From 81eab3f1dbe670af7be448f4ec438f2a25603e0e Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Sat, 3 Sep 2022 16:59:27 +0200
Subject: [PATCH] More safety against deleting view in view widget

---
 src/laybasic/laybasic/layLayoutViewBase.h | 13 ++++---
 src/laybasic/laybasic/layPlugin.h         |  8 +++++
 src/layview/layview/layLayoutView_qt.cc   | 41 ++++++++++++++++++-----
 src/layview/layview/layLayoutView_qt.h    |  4 +++
 4 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/src/laybasic/laybasic/layLayoutViewBase.h b/src/laybasic/laybasic/layLayoutViewBase.h
index 0ed2f28cf..b50a8d412 100644
--- a/src/laybasic/laybasic/layLayoutViewBase.h
+++ b/src/laybasic/laybasic/layLayoutViewBase.h
@@ -2661,6 +2661,14 @@ public:
    */
   void unregister_plugin (lay::Plugin *pi);
 
+  /**
+   *  @brief Gets the options the view was created with
+   */
+  unsigned int options () const
+  {
+    return m_options;
+  }
+
 private:
   //  event handlers used to connect to the layout object's events
   void signal_hier_changed ();
@@ -2828,11 +2836,6 @@ private:
   void merge_dither_pattern (lay::LayerPropertiesList &props);
 
 protected:
-  unsigned int options () const
-  {
-    return m_options;
-  }
-
   lay::Plugin *active_plugin () const
   {
     return mp_active_plugin;
diff --git a/src/laybasic/laybasic/layPlugin.h b/src/laybasic/laybasic/layPlugin.h
index 7fb074a42..a8f57bcd7 100644
--- a/src/laybasic/laybasic/layPlugin.h
+++ b/src/laybasic/laybasic/layPlugin.h
@@ -785,6 +785,14 @@ public:
     return mp_plugin_declaration;
   }
 
+  /**
+   *  @brief Gets the plugin parent
+   */
+  Plugin *plugin_parent ()
+  {
+    return mp_parent;
+  }
+
   /**
    *  @brief Associate a service with the plugin declaration for that service (setter)
    *
diff --git a/src/layview/layview/layLayoutView_qt.cc b/src/layview/layview/layLayoutView_qt.cc
index e5bb2b62f..26bc8a78e 100644
--- a/src/layview/layview/layLayoutView_qt.cc
+++ b/src/layview/layview/layLayoutView_qt.cc
@@ -109,19 +109,35 @@ LayoutViewWidget::LayoutViewWidget (lay::LayoutView *source, db::Manager *mgr, b
 
 LayoutViewWidget::~LayoutViewWidget ()
 {
-  delete mp_view;
+  lay::LayoutView *view = mp_view;
   mp_view = 0;
+  delete view;
+}
+
+void
+LayoutViewWidget::view_deleted (lay::LayoutView *view)
+{
+  if (view != mp_view) {
+    return;
+  }
+
+  //  creates a new view so the view is never invalid
+  mp_view = new LayoutView (view->manager (), view->is_editable (), view->plugin_parent (), this, view->options ());
 }
 
 QSize
 LayoutViewWidget::sizeHint () const
 {
-  return mp_view->size_hint ();
+  return mp_view ? mp_view->size_hint () : QFrame::sizeHint ();
 }
 
 bool
 LayoutViewWidget::eventFilter(QObject *obj, QEvent *event)
 {
+  if (! mp_view) {
+    return QFrame::eventFilter (obj, event);
+  }
+
   bool taken = false;
   bool res = mp_view->event_filter (obj, event, taken);
   if (taken) {
@@ -133,37 +149,41 @@ LayoutViewWidget::eventFilter(QObject *obj, QEvent *event)
 
 void LayoutViewWidget::showEvent (QShowEvent *)
 {
-  mp_view->show_event ();
+  if (mp_view) {
+    mp_view->show_event ();
+  }
 }
 
 void LayoutViewWidget::hideEvent (QHideEvent *)
 {
-  mp_view->hide_event ();
+  if (mp_view) {
+    mp_view->hide_event ();
+  }
 }
 
 QWidget *LayoutViewWidget::layer_control_frame ()
 {
-  return view ()->layer_control_frame ();
+  return !mp_view ? 0 : mp_view->layer_control_frame ();
 }
 
 QWidget *LayoutViewWidget::hierarchy_control_frame ()
 {
-  return view ()->hierarchy_control_frame ();
+  return !mp_view ? 0 : mp_view->hierarchy_control_frame ();
 }
 
 QWidget *LayoutViewWidget::libraries_frame ()
 {
-  return view ()->libraries_frame ();
+  return !mp_view ? 0 : mp_view->libraries_frame ();
 }
 
 QWidget *LayoutViewWidget::bookmarks_frame ()
 {
-  return view ()->bookmarks_frame ();
+  return !mp_view ? 0 : mp_view->bookmarks_frame ();
 }
 
 QWidget *LayoutViewWidget::editor_options_frame ()
 {
-  return view ()->editor_options_frame ();
+  return !mp_view ? 0 : mp_view->editor_options_frame ();
 }
 
 // -------------------------------------------------------------
@@ -458,6 +478,9 @@ LayoutView::init_ui ()
 LayoutView::~LayoutView ()
 {
   close ();
+  if (mp_widget) {
+    mp_widget->view_deleted (this);
+  }
 }
 
 QWidget *LayoutView::widget ()
diff --git a/src/layview/layview/layLayoutView_qt.h b/src/layview/layview/layLayoutView_qt.h
index c1d7faaee..1c3c4ca4b 100644
--- a/src/layview/layview/layLayoutView_qt.h
+++ b/src/layview/layview/layLayoutView_qt.h
@@ -799,6 +799,10 @@ signals:
   void layer_order_changed ();
 
 private:
+  friend class LayoutView;
+
+  void view_deleted (lay::LayoutView *view);
+
   LayoutView *mp_view;
 };