implement toggle state machine

components/toggle.cpp

@@ -1,9 +1,12 @@
 #include "toggle.h"
 #include <QPainter>
+#include <QState>
+#include <QEventTransition>
 #include "toggle_p.h"
 
 TogglePrivate::TogglePrivate(Toggle *q)
     : q_ptr(q),
+      thumb(new Thumb(q)),
       orientation(Qt::Horizontal)
 {
 }
@@ -13,6 +16,37 @@ void TogglePrivate::init()
     Q_Q(Toggle);
 
     q->setSizePolicy(QSizePolicy::Maximum, QSizePolicy::Maximum);
+
+    QState *offState = new QState;
+    QState *onState = new QState;
+
+    machine.addState(offState);
+    machine.addState(onState);
+
+    machine.setInitialState(offState);
+
+    QEventTransition *transition;
+
+    transition = new QEventTransition(q, QEvent::MouseButtonPress);
+    transition->setTargetState(onState);
+    offState->addTransition(transition);
+
+    transition = new QEventTransition(q, QEvent::MouseButtonDblClick);
+    transition->setTargetState(onState);
+    offState->addTransition(transition);
+
+    transition = new QEventTransition(q, QEvent::MouseButtonPress);
+    transition->setTargetState(offState);
+    onState->addTransition(transition);
+
+    transition = new QEventTransition(q, QEvent::MouseButtonDblClick);
+    transition->setTargetState(offState);
+    onState->addTransition(transition);
+
+    offState->assignProperty(thumb, "shift", 0);
+    onState->assignProperty(thumb, "shift", 1);
+
+    machine.start();
 }
 
 Toggle::Toggle(QWidget *parent)
@@ -35,6 +69,13 @@ QSize Toggle::sizeHint() const
         : QSize(48, 64);
 }
 
+Qt::Orientation Toggle::orientation() const
+{
+    Q_D(const Toggle);
+
+    return d->orientation;
+}
+
 void Toggle::setOrientation(Qt::Orientation orientation)
 {
     Q_D(Toggle);

components/toggle.h

@@ -15,6 +15,7 @@ public:
 
     QSize sizeHint() const;
 
+    Qt::Orientation orientation() const;
     void setOrientation(Qt::Orientation orientation) Q_DECL_OVERRIDE;
 
 protected:

components/toggle_internal.cpp

@@ -1,11 +1,64 @@
+#include <QPainter>
+#include <QEvent>
 #include "toggle_internal.h"
 #include "toggle.h"
 
 Thumb::Thumb(Toggle *parent)
-    : QWidget(parent)
+    : QWidget(parent),
+      _toggle(parent),
+      _shift(0),
+      _offset(0)
 {
+    parent->installEventFilter(this);
 }
 
 Thumb::~Thumb()
 {
 }
+
+void Thumb::setShift(qreal shift)
+{
+    if (_shift == shift)
+        return;
+
+    _shift = shift;
+
+    const QSize s(Qt::Horizontal == _toggle->orientation()
+            ? size() : size().transposed());
+
+    _offset = shift*static_cast<qreal>(s.width()-s.height());
+    update();
+}
+
+bool Thumb::eventFilter(QObject *obj, QEvent *event)
+{
+    const QEvent::Type type = event->type();
+    if (QEvent::Resize == type || QEvent::Move == type) {
+        setGeometry(parentWidget()->rect().adjusted(8, 8, -8, -8));
+    } //else if (QEvent::MouseButtonRelease == type) {
+        //return true;
+    //}
+    return QWidget::eventFilter(obj, event);
+}
+
+void Thumb::paintEvent(QPaintEvent *event)
+{
+    Q_UNUSED(event)
+
+    QPainter painter(this);
+    painter.setRenderHint(QPainter::Antialiasing);
+
+    QBrush brush;
+    brush.setStyle(Qt::SolidPattern);
+    brush.setColor(Qt::white);
+    painter.setBrush(brush);
+    painter.setPen(Qt::NoPen);
+
+    if (Qt::Horizontal == _toggle->orientation()) {
+        const int s = height()-10;
+        painter.drawEllipse(5+_offset, 5, s, s);
+    } else {
+        const int s = width()-10;
+        painter.drawEllipse(5, 5+_offset, s, s);
+    }
+}

components/toggle_internal.h

@@ -9,12 +9,25 @@ class Thumb : public QWidget
 {
     Q_OBJECT
 
+    Q_PROPERTY(qreal shift WRITE setShift READ shift)
+
 public:
     Thumb(Toggle *parent);
     ~Thumb();
 
+    void setShift(qreal shift);
+    inline qreal shift() const { return _shift; }
+
+protected:
+    bool eventFilter(QObject *obj, QEvent *event) Q_DECL_OVERRIDE;
+    void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
+
 private:
     Q_DISABLE_COPY(Thumb)
+
+    Toggle *const _toggle;
+    qreal _shift;
+    int _offset;
 };
 
 #endif // TOGGLE_INTERNAL_H

components/toggle_p.h

@@ -1,6 +1,7 @@
 #ifndef TOGGLE_P_H
 #define TOGGLE_P_H
 
+#include <QStateMachine>
 #include "toggle_internal.h"
 
 class TogglePrivate
@@ -14,6 +15,8 @@ public:
     void init();
 
     Toggle *const q_ptr;
+    Thumb  *const thumb;
+    QStateMachine machine;
     Qt::Orientation orientation;
 };