Fix crash when deleting layout items

nyalldawson · nyalldawson · commit fe13c0e81b74 · 2018-01-20T06:11:11.000+10:00
Fixes #17876, #17770
diff --git a/src/gui/layout/qgslayoutitemwidget.cpp b/src/gui/layout/qgslayoutitemwidget.cpp
@@ -190,6 +190,9 @@ QgsLayoutAtlas *QgsLayoutItemBaseWidget::layoutAtlas() const
 
 void QgsLayoutItemPropertiesWidget::updateVariables()
 {
+  if ( !mItem )
+    return;
+
   QgsExpressionContext context = mItem->createExpressionContext();
   mVariableEditor->setContext( &context );
   int editableIndex = context.indexOfScope( tr( "Layout Item" ) );
@@ -295,8 +298,11 @@ void QgsLayoutItemPropertiesWidget::setItem( QgsLayoutItem *item )
     disconnect( mItem, &QgsLayoutObject::changed, this, &QgsLayoutItemPropertiesWidget::setValuesForGuiNonPositionElements );
   }
   mItem = item;
-  connect( mItem, &QgsLayoutItem::sizePositionChanged, this, &QgsLayoutItemPropertiesWidget::setValuesForGuiPositionElements );
-  connect( mItem, &QgsLayoutObject::changed, this, &QgsLayoutItemPropertiesWidget::setValuesForGuiNonPositionElements );
+  if ( mItem )
+  {
+    connect( mItem, &QgsLayoutItem::sizePositionChanged, this, &QgsLayoutItemPropertiesWidget::setValuesForGuiPositionElements );
+    connect( mItem, &QgsLayoutObject::changed, this, &QgsLayoutItemPropertiesWidget::setValuesForGuiNonPositionElements );
+  }
 
   setValuesForGuiElements();
 }
@@ -329,6 +335,9 @@ void QgsLayoutItemPropertiesWidget::mBackgroundColorButton_colorChanged( const Q
 
 void QgsLayoutItemPropertiesWidget::changeItemPosition()
 {
+  if ( !mItem )
+    return;
+
   mItem->layout()->undoStack()->beginCommand( mItem, tr( "Move Item" ), QgsLayoutItem::UndoIncrementalMove );
 
   QgsLayoutPoint point( mXPosSpin->value(), mYPosSpin->value(), mPosUnitsComboBox->unit() );
@@ -339,13 +348,19 @@ void QgsLayoutItemPropertiesWidget::changeItemPosition()
 
 void QgsLayoutItemPropertiesWidget::changeItemReference( QgsLayoutItem::ReferencePoint point )
 {
+  if ( !mItem )
+    return;
+
   mItem->layout()->undoStack()->beginCommand( mItem, tr( "Change Item Reference" ) );
   mItem->setReferencePoint( point );
   mItem->layout()->undoStack()->endCommand();
 }
 
 void QgsLayoutItemPropertiesWidget::changeItemSize()
 {
+  if ( !mItem )
+    return;
+
   mItem->layout()->undoStack()->beginCommand( mItem, tr( "Resize Item" ), QgsLayoutItem::UndoIncrementalResize );
 
   QgsLayoutSize size( mWidthSpin->value(), mHeightSpin->value(), mSizeUnitsComboBox->unit() );
@@ -356,6 +371,9 @@ void QgsLayoutItemPropertiesWidget::changeItemSize()
 
 void QgsLayoutItemPropertiesWidget::variablesChanged()
 {
+  if ( !mItem )
+    return;
+
   QgsExpressionContextUtils::setLayoutItemVariables( mItem, mVariableEditor->variablesInActiveScope() );
 }
 
diff --git a/src/gui/layout/qgslayoutitemwidget.h b/src/gui/layout/qgslayoutitemwidget.h
@@ -265,7 +265,7 @@ class GUI_EXPORT QgsLayoutItemPropertiesWidget: public QWidget, private Ui::QgsL
 
   private:
 
-    QgsLayoutItem *mItem = nullptr;
+    QPointer< QgsLayoutItem > mItem;
     QgsLayoutConfigObject *mConfigObject = nullptr;
 
     bool mFreezeXPosSpin = false;
