only move knob when drawing along the arc

examples/iotdashboard/LightDisplay.cpp

@@ -6,8 +6,11 @@
 #include "LightDisplay.h"
 #include "Skin.h"
 
+#include <QskArcMetrics.h>
 #include <QskEvent.h>
 
+#include <QtMath>
+
 QSK_SUBCONTROL( LightDisplay, Panel )
 QSK_SUBCONTROL( LightDisplay, Groove )
 QSK_SUBCONTROL( LightDisplay, ColdAndWarmArc )
@@ -88,11 +91,17 @@ void LightDisplay::mouseMoveEvent( QMouseEvent* event )
     if ( !isPressed() )
         return;
 
-    // ### check if arc contains the position
-
     const auto mousePos = qskMousePosition( event );
     const auto rect = subControlRect( ColdAndWarmArc );
 
+    bool arcContainsMousePos = arcContainsPoint( rect, mousePos );
+
+    if( !arcContainsMousePos )
+    {
+        setSkinStateFlag( Pressed, false );
+        return;
+    }
+
     const qreal ratioX = ( mousePos.x() - rect.x() ) / rect.width();
 
     setValueAsRatio( ratioX );
@@ -103,4 +112,38 @@ void LightDisplay::mouseReleaseEvent( QMouseEvent* /*event*/ )
     setSkinStateFlag( Pressed, false );
 }
 
+bool LightDisplay::arcContainsPoint( const QRectF& rect, const QPointF& point ) const
+{
+    // putting this in an own function just because it might be useful
+    // at other places in the future
+
+    const QskArcMetrics metrics = arcMetricsHint( ColdAndWarmArc );
+    const int tolerance = 10;
+
+    // 1. check angle
+    QPointF circlePos( point.x() - rect.center().x(),
+                 rect.center().y() - point.y() );
+
+    const qreal atan = qAtan2( circlePos.y(), circlePos.x() );
+    const qreal angle = qRadiansToDegrees( atan );
+    // the qAbs() actually only works for the 180 degrees case,
+    // we might want to generalize this later:
+    const bool angleWithinRange = ( qAbs( angle ) + tolerance ) > metrics.startAngle()
+            && qAbs( angle ) < ( metrics.startAngle() + metrics.spanAngle() - tolerance );
+
+    // 2. check whether point is on arc
+    const qreal radiusMax = rect.width() / 2;
+    const qreal arcWidth = metrics.width();
+    const qreal radiusMin = radiusMax - arcWidth;
+
+    const qreal polarRadius = qSqrt( qPow( circlePos.x(), 2 ) + qPow( circlePos.y(), 2 ) );
+    const bool pointOnArc = ( polarRadius + tolerance ) > radiusMin
+            && ( polarRadius - tolerance ) < radiusMax;
+
+    qDebug() << angleWithinRange << angle << pointOnArc;
+    bool ret = angleWithinRange && pointOnArc;
+
+    return ret;
+}
+
 #include "moc_LightDisplay.cpp"

examples/iotdashboard/LightDisplay.h

@@ -37,6 +37,8 @@ class LightDisplay : public QskBoundedValueInput
     void mouseReleaseEvent( QMouseEvent* e ) override;
 
   private:
+    bool arcContainsPoint( const QRectF&, const QPointF& ) const;
+
     QskShadowMetrics m_shadow;
     QColor m_shadowColor = Qt::black;
 

examples/iotdashboard/Skin.cpp

@@ -184,7 +184,7 @@ void Skin::initHints( const Palette& palette )
     // light intensity:
     ed.setBoxShape( LightDisplay::Panel, 100, Qt::RelativeSize );
 
-    ed.setArcMetrics( LightDisplay::ColdAndWarmArc, 8.785, 0, 0 );
+    ed.setArcMetrics( LightDisplay::ColdAndWarmArc, 8.785, 0, 180 * 16 );
     QskGradient coldGradient( Qt::Horizontal, { { 0.0, 0xffff3122 },
                                                 { 0.2, 0xfffeeeb7 },
                                                 { 0.3, 0xffa7b0ff },
@@ -195,7 +195,7 @@ void Skin::initHints( const Palette& palette )
     ed.setFontRole( LightDisplay::ValueText, QskSkin::LargeFont );
     ed.setColor( LightDisplay::ValueText, "#929cb2" );
 
-    ed.setStrutSize( LightDisplay::Knob, { 15.65, 15.65 } );
+    ed.setStrutSize( LightDisplay::Knob, { 20, 20 } );
     ed.setBoxBorderMetrics( LightDisplay::Knob, 1 );
     ed.setBoxBorderColors( LightDisplay::Knob, 0xffc4c4c4 );
     ed.setBoxShape( LightDisplay::Knob, 100, Qt::RelativeSize );