plugins/shakecursor: reset detector on mouse press

A sequence of mouse moves shouldn't trigger the effect if the user
presses any mouse button during the mouse moves.

src/plugins/shakecursor/shakecursor.cpp

@@ -94,11 +94,12 @@ void ShakeCursorEffect::animateTo(qreal magnification)
 
 void ShakeCursorEffect::pointerEvent(MouseEvent *event)
 {
-    if (event->type() != QEvent::MouseMove || event->buttons() != Qt::NoButton) {
+    if (event->buttons() != Qt::NoButton) {
+        m_shakeDetector.reset();
         return;
     }
 
-    if (input()->pointer()->isConstrained()) {
+    if (input()->pointer()->isConstrained() || event->type() != QEvent::MouseMove) {
         return;
     }
 

src/plugins/shakecursor/shakedetector.cpp

@@ -39,6 +39,11 @@ static inline bool sameSign(qreal a, qreal b)
     return (a >= -tolerance && b >= -tolerance) || (a <= tolerance && b <= tolerance);
 }
 
+void ShakeDetector::reset()
+{
+    m_history.clear();
+}
+
 bool ShakeDetector::update(QMouseEvent *event)
 {
     // Prune the old entries in the history.

src/plugins/shakecursor/shakedetector.h

@@ -22,6 +22,7 @@ class ShakeDetector
 public:
     ShakeDetector();
 
+    void reset();
     bool update(QMouseEvent *event);
 
     quint64 interval() const;