kotatogram/lib_ui
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Fix scrolling by scrollbar drag.

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This commit is contained in:
John Preston 2023-07-10 11:06:56 +04:00
parent 7135f3ed87
commit 081d1725af
2 changed files with 20 additions and 5 deletions
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24
ui/widgets/elastic_scroll.cpp
View file

@ -53,21 +53,24 @@ void ElasticScrollBar::refreshGeometry() {
return;
}
const auto available = extSize - fullSkip;
const auto scale = [&](int value) {
return (available * value) / _state.fullSize;
};
_area = _vertical
? QRect(skip, _st.deltat, thickness, available)
: QRect(_st.deltat, skip, available, thickness);
const auto barMin = std::min(st::scrollBarMin, available / 2);
const auto barWanted = scale(_state.visibleTill - _state.visibleFrom);
const auto visibleHeight = _state.visibleTill - _state.visibleFrom;
const auto scrollableHeight = _state.fullSize - visibleHeight;
const auto barWanted = (available * visibleHeight) / _state.fullSize;
if (barWanted >= available) {
_bar = _area = QRect();
hide();
return;
}
const auto bar = std::max(barMin, barWanted);
const auto outsideBar = available - bar;
const auto scale = [&](int value) {
return (outsideBar * value) / scrollableHeight;
};
const auto barFrom = scale(_state.visibleFrom);
const auto barTill = barFrom + bar;
const auto cutFrom = std::clamp(barFrom, 0, available - thickness);
@ -224,6 +227,16 @@ void ElasticScrollBar::leaveEventHook(QEvent *e) {
}
}
int ElasticScrollBar::scaleToBar(int change) const {
const auto scrollable = _state.fullSize
- (_state.visibleTill - _state.visibleFrom);
const auto outsideBar = (_vertical ? _area.height() : _area.width())
- (_vertical ? _bar.height() : _bar.width());
return (outsideBar <= 0 || scrollable <= outsideBar)
? change
: (change * scrollable / outsideBar);
}
void ElasticScrollBar::mouseMoveEvent(QMouseEvent *e) {
toggleOverBar(_bar.contains(e->pos()));
if (_dragging && !_bar.isEmpty()) {
@ -231,6 +244,7 @@ void ElasticScrollBar::mouseMoveEvent(QMouseEvent *e) {
const auto delta = position - _dragPosition;
_dragPosition = position;
if (auto change = _vertical ? delta.y() : delta.x()) {
change = scaleToBar(change);
if (_dragOverscrollAccumulated * change < 0) {
const auto overscroll = (change < 0)
? std::max(_dragOverscrollAccumulated + change, 0)

1
ui/widgets/elastic_scroll.h
View file

@ -56,6 +56,7 @@ private:
void leaveEventHook(QEvent *e) override;
void resizeEvent(QResizeEvent *e) override;
[[nodiscard]] int scaleToBar(int change) const;
[[nodiscard]] bool barHighlighted() const;
void toggleOver(bool over, anim::type animated = anim::type::normal);
void toggleOverBar(bool over, anim::type animated = anim::type::normal);