide();
-        this._label.setText('');
-
-        if (this._appMenuNotifyId)
-            this._targetApp.disconnect(this._appMenuNotifyId);
-        if (this._actionGroupNotifyId)
-            this._targetApp.disconnect(this._actionGroupNotifyId);
-        if (targetApp) {
-            this._appMenuNotifyId = targetApp.connect('notify::menu', Lang.bind(this, this._sync));
-            this._actionGroupNotifyId = targetApp.connect('notify::action-group', Lang.bind(this, 
this._sync));
-        } else {
-            this._appMenuNotifyId = 0;
-            this._actionGroupNotifyId = 0;
         }
 
-        this._targetApp = targetApp;
-        this._label.setText(targetApp.get_name());
-        this.actor.set_accessible_name(targetApp.get_name());
-
-        this._syncIcon();
-        this._arrow.show();
-        this._iconBox.show();
+        let visible = (this._targetApp != null && !Main.overview.visibleTarget);
+        if (visible)
+            this.show();
+        else
+            this.hide();
 
-        if (targetApp.get_state() == Shell.AppState.STARTING ||
-            targetApp.get_state() == Shell.AppState.BUSY)
+        let isBusy = (this._targetApp != null &&
+                      (this._targetApp.get_state() == Shell.AppState.STARTING ||
+                       this._targetApp.get_state() == Shell.AppState.BUSY));
+        if (isBusy)
             this.startAnimation();
         else
-            this._maybeSetMenu();
+            this.stopAnimation();
 
+        this.actor.reactive = (visible && !isBusy);
+
+        this._syncIcon();
+        this._maybeSetMenu();
         this.emit('changed');
     },
 
     _maybeSetMenu: function() {
         let menu;
 
-        if (this._targetApp.action_group && this._targetApp.menu) {
+        if (this._targetApp == null) {
+            menu = null;
+        } else if (this._targetApp.action_group && this._targetApp.menu) {
             if (this.menu instanceof RemoteMenu.RemoteMenu &&
                 this.menu.actionGroup == this._targetApp.action_group)
                 return;
@@ -551,7 +507,7 @@ const AppMenuButton = new Lang.Class({
             }));
 
         } else {
-            if (this.menu.isDummyQuitMenu)
+            if (this.menu && this.menu.isDummyQuitMenu)
                 return;
 
             // fallback to older menu
@@ -563,7 +519,8 @@ const AppMenuButton = new Lang.Class({
         }
 
         this.setMenu(menu);
-        this._menuManager.addMenu(menu);
+        if (menu)
+            this._menuManager.addMenu(menu);
     },
 
     destroy: function() {