From f0ae353c9ef526e91faeed9376528bd6250066a0 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Thu, 13 Feb 2020 21:49:14 +0100
Subject: [PATCH] LibGUI: Allow dropping drags on AbstractView

You can now drop things on an AbstractView, which will ask its model if
the drag is acceptable to drop at the index where it's dropped.

If it's accepted by the model, the view will fire the on_drop hook.
---
 Libraries/LibGUI/AbstractView.cpp | 15 +++++++++++++++
 Libraries/LibGUI/AbstractView.h   |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/Libraries/LibGUI/AbstractView.cpp b/Libraries/LibGUI/AbstractView.cpp
index 5929f16762..ba770efaa3 100644
--- a/Libraries/LibGUI/AbstractView.cpp
+++ b/Libraries/LibGUI/AbstractView.cpp
@@ -326,4 +326,19 @@ void AbstractView::context_menu_event(ContextMenuEvent& event)
         on_context_menu_request(index, event);
 }
 
+void AbstractView::drop_event(DropEvent& event)
+{
+    event.accept();
+
+    if (!model())
+        return;
+
+    auto index = index_at_event_position(event.position());
+    if (!index.is_valid())
+        return;
+
+    if (on_drop)
+        on_drop(index, event);
+}
+
 }
diff --git a/Libraries/LibGUI/AbstractView.h b/Libraries/LibGUI/AbstractView.h
index c098e661f6..8e9b52d71e 100644
--- a/Libraries/LibGUI/AbstractView.h
+++ b/Libraries/LibGUI/AbstractView.h
@@ -67,6 +67,7 @@ public:
     Function<void(const ModelIndex&)> on_activation;
     Function<void(const ModelIndex&)> on_selection;
     Function<void(const ModelIndex&, const ContextMenuEvent&)> on_context_menu_request;
+    Function<void(const ModelIndex&, const DropEvent&)> on_drop;
 
     Function<OwnPtr<ModelEditingDelegate>(const ModelIndex&)> aid_create_editing_delegate;
 
@@ -83,6 +84,7 @@ protected:
     virtual void mouseup_event(MouseEvent&) override;
     virtual void doubleclick_event(MouseEvent&) override;
     virtual void context_menu_event(ContextMenuEvent&) override;
+    virtual void drop_event(DropEvent&) override;
 
     virtual void did_scroll() override;
     void activate(const ModelIndex&);