Avoid loss of text in code editors when certain modifiers are pressed

These are triggered when a InputMethod event is sent to the widget. There's upstream discussion at https://sourceforge.net/p/scintilla/bugs/1913/ and the fix was added to QScintilla version 2.13.3 As the loss of text is an extreme risk, just disable input method handling in these widgets on affected versions entirely. Fixes #52459
qgis · Apr 4, 2023 · 7886f7e · 7886f7e
1 parent cb09be0
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diff --git a/python/gui/auto_generated/codeeditors/qgscodeeditor.sip.in b/python/gui/auto_generated/codeeditors/qgscodeeditor.sip.in
@@ -443,6 +443,8 @@ Returns ``True`` if a ``font`` is a fixed pitch font.
 
     virtual void contextMenuEvent( QContextMenuEvent *event );
 
+    virtual bool eventFilter( QObject *watched, QEvent *event );
+
 
     virtual void initializeLexer();
 %Docstring

diff --git a/src/gui/codeeditors/qgscodeeditor.cpp b/src/gui/codeeditors/qgscodeeditor.cpp
@@ -135,6 +135,10 @@ QgsCodeEditor::QgsCodeEditor( QWidget *parent, const QString &title, bool foldin
       break;
     }
   }
+
+#if QSCINTILLA_VERSION < 0x020d03
+  installEventFilter( this );
+#endif
 }
 
 // Workaround a bug in QScintilla 2.8.X
@@ -240,6 +244,21 @@ void QgsCodeEditor::contextMenuEvent( QContextMenuEvent *event )
   menu->exec( mapToGlobal( event->pos() ) );
 }
 
+bool QgsCodeEditor::eventFilter( QObject *watched, QEvent *event )
+{
+#if QSCINTILLA_VERSION < 0x020d03
+  if ( watched == this && event->type() == QEvent::InputMethod )
+  {
+    // swallow input method events, which cause loss of selected text.
+    // See https://sourceforge.net/p/scintilla/bugs/1913/ , which was ported to QScintilla
+    // in version 2.13.3
+    return true;
+  }
+#endif
+
+  return QsciScintilla::eventFilter( watched, event );
+}
+
 void QgsCodeEditor::initializeLexer()
 {
 

diff --git a/src/gui/codeeditors/qgscodeeditor.h b/src/gui/codeeditors/qgscodeeditor.h
@@ -456,6 +456,7 @@ class GUI_EXPORT QgsCodeEditor : public QsciScintilla
     void focusOutEvent( QFocusEvent *event ) override;
     void keyPressEvent( QKeyEvent *event ) override;
     void contextMenuEvent( QContextMenuEvent *event ) override;
+    bool eventFilter( QObject *watched, QEvent *event ) override;
 
     /**
      * Called when the dialect specific code lexer needs to be initialized (or reinitialized).