[gnome-documents] lokview: Clamp zoom levels the same way as the Evince view

[Pranav Kant <pranavk src gnome org>]

commit a7c3fd5c0ff5e9bd17521e656e44e347ef702ce7
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Dec 15 17:44:22 2015 +0100

    lokview: Clamp zoom levels the same way as the Evince view
    
    https://bugzilla.gnome.org/show_bug.cgi?id=753686

 src/lokview.js |   23 +++++++++++++++++++----
 1 files changed, 19 insertions(+), 4 deletions(-)
---
diff --git a/src/lokview.js b/src/lokview.js
index 4cc8eab..c23add9 100644
--- a/src/lokview.js
+++ b/src/lokview.js
@@ -49,6 +49,9 @@ const View = imports.view;
 const WindowMode = imports.windowMode;
 const Documents = imports.documents;
 
+const ZOOM_IN_FACTOR = 1.2;
+const ZOOM_OUT_FACTOR = (1.0/ZOOM_IN_FACTOR);
+
 const openDocumentFormats = ['application/vnd.oasis.opendocument.text',
                              'application/vnd.oasis.opendocument.text-template',
                              'application/vnd.oasis.opendocument.text-web',
@@ -121,17 +124,21 @@ const LOKView = new Lang.Class({
         this.show_all();
 
         this._zoomIn = Application.application.lookup_action('zoom-in');
+        this.view.connect('notify::can-zoom-in', Lang.bind(this,
+            this._onCanZoomInChanged));
         let zoomInId = this._zoomIn.connect('activate', Lang.bind(this,
             function() {
-                let zoomLevel = this.view.get_zoom();
-                this.view.set_zoom(zoomLevel * 2);
+                let zoomLevel = this.view.get_zoom() * ZOOM_IN_FACTOR;
+                this.view.set_zoom(zoomLevel);
             }));
 
         this._zoomOut = Application.application.lookup_action('zoom-out');
+        this.view.connect('notify::can-zoom-out', Lang.bind(this,
+            this._onCanZoomOutChanged));
         let zoomOutId = this._zoomOut.connect('activate', Lang.bind(this,
             function() {
-                let zoomLevel = this.view.get_zoom();
-                this.view.set_zoom(zoomLevel / 2);
+                let zoomLevel = this.view.get_zoom() * ZOOM_OUT_FACTOR;
+                this.view.set_zoom(zoomLevel);
             }));
 
         this._copy = Application.application.lookup_action('copy');
@@ -150,6 +157,14 @@ const LOKView = new Lang.Class({
            }));
     },
 
+    _onCanZoomInChanged: function() {
+        this._zoomIn.enabled = this.view.can_zoom_in;
+    },
+
+    _onCanZoomOutChanged: function() {
+        this._zoomOut.enabled = this.view.can_zoom_out;
+    },
+
     _onCopyActivated: function() {
         let [selectedText, mimeType] = this.view.copy_selection('text/plain;charset=utf-8');
         let display = Gdk.Display.get_default();