AppDisplay: allow changing categories by scrolling over them

Respond to scrolling over the app categories by changing them, so
it is not required to point and click, or to use the All view.

https://bugzilla.gnome.org/show_bug.cgi?id=643426

diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index ebc19d156e2e348713c18e5cf9d3a8de0ac5d6d5..6fe12f299dc924f1edc97a1297596d004923ce5a 100644 (file)
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -109,7 +109,14 @@ ViewByCategories.prototype = {
 
         this._view = new AlphabeticalView();
 
-        this._filters = new St.BoxLayout({ vertical: true });
+        // categories can be -1 (the All view) or 0...n-1, where n
+        // is the number of sections
+        // -2 is a flag to indicate that nothing is selected
+        // (used only before the actor is mapped the first time)
+        this._currentCategory = -2;
+        this._filters = new St.BoxLayout({ vertical: true, reactive: true });
+        this._filters.connect('scroll-event', Lang.bind(this, this._scrollFilter));
+
         this.actor.add(this._view.actor, { expand: true, x_fill: true, y_fill: true });
         this.actor.add(this._filters, { expand: false, y_fill: false, y_align: St.Align.START });
 
@@ -123,7 +130,20 @@ ViewByCategories.prototype = {
         this._sections = [];
     },
 
+    _scrollFilter: function(actor, event) {
+        let direction = event.get_scroll_direction();
+        if (direction == Clutter.ScrollDirection.UP)
+            this._selectCategory(Math.max(this._currentCategory - 1, -1))
+        else if (direction == Clutter.ScrollDirection.DOWN)
+            this._selectCategory(Math.min(this._currentCategory + 1, this._sections.length - 1));
+    },
+
     _selectCategory: function(num) {
+        if (this._currentCategory == num) // nothing to do
+            return;
+
+        this._currentCategory = num;
+
         if (num != -1)
             this._allFilter.remove_style_pseudo_class('selected');
         else