add slider example for vertical slider

components/slider.cpp

@@ -1,10 +1,43 @@
+#include <QPainter>
 #include "slider.h"
 
-Slider::Slider(QWidget *parent)
+Handle::Handle(QWidget *parent)
     : QWidget(parent)
 {
 }
 
+Handle::~Handle()
+{
+}
+
+void Handle::paintEvent(QPaintEvent *event)
+{
+    QPainter painter(this);
+    QPen pen;
+    pen.setColor(Qt::black);
+    pen.setWidth(1);
+    painter.setPen(pen);
+    painter.drawRect(rect().adjusted(0, 0, -1, -1));
+
+    QWidget::paintEvent(event);
+}
+
+Slider::Slider(QWidget *parent)
+    : QWidget(parent),
+      _handle(new Handle(this))
+{
+    _handle->setGeometry(10, 10, 30, 30);
+}
+
 Slider::~Slider()
 {
 }
+
+void Slider::paintEvent(QPaintEvent *event)
+{
+    QPainter painter(this);
+
+    painter.drawRect(rect().adjusted(0, 0, -1, -1));
+
+    QWidget::paintEvent(event);
+}

components/slider.h

@@ -3,6 +3,18 @@
 
 #include <QWidget>
 
+class Handle : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit Handle(QWidget *parent = 0);
+    ~Handle();
+
+protected:
+    void paintEvent(QPaintEvent *event);
+};
+
 class Slider : public QWidget
 {
     Q_OBJECT
@@ -10,6 +22,12 @@ class Slider : public QWidget
 public:
     explicit Slider(QWidget *parent = 0);
     ~Slider();
+
+protected:
+    void paintEvent(QPaintEvent *event);
+
+private:
+    Handle *const _handle;
 };
 
 #endif // SLIDER_H

examples/sliderexamples.cpp

@@ -28,6 +28,25 @@ SliderExamples::SliderExamples(QWidget *parent)
 
         mainLayout->addWidget(frame);
     }
+    {
+        QWidget *widget = new QWidget;
+        QVBoxLayout *layout = new QVBoxLayout;
+
+        widget->setLayout(layout);
+
+        Slider *slider = new Slider;
+
+        ExampleView *view = new ExampleView;
+        view->setWidget(slider);
+
+        Frame *frame = new Frame;
+        frame->setCodeSnippet(
+            "---"
+        );
+        frame->setWidget(view);
+
+        mainLayout->addWidget(frame);
+    }
 }
 
 SliderExamples::~SliderExamples()