fix missing showEvent in AVForm

src/widget/form/settings/avform.cpp

@@ -135,6 +135,11 @@ void AVForm::hideEvent(QHideEvent *)
     bodyUI->CamVideoSurface->setSource(nullptr);
 }
 
+void AVForm::showEvent(QShowEvent *)
+{
+    bodyUI->CamVideoSurface->setSource(Camera::getInstance());
+}
+
 void AVForm::getAudioInDevices()
 {
     QString settingsInDev = Settings::getInstance().getInDev();

src/widget/form/settings/avform.h

@@ -59,6 +59,7 @@ private slots:
     void onResProbingFinished(QList<QSize> res);
 
     virtual void hideEvent(QHideEvent*);
+    virtual void showEvent(QShowEvent*);
 
 private:
     Ui::AVSettings *bodyUI;