From d9080cd791aa3501c1290be301c29996d44f210a Mon Sep 17 00:00:00 2001
From: Jay Nabonne <jay.nabonne@geoteric.com>
Date: Thu, 7 Feb 2019 09:08:08 +0000
Subject: [PATCH] Get initial tree control drag and drop working. Create a new
 type for tree item data, as it needs to be serialisable for drag and drop,
 and void* is not.

---
 src/qt/treectrl.cpp | 89 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 83 insertions(+), 6 deletions(-)

diff --git a/src/qt/treectrl.cpp b/src/qt/treectrl.cpp
index 4e12939906..6c792050a0 100644
--- a/src/qt/treectrl.cpp
+++ b/src/qt/treectrl.cpp
@@ -15,6 +15,34 @@
 
 namespace
 {
+    struct TreeItemDataQt
+    {
+        TreeItemDataQt() : data(NULL)
+        {
+        }
+        TreeItemDataQt(wxTreeItemData* data) : data(data)
+        {
+            if ( !registered )
+            {
+                qRegisterMetaTypeStreamOperators<TreeItemDataQt>("TreeItemDataQt");
+                registered = true;
+            }
+        }
+        wxTreeItemData *data;
+        static bool registered;
+    };
+    bool TreeItemDataQt::registered = false;
+    Q_DECLARE_METATYPE(TreeItemDataQt)
+
+    QDataStream &operator<<(QDataStream &out, const TreeItemDataQt &myObj)
+    {
+        return out;
+    }
+    QDataStream &operator>>(QDataStream &in, TreeItemDataQt &myObj)
+    {
+        return in;
+    }
+
     QTreeWidgetItem *wxQtConvertTreeItem(const wxTreeItemId &item)
     {
         return static_cast<QTreeWidgetItem*>(item.GetID());
@@ -36,6 +64,10 @@ namespace
             connect(this, &QTreeWidget::itemClicked, this, &wxQTreeWidget::OnItemClicked);
             connect(this, &QTreeWidget::itemCollapsed, this, &wxQTreeWidget::OnItemCollapsed);
             connect(this, &QTreeWidget::itemExpanded, this, &wxQTreeWidget::OnItemExpanded);
+
+            setDragEnabled(true);
+            viewport()->setAcceptDrops(true);
+            setDropIndicatorShown(true);
         }
 
     private:
@@ -112,6 +144,50 @@ namespace
             EmitEvent(expandedEvent);
 
         }
+
+        virtual void dragEnterEvent(QDragEnterEvent* event) wxOVERRIDE
+        {
+            wxEventType command = (event->mouseButtons() & Qt::RightButton)
+                ? wxEVT_TREE_BEGIN_RDRAG
+                : wxEVT_TREE_BEGIN_DRAG;
+
+
+            QTreeWidgetItem *hitItem = itemAt(event->pos());
+
+            wxTreeEvent tree_event(
+                command,
+                GetHandler(),
+                wxQtConvertTreeItem(hitItem)
+            );
+
+            tree_event.SetPoint(wxQtConvertPoint(event->pos()));
+
+            // Vetoed unless explicitly accepted.
+            tree_event.Veto();
+
+            EmitEvent(tree_event);
+
+            if ( tree_event.IsAllowed() )
+            {
+                event->accept();
+            }
+        }
+
+        virtual void dropEvent(QDropEvent* event) wxOVERRIDE
+        {
+            const wxPoint pos = wxQtConvertPoint(event->pos());
+            QTreeWidgetItem *hitItem = itemAt(event->pos());
+
+            wxTreeEvent tree_event(
+                wxEVT_TREE_END_DRAG,
+                GetHandler(),
+                wxQtConvertTreeItem(hitItem)
+            );
+
+            tree_event.SetPoint(wxQtConvertPoint(event->pos()));
+
+            EmitEvent(tree_event);
+        }
     };
 
 
@@ -138,7 +214,6 @@ namespace
             return QIcon::Selected;
         }
 
-        wxFAIL_MSG("Unspported tree icon state");
         return QIcon::Normal;
     }
 
@@ -229,8 +304,8 @@ wxTreeItemData *wxTreeCtrl::GetItemData(const wxTreeItemId& item) const
 
     QTreeWidgetItem* qTreeItem = wxQtConvertTreeItem(item);
     QVariant itemData = qTreeItem->data(0, Qt::UserRole);
-    void* value =  itemData.value<void *>();
-    return static_cast<wxTreeItemData*>(value);
+    TreeItemDataQt value = itemData.value<TreeItemDataQt>();
+    return value.data;
 }
 
 wxColour wxTreeCtrl::GetItemTextColour(const wxTreeItemId& item) const
@@ -239,7 +314,6 @@ wxColour wxTreeCtrl::GetItemTextColour(const wxTreeItemId& item) const
 
     QTreeWidgetItem* qTreeItem = wxQtConvertTreeItem(item);
     return wxQtConvertColour(qTreeItem->textColor(0));
-
 }
 
 wxColour wxTreeCtrl::GetItemBackgroundColour(const wxTreeItemId& item) const
@@ -291,7 +365,8 @@ void wxTreeCtrl::SetItemData(const wxTreeItemId& item, wxTreeItemData *data)
         data->SetId(item);
 
     QTreeWidgetItem *qTreeItem = wxQtConvertTreeItem(item);
-    qTreeItem->setData(0, Qt::UserRole, QVariant::fromValue(static_cast<void*>(data)));
+    TreeItemDataQt treeItemData(data);
+    qTreeItem->setData(0, Qt::UserRole, QVariant::fromValue(treeItemData));
 }
 
 void wxTreeCtrl::SetItemHasChildren(const wxTreeItemId& item, bool has)
@@ -829,7 +904,9 @@ wxTreeItemId wxTreeCtrl::DoInsertItem(const wxTreeItemId& parent,
 
     QTreeWidgetItem *newItem = new QTreeWidgetItem;
     newItem->setText(0, wxQtConvertString(text));
-    newItem->setData(0, Qt::UserRole, QVariant::fromValue(static_cast<void*>(data)));
+    TreeItemDataQt treeItemData(data);
+
+    newItem->setData(0, Qt::UserRole, QVariant::fromValue(treeItemData));
 
     if (pos == static_cast<size_t>(-1))
     {