From e2304a3c7661228c3b016fa9a47b0f772bb2aeeb Mon Sep 17 00:00:00 2001
From: 23rd <23rd@vivaldi.net>
Date: Mon, 30 May 2022 14:03:39 +0300
Subject: [PATCH] Added ability to set pinned items for vertical layout
 reorder.

---
 ui/wrap/vertical_layout_reorder.cpp | 27 +++++++++++++++++++++++++++
 ui/wrap/vertical_layout_reorder.h   | 14 +++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/ui/wrap/vertical_layout_reorder.cpp b/ui/wrap/vertical_layout_reorder.cpp
index a750dfa..a4cc15f 100644
--- a/ui/wrap/vertical_layout_reorder.cpp
+++ b/ui/wrap/vertical_layout_reorder.cpp
@@ -75,6 +75,24 @@ void VerticalLayoutReorder::start() {
 	}
 }
 
+void VerticalLayoutReorder::addPinnedInterval(int from, int length) {
+	_pinnedIntervals.push_back({ from, length });
+}
+
+void VerticalLayoutReorder::clearPinnedIntervals() {
+	_pinnedIntervals.clear();
+}
+
+bool VerticalLayoutReorder::Interval::isIn(int index) const {
+	return (index >= from) && (index < (from + length));
+}
+
+bool VerticalLayoutReorder::isIndexPinned(int index) const {
+	return ranges::any_of(_pinnedIntervals, [&](const Interval &i) {
+		return i.isIn(index);
+	});
+}
+
 void VerticalLayoutReorder::mouseMove(
 		not_null<RpWidget*> widget,
 		QPoint position) {
@@ -105,6 +123,9 @@ void VerticalLayoutReorder::checkForStart(QPoint position) {
 }
 
 void VerticalLayoutReorder::updateOrder(int index, QPoint position) {
+	if (isIndexPinned(index)) {
+		return;
+	}
 	const auto shift = position.y() - _currentStart;
 	auto &current = _entries[index];
 	current.shiftAnimation.stop();
@@ -120,6 +141,9 @@ void VerticalLayoutReorder::updateOrder(int index, QPoint position) {
 	if (shift > 0) {
 		auto top = current.widget->y() - shift;
 		for (auto next = index + 1; next != count; ++next) {
+			if (isIndexPinned(next)) {
+				return;
+			}
 			const auto &entry = _entries[next];
 			top += entry.widget->height();
 			if (currentMiddle < top) {
@@ -137,6 +161,9 @@ void VerticalLayoutReorder::updateOrder(int index, QPoint position) {
 			moveToShift(next, 0);
 		}
 		for (auto prev = index - 1; prev >= 0; --prev) {
+			if (isIndexPinned(prev)) {
+				return;
+			}
 			const auto &entry = _entries[prev];
 			if (currentMiddle >= entry.widget->y() - entry.shift + currentHeight) {
 				moveToShift(prev, 0);
diff --git a/ui/wrap/vertical_layout_reorder.h b/ui/wrap/vertical_layout_reorder.h
index 1b28e76..87875b6 100644
--- a/ui/wrap/vertical_layout_reorder.h
+++ b/ui/wrap/vertical_layout_reorder.h
@@ -36,6 +36,8 @@ public:
 	void start();
 	void cancel();
 	void finishReordering();
+	void addPinnedInterval(int from, int length);
+	void clearPinnedIntervals();
 	[[nodiscard]] rpl::producer<Single> updates() const;
 
 private:
@@ -46,6 +48,12 @@ private:
 		int finalShift = 0;
 		int deltaShift = 0;
 	};
+	struct Interval {
+		[[nodiscard]] bool isIn(int index) const;
+
+		int from = 0;
+		int length = 0;
+	};
 
 	void mouseMove(not_null<RpWidget*> widget, QPoint position);
 	void mousePress(
@@ -66,13 +74,17 @@ private:
 
 	void updateScrollCallback();
 	void checkForScrollAnimation();
-	int deltaFromEdge();
+	[[nodiscard]] int deltaFromEdge();
+
+	[[nodiscard]] bool isIndexPinned(int index) const;
 
 	const not_null<Ui::VerticalLayout*> _layout;
 	Ui::ScrollArea *_scroll = nullptr;
 
 	Ui::Animations::Basic _scrollAnimation;
 
+	std::vector<Interval> _pinnedIntervals;
+
 	RpWidget *_currentWidget = nullptr;
 	int _currentStart = 0;
 	int _currentDesiredIndex = 0;