From bd5a9adfeaa5e3b3c3d2458a070c2022476da7fe Mon Sep 17 00:00:00 2001
From: laserpants <johannes@isomorphic.co>
Date: Wed, 23 Mar 2016 08:35:41 +0300
Subject: [PATCH] implement slider functionality

---
 components/slider.cpp       | 58 ++++++++++++++++++++++++++++++++++---
 components/slider.h         | 22 ++++++++++++--
 examples/sliderexamples.cpp |  6 ++--
 3 files changed, 78 insertions(+), 8 deletions(-)

diff --git a/components/slider.cpp b/components/slider.cpp
index 446dd28..6b75ed4 100644
--- a/components/slider.cpp
+++ b/components/slider.cpp
@@ -1,8 +1,11 @@
 #include <QPainter>
+#include <QDebug>
+#include <QMouseEvent>
 #include "slider.h"
 
-Handle::Handle(QWidget *parent)
-    : QWidget(parent)
+Handle::Handle(Slider *slider)
+    : QWidget(slider),
+      _slider(slider)
 {
 }
 
@@ -22,11 +25,35 @@ void Handle::paintEvent(QPaintEvent *event)
     QWidget::paintEvent(event);
 }
 
+void Handle::mousePressEvent(QMouseEvent *event)
+{
+    _eventPos = event->globalPos();
+    _offset = pos();
+}
+
+void Handle::mouseReleaseEvent(QMouseEvent *event)
+{
+    Q_UNUSED(event)
+}
+
+void Handle::mouseMoveEvent(QMouseEvent *event)
+{
+    Q_UNUSED(event)
+
+    QWidget *container = parentWidget();
+    const QPoint d = _offset + event->globalPos() - _eventPos;
+    const QSize  s = sizeHint();
+    QRect r(_slider->orientation() == Qt::Horizontal
+        ? QPoint(qBound(0, d.x(), container->width()-s.width()), container->height()/2-s.height()/2)
+        : QPoint(container->width()/2-s.width()/2, qBound(0, d.y(), container->height()-s.height())), s);
+    setGeometry(r);
+}
+
 Slider::Slider(QWidget *parent)
     : QWidget(parent),
-      _handle(new Handle(this))
+      _handle(new Handle(this)),
+      _orientation(Qt::Horizontal)
 {
-    _handle->setGeometry(10, 10, 30, 30);
 }
 
 Slider::~Slider()
@@ -37,7 +64,30 @@ void Slider::paintEvent(QPaintEvent *event)
 {
     QPainter painter(this);
 
+    const int x = width()/2;
+    const int y = height()/2;
+
+    QRect r = Qt::Vertical == _orientation
+            ? QRect(x-2, 0, 4, height())
+            : QRect(0, y-2, width(), 4);
+
+    QBrush brush;
+    brush.setStyle(Qt::SolidPattern);
+    brush.setColor(QColor(0, 0, 0));
+    painter.fillRect(r, brush);
+
     painter.drawRect(rect().adjusted(0, 0, -1, -1));
 
     QWidget::paintEvent(event);
 }
+
+void Slider::mousePressEvent(QMouseEvent *event)
+{
+    const QSize s = _handle->sizeHint();
+
+    _handle->setGeometry(QRect(Qt::Horizontal == _orientation
+        ? QPoint(event->pos().x()-s.width()/2, height()/2-s.height()/2)
+        : QPoint(width()/2-s.width()/2, event->pos().y()-s.height()/2), s));
+
+    QWidget::mousePressEvent(event);
+}
diff --git a/components/slider.h b/components/slider.h
index 32aeb99..c92139a 100644
--- a/components/slider.h
+++ b/components/slider.h
@@ -2,17 +2,30 @@
 #define SLIDER_H
 
 #include <QWidget>
+#include <QPoint>
+
+class Slider;
 
 class Handle : public QWidget
 {
     Q_OBJECT
 
 public:
-    explicit Handle(QWidget *parent = 0);
+    explicit Handle(Slider *slider);
     ~Handle();
 
+    inline QSize sizeHint() const { return QSize(16, 16); }
+
 protected:
     void paintEvent(QPaintEvent *event);
+    void mousePressEvent(QMouseEvent *event);
+    void mouseReleaseEvent(QMouseEvent *event);
+    void mouseMoveEvent(QMouseEvent *event);
+
+private:
+    Slider *const _slider;
+    QPoint        _eventPos;
+    QPoint        _offset;
 };
 
 class Slider : public QWidget
@@ -23,11 +36,16 @@ public:
     explicit Slider(QWidget *parent = 0);
     ~Slider();
 
+    inline void setOrientation(Qt::Orientation orientation) { _orientation = orientation; }
+    inline Qt::Orientation orientation() const { return _orientation; }
+
 protected:
     void paintEvent(QPaintEvent *event);
+    void mousePressEvent(QMouseEvent *event);
 
 private:
-    Handle *const _handle;
+    Handle   *const _handle;
+    Qt::Orientation _orientation;
 };
 
 #endif // SLIDER_H
diff --git a/examples/sliderexamples.cpp b/examples/sliderexamples.cpp
index 87e4e1e..45b57b3 100644
--- a/examples/sliderexamples.cpp
+++ b/examples/sliderexamples.cpp
@@ -22,7 +22,7 @@ SliderExamples::SliderExamples(QWidget *parent)
 
         Frame *frame = new Frame;
         frame->setCodeSnippet(
-            "---"
+            "Slider *slider = new Slider;"
         );
         frame->setWidget(view);
 
@@ -35,13 +35,15 @@ SliderExamples::SliderExamples(QWidget *parent)
         widget->setLayout(layout);
 
         Slider *slider = new Slider;
+        slider->setOrientation(Qt::Vertical);
 
         ExampleView *view = new ExampleView;
         view->setWidget(slider);
 
         Frame *frame = new Frame;
         frame->setCodeSnippet(
-            "---"
+            "Slider *slider = new Slider;\n"
+            "slider->setOrientation(Qt::Vertical);"
         );
         frame->setWidget(view);