64 lines
1.3 KiB
C++
64 lines
1.3 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/dragging_scroll_manager.h"
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#include "base/timer.h"
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namespace Ui {
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namespace {
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// 37px per 15ms while select-by-drag.
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inline constexpr auto kMaxScrollSpeed = 37;
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} // namespace
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DraggingScrollManager::DraggingScrollManager() = default;
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void DraggingScrollManager::scrollByTimer() {
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const auto d = (_delta > 0)
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? std::min(_delta * 3 / 20 + 1, kMaxScrollSpeed)
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: std::max(_delta * 3 / 20 - 1, -kMaxScrollSpeed);
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_scrolls.fire_copy(d);
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}
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void DraggingScrollManager::checkDeltaScroll(int delta) {
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_delta = delta;
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if (_delta) {
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if (!_timer) {
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_timer = std::make_unique<base::Timer>([=] { scrollByTimer(); });
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}
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_timer->callEach(15);
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} else {
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cancel();
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}
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}
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void DraggingScrollManager::checkDeltaScroll(
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const QPoint &point,
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int top,
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int bottom) {
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const auto diff = point.y() - top;
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checkDeltaScroll((diff < 0)
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? diff
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: (point.y() >= bottom)
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? (point.y() - bottom + 1)
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: 0);
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}
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void DraggingScrollManager::cancel() {
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if (_timer) {
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_timer->cancel();
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_timer = nullptr;
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}
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}
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rpl::producer<int> DraggingScrollManager::scrolls() const {
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return _scrolls.events();
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}
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} // namespace Ui
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