create separate class for radiobutton icon

components/radiobutton_internal.cpp

@@ -0,0 +1,21 @@
+#include "radiobutton_internal.h"
+#include <QPainter>
+
+RadioButtonIcon::RadioButtonIcon(QWidget *parent)
+    : QWidget(parent)
+{
+}
+
+RadioButtonIcon::~RadioButtonIcon()
+{
+}
+
+void RadioButtonIcon::paintEvent(QPaintEvent *event)
+{
+    Q_UNUSED(event)
+
+    QPainter painter(this);
+
+    painter.setPen(Qt::red);
+    painter.drawRect(rect());
+}

components/radiobutton_internal.h

@@ -0,0 +1,21 @@
+#ifndef RADIOBUTTON_INTERNAL_H
+#define RADIOBUTTON_INTERNAL_H
+
+#include <QWidget>
+
+class RadioButtonIcon : public QWidget
+{
+    Q_OBJECT
+
+public:
+    RadioButtonIcon(QWidget *parent = 0);
+    ~RadioButtonIcon();
+
+protected:
+    void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
+
+private:
+    Q_DISABLE_COPY(RadioButtonIcon)
+};
+
+#endif // RADIOBUTTON_INTERNAL_H