Implement wxListCtrl::GetEditControl() for wxQt

To get access to the control used for editing items, we need to create
it ourselves, which involves defining our own factory for doing this,
but seems to be the only way of achieving our goal.

Closes https://github.com/wxWidgets/wxWidgets/pull/1204

include/wx/qt/listctrl.h

@@ -10,7 +10,7 @@
 
 #include "wx/textctrl.h"
 
-class QTreeWidget;
+class wxQtTreeWidget;
 class QTreeWidgetItem;
 
 class WXDLLIMPEXP_FWD_CORE wxImageList;
@@ -303,7 +303,7 @@ protected:
                       m_ownsImageListSmall,
                       m_ownsImageListState;
 private:
-    QTreeWidget *m_qtTreeWidget;
+    wxQtTreeWidget *m_qtTreeWidget;
 
     wxDECLARE_DYNAMIC_CLASS( wxListCtrl );
 };

src/qt/listctrl.cpp

@@ -13,6 +13,9 @@
 #endif
 
 #include <QtWidgets/QHeaderView>
+#include <QtWidgets/QTreeWidget>
+#include <QtWidgets/QItemDelegate>
+#include <QtWidgets/QItemEditorFactory>
 
 #ifndef WX_PRECOMP
     #include "wx/bitmap.h"
@@ -20,9 +23,105 @@
 
 #include "wx/listctrl.h"
 #include "wx/imaglist.h"
+#include "wx/recguard.h"
+
 #include "wx/qt/private/winevent.h"
 
-#include <QtWidgets/QTreeWidget>
+namespace
+{
+
+// wxQT Doesn't have a mechanism for "adopting" external widgets so we have to
+// create an instance of wxTextCtrl rather than adopting the control QT would
+// create.
+//
+// Unfortunately the factory is given an internal widget as the parent for
+// editor.
+//
+// To work around these issues we create a wxTextCtl parented by the wxListCtrl
+// then recalculate its position relative to the internal widget.
+class wxQtListTextCtrl : public wxTextCtrl
+{
+public:
+    wxQtListTextCtrl(wxWindow* parent, QWidget* actualParent)
+        : wxTextCtrl(parent, wxID_ANY, wxEmptyString,
+                     wxDefaultPosition, wxDefaultSize,
+                     wxNO_BORDER),
+        m_actualParent(actualParent),
+        m_moving(0)
+    {
+
+        Bind(wxEVT_MOVE, &wxQtListTextCtrl::onMove, this);
+    }
+
+    void onMove(wxMoveEvent &event)
+    {
+        // QWidget::move generates a QMoveEvent so we need to guard against
+        // reentrant calls.
+        wxRecursionGuard guard(m_moving);
+        if ( guard.IsInside() )
+        {
+            event.Skip();
+            return;
+        }
+
+        const QPoint eventPosition = wxQtConvertPoint(event.GetPosition());
+        const QPoint globalPosition  = m_actualParent->mapToGlobal(eventPosition);
+
+        // For some reason this always gives us the offset from the header info
+        // the internal control. So we need to treat this as an offset rather
+        // than a position.
+        QWidget* widget = GetHandle();
+        const QPoint offset = widget->mapFromGlobal(globalPosition);
+
+        widget->move(eventPosition + offset);
+    }
+
+private:
+    QWidget* m_actualParent;
+    wxRecursionGuardFlag m_moving;
+
+    wxDECLARE_NO_COPY_CLASS(wxQtListTextCtrl);
+};
+
+} // anonymous namespace
+
+
+// QT doesn't give us direct access to the editor within the QTreeWidget.
+// Instead, we'll supply a factory to create the widget for QT and keep track
+// of it ourselves.
+class wxQtItemEditorFactory : public QItemEditorFactory
+{
+public:
+    explicit wxQtItemEditorFactory(wxWindow* parent)
+        : m_parent(parent),
+          m_textCtrl(NULL)
+    {
+    }
+
+    QWidget* createEditor(int WXUNUSED(userType), QWidget* parent) const wxOVERRIDE
+    {
+        m_textCtrl = new wxQtListTextCtrl(m_parent, parent);
+        m_textCtrl->SetFocus();
+        return m_textCtrl->GetHandle();
+    }
+
+    wxTextCtrl* GetEditControl()
+    {
+        return m_textCtrl;
+    }
+
+    void ClearEditor()
+    {
+        delete m_textCtrl;
+        m_textCtrl = NULL;
+    }
+
+private:
+    wxWindow* m_parent;
+    mutable wxTextCtrl* m_textCtrl;
+
+    wxDECLARE_NO_COPY_CLASS(wxQtItemEditorFactory);
+};
 
 class wxQtTreeWidget : public wxQtEventSignalHandler< QTreeWidget, wxListCtrl >
 {
@@ -31,18 +130,41 @@ public:
 
     void EmitListEvent(wxEventType typ, QTreeWidgetItem *qitem, int column) const;
 
+    void closeEditor(QWidget *editor, QAbstractItemDelegate::EndEditHint hint) wxOVERRIDE
+    {
+        QTreeWidget::closeEditor(editor, hint);
+        m_editorFactory.ClearEditor();
+    }
+
+    wxTextCtrl *GetEditControl()
+    {
+        return m_editorFactory.GetEditControl();
+    }
+
 private:
     void itemClicked(QTreeWidgetItem * item, int column);
     void itemActivated(QTreeWidgetItem * item, int column);
     void itemPressed(QTreeWidgetItem * item, int column);
+
+    void ChangeEditorFactory()
+    {
+        QItemDelegate *qItemDelegate = static_cast<QItemDelegate*>(itemDelegate());
+        qItemDelegate->itemEditorFactory();
+        qItemDelegate->setItemEditorFactory(&m_editorFactory);
+    }
+
+    wxQtItemEditorFactory m_editorFactory;
 };
 
 wxQtTreeWidget::wxQtTreeWidget( wxWindow *parent, wxListCtrl *handler )
-    : wxQtEventSignalHandler< QTreeWidget, wxListCtrl >( parent, handler )
+    : wxQtEventSignalHandler< QTreeWidget, wxListCtrl >( parent, handler ),
+      m_editorFactory(handler)
 {
     connect(this, &QTreeWidget::itemClicked, this, &wxQtTreeWidget::itemClicked);
     connect(this, &QTreeWidget::itemPressed, this, &wxQtTreeWidget::itemPressed);
     connect(this, &QTreeWidget::itemActivated, this, &wxQtTreeWidget::itemActivated);
+
+    ChangeEditorFactory();
 }
 
 void wxQtTreeWidget::EmitListEvent(wxEventType typ, QTreeWidgetItem *qitem, int column) const
@@ -251,7 +373,7 @@ wxRect wxListCtrl::GetViewRect() const
 
 wxTextCtrl* wxListCtrl::GetEditControl() const
 {
-    return NULL;
+    return m_qtTreeWidget->GetEditControl();
 }
 
 QTreeWidgetItem *wxListCtrl::QtGetItem(int id) const