[gnome-shell] telepathyClient: Pin the scrollbar to the bottom

[Adel Gadllah <agadllah src gnome org>]

commit a0a83428cfb21b12368d10711fabf9dd698d5a24
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Wed Mar 9 13:56:35 2011 +0100

    telepathyClient: Pin the scrollbar to the bottom
    
    When new messages come in we want to scroll down so that the user
    sees the incoming messages. The current implementation does not work
    because it relies on a synchronous allocation hack which does not work
    for unmapped notifications.
    
    Fix that by connecting to adjustment::changed and scroll whenever the
    adjustment changes which equals "new messages", "new timestamp" or
    "presense change", but don't interference with the user's scroll actions
    i.e when the user scrolls back to read something don't scroll to the bottom.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=614977

 js/ui/messageTray.js     |   29 ++++++++++++++++-------------
 js/ui/telepathyClient.js |   11 ++++++++++-
 2 files changed, 26 insertions(+), 14 deletions(-)
---
diff --git a/js/ui/messageTray.js b/js/ui/messageTray.js
index 39b90f8..4f25122 100644
--- a/js/ui/messageTray.js
+++ b/js/ui/messageTray.js
@@ -518,25 +518,28 @@ Notification.prototype = {
         this._updated();
     },
 
+    _createScrollArea: function() {
+        this.actor.add_style_class_name('multi-line-notification');
+        this._scrollArea = new St.ScrollView({ name: 'notification-scrollview',
+                                               vscrollbar_policy: Gtk.PolicyType.AUTOMATIC,
+                                               hscrollbar_policy: Gtk.PolicyType.NEVER,
+                                               vfade: true });
+        this.actor.add(this._scrollArea, { row: 1, col: 1 });
+        this._contentArea = new St.BoxLayout({ name: 'notification-body',
+                                               vertical: true });
+        this._scrollArea.add_actor(this._contentArea);
+        // If we know the notification will be expandable, we need to add
+        // the banner text to the body as the first element.
+        this._addBannerBody();
+    },
+
     // addActor:
     // @actor: actor to add to the body of the notification
     //
     // Appends @actor to the notification's body
     addActor: function(actor, style) {
         if (!this._scrollArea) {
-            this.actor.add_style_class_name('multi-line-notification');
-            this._scrollArea = new St.ScrollView({ name: 'notification-scrollview',
-                                                   vscrollbar_policy: Gtk.PolicyType.AUTOMATIC,
-                                                   hscrollbar_policy: Gtk.PolicyType.NEVER,
-                                                   vfade: true });
-            this.actor.add(this._scrollArea, { row: 1,
-                                               col: 1 });
-            this._contentArea = new St.BoxLayout({ name: 'notification-body',
-                                                   vertical: true });
-            this._scrollArea.add_actor(this._contentArea);
-            // If we know the notification will be expandable, we need to add
-            // the banner text to the body as the first element.
-            this._addBannerBody();
+            this._createScrollArea();
         }
 
         this._contentArea.add(actor, style ? style : {});
diff --git a/js/ui/telepathyClient.js b/js/ui/telepathyClient.js
index d835d3e..7dd972e 100644
--- a/js/ui/telepathyClient.js
+++ b/js/ui/telepathyClient.js
@@ -279,6 +279,16 @@ Notification.prototype = {
         this._responseEntry.clutter_text.connect('activate', Lang.bind(this, this._onEntryActivated));
         this.setActionArea(this._responseEntry);
 
+        this._oldMaxScrollAdjustment = 0;
+        this._createScrollArea();
+
+        this._scrollArea.vscroll.adjustment.connect('changed', Lang.bind(this, function(adjustment) {
+            let currentValue = adjustment.value + adjustment.page_size;
+            if (currentValue == this._oldMaxScrollAdjustment)
+                this.scrollTo(St.Side.BOTTOM);
+            this._oldMaxScrollAdjustment = adjustment.upper;
+        }));
+
         this._history = [];
         this._timestampTimeoutId = 0;
     },
@@ -305,7 +315,6 @@ Notification.prototype = {
 
         let body = this.addBody(text);
         body.add_style_class_name(style);
-        this.scrollTo(St.Side.BOTTOM);
 
         this._history.unshift({ actor: body, time: timestamp, realMessage: true });