[gnome-maps] Add scale ruler

[Jonas Danielsson <jonasdn src gnome org>]

commit ec85127a77525e897e3cc86f3a6692776ed4a77d
Author: Jonas Danielsson <jonas threetimestwo org>
Date:   Mon Feb 1 10:24:06 2016 +0100

    Add scale ruler
    
    Champlain has support for adding a scale ruler. It also supports
    different units. Miles vs Kilometers. This commit adds a scale to Maps
    and checks the LC_MEASUREMENT locale to determine the unit.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=739363

 data/ui/help-overlay.ui |   19 +++++++++++++------
 src/mainWindow.js       |    4 ++++
 src/mapView.js          |   22 ++++++++++++++++++++++
 3 files changed, 39 insertions(+), 6 deletions(-)
---
diff --git a/data/ui/help-overlay.ui b/data/ui/help-overlay.ui
index e1ed46a..ad53c77 100644
--- a/data/ui/help-overlay.ui
+++ b/data/ui/help-overlay.ui
@@ -58,12 +58,19 @@
               </object>
             </child>
             <child>
-               <object class="GtkShortcutsShortcut">
-                 <property name="visible">1</property>
-                 <property name="title" translatable="yes" context="shortcut window">Go to current 
location</property>
-                 <property name="accelerator">&lt;Primary&gt;L</property>
-               </object>
-             </child>
+              <object class="GtkShortcutsShortcut">
+                <property name="visible">1</property>
+                <property name="title" translatable="yes" context="shortcut-window">Toggle scale</property>
+                <property name="accelerator">&lt;Primary&gt;S</property>
+              </object>
+            </child>
+            <child>
+              <object class="GtkShortcutsShortcut">
+                <property name="visible">1</property>
+                <property name="title" translatable="yes" context="shortcut window">Go to current 
location</property>
+                <property name="accelerator">&lt;Primary&gt;L</property>
+              </object>
+            </child>
           </object>
         </child>
       </object>
diff --git a/src/mainWindow.js b/src/mainWindow.js
index a59536a..39c1de1 100644
--- a/src/mainWindow.js
+++ b/src/mainWindow.js
@@ -200,6 +200,10 @@ const MainWindow = new Lang.Class({
                 accels: ['minus', '<Primary>minus', 'KP_Subtract', '<Primary>KP_Subtract'],
                 onActivate:  this._mapView.view.zoom_out.bind(this._mapView.view)
             },
+            'toggle-scale': {
+                accels: ['<Primary>S'],
+                onActivate:  this._mapView.toggleScale.bind(this._mapView)
+            },
             'find': {
                 accels: ['<Primary>F'],
                 onActivate: this._placeEntry.grab_focus.bind(this._placeEntry)
diff --git a/src/mapView.js b/src/mapView.js
index 5d3d2a5..eb13081 100644
--- a/src/mapView.js
+++ b/src/mapView.js
@@ -100,6 +100,22 @@ const MapView = new Lang.Class({
         this._connectRouteSignals();
     },
 
+    _initScale: function(view) {
+        this._scale = new Champlain.Scale({ visible: true });
+        this._scale.connect_view(view);
+
+        if (Utils.getMeasurementSystem() === Utils.METRIC_SYSTEM)
+            this._scale.unit = Champlain.Unit.KM;
+        else
+            this._scale.unit = Champlain.Unit.MILES;
+
+        this._scale.set_x_expand(true);
+        this._scale.set_y_expand(true);
+        this._scale.set_x_align(Clutter.ActorAlign.START);
+        this._scale.set_y_align(Clutter.ActorAlign.END);
+        view.add_child(this._scale);
+    },
+
     _initView: function(opening) {
         let view = this.get_view();
         view.zoom_level = 3;
@@ -117,6 +133,8 @@ const MapView = new Lang.Class({
                 view.min_zoom_level = MapMinZoom;
             }
         }).bind(this));
+
+        this._initScale(view);
         return view;
     },
 
@@ -198,6 +216,10 @@ const MapView = new Lang.Class({
         }).bind(this));
     },
 
+    toggleScale: function() {
+        this._scale.visible = !this._scale.visible;
+    },
+
     openShapeLayers: function(files) {
         let bbox = new Champlain.BoundingBox();
         let ret = true;