Performance|Widgets|libappfw: Optionally recycle children in a virtua…

…lized menu Provides better performance in menus where all the items use the same kind of widget.
skyjake · Jan 21, 2017 · 5087096 · 5087096
1 parent a88c946
commit 5087096
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Showing 2 changed files with 42 additions and 2 deletions.
diff --git a/doomsday/sdk/libappfw/include/de/framework/childwidgetorganizer.h b/doomsday/sdk/libappfw/include/de/framework/childwidgetorganizer.h
@@ -124,6 +124,16 @@ class LIBAPPFW_PUBLIC ChildWidgetOrganizer
      */
     void setVirtualizationEnabled(bool enabled);
 
+    /**
+     * Enables or disables child recycling. Deleted children will be put up for 
+     * recycling instead of being deleted, and new children will first be taken
+     * from the set of old recycled widgets.
+     *
+     * It is only possible to use this when all the items being managed have the
+     * same kind of widget representing them.
+     */
+    void setRecyclingEnabled(bool enabled);
+
     void setVirtualTopEdge(Rule const &topEdge);
 
     void setVisibleArea(Rule const &minimum, Rule const &maximum);

diff --git a/doomsday/sdk/libappfw/src/childwidgetorganizer.cpp b/doomsday/sdk/libappfw/src/childwidgetorganizer.cpp
@@ -71,6 +71,9 @@ DENG2_PIMPL(ChildWidgetOrganizer)
     float totalCorrection = 0;
     float correctionPerUnit = 0;
 
+    bool recyclingEnabled = false;
+    QList<GuiWidget *> recycledWidgets; // Not GL-deinitialized to facilitate fast reuse.
+
     Impl(Public *i, GuiWidget *c)
         : Base(i)
         , container(c)
@@ -79,6 +82,11 @@ DENG2_PIMPL(ChildWidgetOrganizer)
 
     ~Impl()
     {
+        foreach (GuiWidget *recycled, recycledWidgets)
+        {
+            GuiWidget::destroy(recycled);
+        }
+
         releaseRef(virtualTop);
         releaseRef(virtualMin);
         releaseRef(virtualMax);
@@ -130,7 +138,15 @@ DENG2_PIMPL(ChildWidgetOrganizer)
 
         ui::Item const &item = dataItems->at(pos);
 
-        GuiWidget *w = factory->makeItemWidget(item, container);
+        GuiWidget *w = nullptr;
+        if (recyclingEnabled && !recycledWidgets.isEmpty())
+        {
+            w = recycledWidgets.takeFirst();
+        }
+        else
+        {
+            w = factory->makeItemWidget(item, container);
+        }
         if (!w) return nullptr; // Unpresentable.
 
         // Update the widget immediately.
@@ -213,7 +229,16 @@ DENG2_PIMPL(ChildWidgetOrganizer)
     {
         //pendingStrutAdjust.remove(w);
         w->audienceForDeletion() -= this;
-        GuiWidget::destroy(w);
+
+        if (recyclingEnabled)
+        {
+            w->orphan();
+            recycledWidgets << w;
+        }
+        else
+        {
+            GuiWidget::destroy(w);
+        }
     }
 
     void clearWidgets()
@@ -580,6 +605,11 @@ void ChildWidgetOrganizer::setVirtualizationEnabled(bool enabled)
     }
 }
 
+void ChildWidgetOrganizer::setRecyclingEnabled(bool enabled)
+{
+    d->recyclingEnabled = enabled;
+}
+
 void ChildWidgetOrganizer::setVirtualTopEdge(Rule const &topEdge)
 {
     changeRef(d->virtualTop, topEdge);