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plugins/shakedetector: Optimize ShakeDetector

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Only store one history item for movement in the same direction.
With this optimization I measure m_history.size() <= 15 for all kinds of
movements, including back and forth, and circular.
This commit is contained in:
Vlad Zahorodnii 2024-01-17 22:42:37 +02:00 committed by Yifan Zhu
parent 0bc60023f5
commit dcd20922d9
1 changed files with 19 additions and 0 deletions
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19
src/plugins/shakecursor/shakedetector.cpp
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@ -32,6 +32,13 @@ void ShakeDetector::setSensitivity(qreal sensitivity)
m_sensitivity = sensitivity;
}
static inline bool sameSign(qreal a, qreal b)
{
constexpr qreal tolerance = 1;
// movements less than tolerance count as movements in any direction
return (a >= -tolerance && b >= -tolerance) || (a <= tolerance && b <= tolerance);
}
bool ShakeDetector::update(QMouseEvent *event)
{
// Prune the old entries in the history.
@ -45,6 +52,18 @@ bool ShakeDetector::update(QMouseEvent *event)
m_history.erase(m_history.begin(), it);
}
if (m_history.size() >= 2) {
HistoryItem &last = m_history[m_history.size() - 1];
const HistoryItem &prev = m_history[m_history.size() - 2];
if (sameSign(last.position.x() - prev.position.x(), event->localPos().x() - last.position.x()) && sameSign(last.position.y() - prev.position.y(), event->localPos().y() - last.position.y())) {
last = HistoryItem{
.position = event->localPos(),
.timestamp = event->timestamp(),
};
return false;
}
}
m_history.emplace_back(HistoryItem{
.position = event->localPos(),
.timestamp = event->timestamp(),