Add drag-open animation

This commit adds an animation for folders that makes clear that
they will open or expand soon. This is the case when the option to
open folders during drag operations is enabled and a user drags an
item on top of a folder.

The animation goes like this:
- Replace the folder's icon with the "folder-open" icon
- Go back to the folder's original icon
- Replace the folder's icon with the "folder-open" icon once more

1 files changed, 6 insertions, 0 deletions

diff --git a/src/kitemviews/kitemlistwidget.h b/src/kitemviews/kitemlistwidget.h
index 55d924719..fdfe5e78a 100644
--- a/src/kitemviews/kitemlistwidget.h
+++ b/src/kitemviews/kitemlistwidget.h
@@ -188,6 +188,12 @@ public:
      */
     virtual QPixmap createDragPixmap(const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr);
 
+    /**
+     * Starts an animation that makes clear that the item will be activated soon.
+     * @param timeUntilActivation time in milliseconds until the item will activate
+     */
+    virtual void startActivateSoonAnimation(int timeUntilActivation);
+
 Q_SIGNALS:
     void roleEditingCanceled(int index, const QByteArray &role, const QVariant &value);
     void roleEditingFinished(int index, const QByteArray &role, const QVariant &value);