74 lines
1.6 KiB
C++
74 lines
1.6 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop application for the Telegram messaging service.
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For license and copyright information please follow this link:
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https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
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*/
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#include "ui/chat/continuous_scroll.h"
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#include <QScrollBar>
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#include <QWheelEvent>
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namespace Ui {
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void ContinuousScroll::wheelEvent(QWheelEvent *e) {
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if (_tracking
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&& !e->angleDelta().isNull()
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&& (e->angleDelta().y() < 0)
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&& (scrollTopMax() == scrollTop())) {
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_addContentRequests.fire({});
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if (base::take(_contentAdded)) {
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viewportEvent(e);
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}
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return;
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}
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ScrollArea::wheelEvent(e);
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}
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void ContinuousScroll::setTrackingContent(bool value) {
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if (_tracking == value) {
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return;
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}
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_tracking = value;
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reconnect();
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}
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void ContinuousScroll::reconnect() {
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if (!_tracking) {
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_connection.release();
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return;
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}
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const auto handleAction = [=](int action) {
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const auto scroll = verticalScrollBar();
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const auto step = (action == QAbstractSlider::SliderSingleStepAdd)
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? scroll->singleStep()
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: (action == QAbstractSlider::SliderPageStepAdd)
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? scroll->pageStep()
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: 0;
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if (!action) {
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return;
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}
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const auto newTop = scrollTop() + step;
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if (newTop > scrollTopMax()) {
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_addContentRequests.fire({});
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if (base::take(_contentAdded)) {
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scroll->setSliderPosition(newTop);
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}
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}
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};
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_connection = QObject::connect(
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verticalScrollBar(),
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&QAbstractSlider::actionTriggered,
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handleAction);
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}
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void ContinuousScroll::contentAdded() {
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_contentAdded = true;
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}
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rpl::producer<> ContinuousScroll::addContentRequests() const {
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return _addContentRequests.events();
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}
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} // namespace Ui
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