Qt Designer plugin: Add a dummy class for querying properties

Add a lightweight "fake" QWebEngineView class that is returned when Qt Designer
queries the default property values by calling
QDesignerCustomWidgetInterface::createWidget() with 0 parent,
preventing crashes during QWebEngine initialization.

Task-number: QTBUG-53984
Change-Id: Iced64b7d8af4c958fe7e29fa2f64bb9b681fbab2
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

2 files changed, 37 insertions, 1 deletions

diff --git a/src/plugins/qwebengineview/qwebengineview_plugin.cpp b/src/plugins/qwebengineview/qwebengineview_plugin.cpp
index 2d331571b..c885816c5 100644
--- a/src/plugins/qwebengineview/qwebengineview_plugin.cpp
+++ b/src/plugins/qwebengineview/qwebengineview_plugin.cpp
@@ -91,7 +91,9 @@ bool QWebEngineViewPlugin::isContainer() const
 
 QWidget *QWebEngineViewPlugin::createWidget(QWidget *parent)
 {
-    return new QWebEngineView(parent);
+    if (parent)
+        return new QWebEngineView(parent);
+    return new fake::QWebEngineView;
 }
 
 bool QWebEngineViewPlugin::isInitialized() const
diff --git a/src/plugins/qwebengineview/qwebengineview_plugin.h b/src/plugins/qwebengineview/qwebengineview_plugin.h
index 8fa94625c..7c6f02e2a 100644
--- a/src/plugins/qwebengineview/qwebengineview_plugin.h
+++ b/src/plugins/qwebengineview/qwebengineview_plugin.h
@@ -38,9 +38,43 @@
 #define QWEBENGINEVIEW_PLUGIN_H
 
 #include <QtUiPlugin/QDesignerCustomWidgetInterface>
+#include <QtWidgets/QWidget>
+#include <QtGui/QIcon>
+#include <QtCore/QUrl>
 
 QT_BEGIN_NAMESPACE
 
+namespace fake {
+// A lightweight "fake" QWebEngineView class that is returned when Qt Designer
+// queries the default property values by calling
+// QDesignerCustomWidgetInterface::createWidget() with 0 parent, preventing
+// crashes during QWebEngine initialization (QTBUG-53984).
+// The property list needs to be kept in sync with QWebEngineView.
+class QWebEngineView : public QWidget {
+    Q_OBJECT
+    Q_PROPERTY(QString title READ title)
+    Q_PROPERTY(QUrl url READ url WRITE setUrl) // Designable
+    Q_PROPERTY(QUrl iconUrl READ iconUrl)
+    Q_PROPERTY(QIcon icon READ icon)
+    Q_PROPERTY(QString selectedText READ selectedText)
+    Q_PROPERTY(bool hasSelection READ hasSelection)
+    Q_PROPERTY(qreal zoomFactor READ zoomFactor WRITE setZoomFactor) // Designable
+
+public:
+    explicit QWebEngineView(QWidget *parent = Q_NULLPTR) : QWidget(parent) {}
+
+    QString title() const { return QString(); }
+    QUrl url() const { return QUrl(); }
+    void setUrl(const QUrl &) {}
+    QUrl iconUrl() const { return QUrl(); }
+    QIcon icon() const { return QIcon(); }
+    QString selectedText() { return QString(); }
+    bool hasSelection() { return false; }
+    qreal zoomFactor() const { return 1; }
+    void setZoomFactor(qreal) {}
+};
+} // namespace fake
+
 class QWebEngineViewPlugin: public QObject, public QDesignerCustomWidgetInterface
 {
     Q_OBJECT