[gnome-maps/wip/drag-n-drop: 4/4] sidebar: Add drag-n-drop to route entries

[Jonas Danielsson <jonasdn src gnome org>]

commit f4505268e7f5057dc5a5e9173203da72c0efc149
Author: Jonas Danielsson <jonas threetimestwo org>
Date:   Thu Nov 27 07:18:25 2014 -0500

    sidebar: Add drag-n-drop to route entries

 data/gnome-maps.css |    4 ++
 src/sidebar.js      |  116 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+), 0 deletions(-)
---
diff --git a/data/gnome-maps.css b/data/gnome-maps.css
index d655e3a..fdb4899 100644
--- a/data/gnome-maps.css
+++ b/data/gnome-maps.css
@@ -2,6 +2,10 @@
     padding: 5px;
 }
 
+#dragged-entry {
+    color: #939695
+}
+
 .layer-radio-button {
     background-image: none;
     padding: 0px;
diff --git a/src/sidebar.js b/src/sidebar.js
index 2f585bb..648833a 100644
--- a/src/sidebar.js
+++ b/src/sidebar.js
@@ -21,6 +21,8 @@
  *         Mattias Bengtsson <mattias jc bengtsson gmail com>
  */
 
+const Cairo = imports.cairo;
+const Gdk = imports.gi.Gdk;
 const GObject = imports.gi.GObject;
 const Gtk = imports.gi.Gtk;
 const Lang = imports.lang;
@@ -177,6 +179,8 @@ const Sidebar = new Lang.Class({
                 Application.routeService.query.removePoint(row.get_index());
             });
         }
+
+        this._initRouteDragAndDrop(routeEntry);
     },
 
     _initInstructionList: function() {
@@ -227,5 +231,117 @@ const Sidebar = new Lang.Class({
 
         this._timeInfo.label = '';
         this._distanceInfo.label = '';
+    },
+
+    _onDragDrop: function(row, context, x, y, time) {
+        let routeEntry = row.get_child();
+        let srcPlace = this._draggedPoint.place;
+        let query = Application.routeService.query;
+        let srcIndex = query.getIndex(this._draggedPoint);
+        let destIndex = query.getIndex(routeEntry.point);
+        let step;
+
+        // Hold off on notifying the changes to query.points until
+        // we have re-arranged the places.
+        query.freeze_notify();
+
+        // Iterate over points and establish the new order of places
+        if (srcIndex < destIndex)
+            step = -1;
+        else
+            step = 1;
+
+        for (let i = destIndex; i !== (srcIndex + step); i += step) {
+            let tmpPlace = query.points[i].place;
+
+            query.points[i].place = srcPlace;
+            srcPlace = tmpPlace;
+        }
+
+        query.thaw_notify();
+        Gtk.drag_finish(context, true, false, time);
+        return true;
+    },
+
+    // Set the opacity of the row we are currently dragging above
+    // to semi transparent.
+    _onDragMotion: function(row, context, x, y, time) {
+        let routeEntry = row.get_child();
+
+        if (this._draggedPoint && this._draggedPoint !== routeEntry.point) {
+            row.opacity = 0.6;
+            Gdk.drag_status(context, Gdk.DragAction.MOVE, time);
+        } else
+            Gdk.drag_status(context, 0, time);
+        return true;
+    },
+
+    // Drag ends, show the dragged row again.
+    _onDragEnd: function(context, row) {
+        this._draggedPoint = null;
+        row.show();
+    },
+
+    // Drag begins, set the correct drag icon and hide the dragged row.
+    _onDragBegin: function(context, row) {
+        let routeEntry = row.get_child();
+        let dragEntry = this._dragWidget.get_child();
+
+        this._draggedPoint = routeEntry.point;
+        row.hide();
+        dragEntry.entry.text = routeEntry.entry.text;
+        Gtk.drag_set_icon_surface(context,
+                                  this._dragWidget.get_surface(), 0, 0);
+    },
+
+    // We add RouteEntry to an OffscreenWindow and paint the backgroind
+    // of the entry to be semi transparent.
+    // We can later use the GtkOffscreenWindow method get_surface to
+    // generate our drag icon.
+    _initDragWidget: function() {
+        let dragEntry = new RouteEntry.RouteEntry({ type: RouteEntry.Type.TO });
+        this._dragWidget = new Gtk.OffscreenWindow({ visible: true });
+
+        dragEntry.entry.name = 'dragged-entry';
+        dragEntry.app_paintable = true;
+        dragEntry.connect('draw', (function(widget, cr) {
+            cr.setSourceRGBA(0.0, 0.0, 0.0, 0.0);
+            cr.setOperator(Cairo.Operator.SOURCE);
+            cr.paint();
+            cr.setOperator(Cairo.Operator.OVER);
+        }).bind(this));
+
+        this._dragWidget.add(dragEntry);
+    },
+
+    // Set up drag and drop between RouteEntrys. The drag source is from a
+    // GtkEventBox that contains the start/end icon next in the entry. And
+    // the drag destination is the ListBox row.
+    _initRouteDragAndDrop: function(routeEntry) {
+        let dragIcon = routeEntry.iconEventBox;
+        let row = routeEntry.get_parent();
+
+        dragIcon.drag_source_set(Gdk.ModifierType.BUTTON1_MASK,
+                                 null,
+                                 Gdk.DragAction.MOVE);
+        dragIcon.drag_source_add_image_targets();
+
+        row.drag_dest_set(Gtk.DestDefaults.MOTION,
+                           null,
+                           Gdk.DragAction.MOVE);
+        row.drag_dest_add_image_targets();
+
+        dragIcon.connect('drag-begin', (function(icon, context) {
+            this._onDragBegin(context, row);
+        }).bind(this));
+        dragIcon.connect('drag-end', (function(icon, context) {
+            this._onDragEnd(context, row);
+        }).bind(this));
+
+        row.connect('drag-leave', row.set_opacity.bind(row, 1.0));
+        row.connect('drag-motion', this._onDragMotion.bind(this));
+        row.connect('drag-drop', this._onDragDrop.bind(this));
+
+        this._initDragWidget();
     }
 });