libdeng2|Widget: Added Deletion audience; children can be reordered

skyjake · Aug 16, 2013 · 808711a · 808711a
1 parent 4ddd2a3
commit 808711a
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Showing 2 changed files with 48 additions and 0 deletions.
diff --git a/doomsday/libdeng2/include/de/widgets/widget.h b/doomsday/libdeng2/include/de/widgets/widget.h
@@ -79,6 +79,11 @@ class DENG2_PUBLIC Widget
 
     typedef WidgetList Children;
 
+    /**
+     * Notified when the widget is about to be deleted.
+     */
+    DENG2_DEFINE_AUDIENCE(Deletion, void widgetBeingDeleted(Widget &widget))
+
     /**
      * Notified when the widget's parent changes.
      */
@@ -182,9 +187,11 @@ class DENG2_PUBLIC Widget
     // Tree organization.
     void clear();
     Widget &add(Widget *child);
+    Widget &insertBefore(Widget *child, Widget const &otherChild);
     Widget *remove(Widget &child);
     Widget *find(String const &name);
     Widget const *find(String const &name) const;
+    void moveChildBefore(Widget *child, Widget const &otherChild);
     Children children() const;
     dsize childCount() const;
     Widget *parent() const;

diff --git a/doomsday/libdeng2/src/widgets/widget.cpp b/doomsday/libdeng2/src/widgets/widget.cpp
@@ -75,6 +75,9 @@ Widget::~Widget()
     {
         d->parent->remove(*this);
     }
+
+    // Notify everyone else.
+    DENG2_FOR_AUDIENCE(Deletion, i) i->widgetBeingDeleted(*this);
 }
 
 Id Widget::id() const
@@ -260,6 +263,15 @@ Widget &Widget::add(Widget *child)
     return *child;
 }
 
+Widget &Widget::insertBefore(Widget *child, Widget const &otherChild)
+{    
+    DENG2_ASSERT(child != &otherChild);
+
+    add(child);
+    moveChildBefore(child, otherChild);
+    return *child;
+}
+
 Widget *Widget::remove(Widget &child)
 {
     DENG2_ASSERT(child.d->parent == this);
@@ -306,6 +318,35 @@ Widget const *Widget::find(String const &name) const
     return const_cast<Widget *>(this)->find(name);
 }
 
+void Widget::moveChildBefore(Widget *child, Widget const &otherChild)
+{
+    if(child == &otherChild) return; // invalid
+
+    int from = -1;
+    int to = -1;
+
+    // Note: O(n)
+    for(int i = 0; i < d->children.size() && (from < 0 || to < 0); ++i)
+    {
+        if(d->children[i] == child)
+        {
+            from = i;
+        }
+        if(d->children[i] == &otherChild)
+        {
+            to = i;
+        }
+    }
+
+    DENG2_ASSERT(from != -1);
+    DENG2_ASSERT(to != -1);
+
+    d->children.removeAt(from);
+    if(to > from) to--;
+
+    d->children.insert(to, child);
+}
+
 Widget *Widget::parent() const
 {
     return d->parent;