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Fixed graph slider position computation

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This commit is contained in:
Martin Tůma 2016-03-22 19:19:59 +01:00
parent b1b8d68610
commit e0fd77bbfd
1 changed files with 38 additions and 3 deletions
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41
src/graphview.cpp
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@ -288,6 +288,37 @@ void GraphView::clear()
_scene->setSceneRect(0, 0, 0, 0); _scene->setSceneRect(0, 0, 0, 0);
} }
static qreal yAtX(const QPainterPath &path, qreal x)
{
int low = 0;
int high = path.elementCount() - 1;
int mid = 0;
while (low <= high) {
mid = low + ((high - low) / 2);
const QPainterPath::Element &e = path.elementAt(mid);
if (e.x > x)
high = mid - 1;
else if (e.x < x)
low = mid + 1;
else
return e.y;
}
QLineF l;
if (path.elementAt(mid).x < x) {
Q_ASSERT(mid >= 0 && mid+1 < path.elementCount());
l = QLineF(path.elementAt(mid).x, path.elementAt(mid).y,
path.elementAt(mid+1).x, path.elementAt(mid+1).y);
} else {
Q_ASSERT(mid-1 >= 0 && mid < path.elementCount());
l = QLineF(path.elementAt(mid-1).x, path.elementAt(mid-1).y,
path.elementAt(mid).x, path.elementAt(mid).y);
}
return l.pointAt((x - l.p1().x()) / (l.p2().x() - l.p1().x())).y();
}
void GraphView::emitSliderPositionChanged(const QPointF &pos) void GraphView::emitSliderPositionChanged(const QPointF &pos)
{ {
if (_graphs.isEmpty()) if (_graphs.isEmpty())
@ -296,15 +327,19 @@ void GraphView::emitSliderPositionChanged(const QPointF &pos)
qreal val = pos.x() / _slider->area().width(); qreal val = pos.x() / _slider->area().width();
emit sliderPositionChanged(val * (_xMax - _xMin)); emit sliderPositionChanged(val * (_xMax - _xMin));
if (!_sliderInfo->isVisible())
return;
const QPainterPath &path = _graphs.at(0)->path(); const QPainterPath &path = _graphs.at(0)->path();
QRectF br = path.boundingRect(); QRectF br = path.boundingRect();
if (br.height() < _minRange) if (br.height() < _minRange)
br.adjust(0, -(_minRange/2 - br.height()/2), 0, br.adjust(0, -(_minRange/2 - br.height()/2), 0,
_minRange/2 - br.height()/2); _minRange/2 - br.height()/2);
QPointF p = path.pointAtPercent(val);
qreal r = (p.y() - br.bottom()) / br.height(); qreal y = yAtX(path, val * (_xMax - _xMin));
qreal r = (y - br.bottom()) / br.height();
_sliderInfo->setPos(QPointF(0, _slider->boundingRect().height() * r)); _sliderInfo->setPos(QPointF(0, _slider->boundingRect().height() * r));
_sliderInfo->setText(QString::number(-p.y() * _yScale, 'f', _precision)); _sliderInfo->setText(QString::number(-y * _yScale, 'f', _precision));
} }
qreal GraphView::sliderPosition() const qreal GraphView::sliderPosition() const