QmlDesigner: Override shortcuts in text editor

There are a couple of known shortcuts that we have to override
in the text editor. We install an event filter and handle
the shortcut override event for the keys in question.

Change-Id: Icb5483b19e2202d85e99d24c20d05097aaa33da6
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/texteditor/texteditorwidget.cpp

@@ -34,8 +34,12 @@
 
 #include <utils/fileutils.h>
 
+#include <QEvent>
 #include <QVBoxLayout>
 
+#include <vector>
+#include <algorithm>
+
 namespace QmlDesigner {
 
 TextEditorWidget::TextEditorWidget(TextEditorView *textEditorView) : QWidget()
@@ -64,6 +68,7 @@ void TextEditorWidget::setTextEditor(TextEditor::BaseTextEditor *textEditor) {
 
     connect(textEditor->editorWidget(), &QPlainTextEdit::cursorPositionChanged,
             &m_updateSelectionTimer, static_cast<void (QTimer::*)()>(&QTimer::start));
+    textEditor->editorWidget()->installEventFilter(this);
 }
 
 QString TextEditorWidget::contextHelpId() const
@@ -136,4 +141,18 @@ int TextEditorWidget::currentLine() const
     return -1;
 }
 
+bool TextEditorWidget::eventFilter( QObject *, QEvent *event)
+{
+    static std::vector<int> overrideKeys = { Qt::Key_Delete, Qt::Key_Backspace, Qt::Key_Left, Qt::Key_Right, Qt::Key_Up, Qt::Key_Down };
+    if (event->type() == QEvent::ShortcutOverride) {
+        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
+        if (std::find(overrideKeys.begin(), overrideKeys.end(), keyEvent->key()) != overrideKeys.end()) {
+            keyEvent->accept();
+            return true;
+        }
+    }
+    return false;
+}
+
+
 } // namespace QmlDesigner

src/plugins/qmldesigner/components/texteditor/texteditorwidget.h

@@ -58,6 +58,9 @@ public:
     void clearStatusBar();
 
     int currentLine() const;
+protected:
+    bool eventFilter(QObject *object, QEvent *event) override;
+
 private:
     void updateSelectionByCursorPosition();