From 7b6042168a345c867961aa9eac13dd21325d9159 Mon Sep 17 00:00:00 2001
From: Mike Solar <iam@mikesolar.cn>
Date: Wed, 5 Aug 2026 14:53:04 +0800
Subject: [PATCH] fix(widget): harden TimelineAndTrackView teardown and
 TimeScaledObject limits

- TimelineAndTrackView: disconnect the scrollbar sync connections in the
  destructor. Child views reset their scene during destruction, which can
  re-emit QScrollBar::valueChanged into a half-destroyed object and trip
  Qt's assertObjectType abort.
- TimeScaledObject: keep minimum <= maximum when setting scale limits so
  set_scale()'s std::clamp is never called with inverted limits (UB).
  Setting the maximum below the minimum now pulls the minimum down, and
  vice versa, matching QAbstractSlider conventions.
---
 app/widget/timebased/timescaledobject.cpp          | 12 ++++++++++++
 app/widget/timelinewidget/timelineandtrackview.cpp | 10 ++++++++++
 app/widget/timelinewidget/timelineandtrackview.h   |  2 ++
 3 files changed, 24 insertions(+)

diff --git a/app/widget/timebased/timescaledobject.cpp b/app/widget/timebased/timescaledobject.cpp
index 7e436d368..b72f84349 100644
--- a/app/widget/timebased/timescaledobject.cpp
+++ b/app/widget/timebased/timescaledobject.cpp
@@ -116,6 +116,12 @@ void TimeScaledObject::set_maximum_scale(const double &max)
 {
 	max_scale_ = max;
 
+	// Keep min <= max so the clamp in set_scale() is never called with
+	// inverted limits (undefined behavior)
+	if (min_scale_ > max_scale_) {
+		min_scale_ = max_scale_;
+	}
+
 	if (get_scale() > max_scale_) {
 		set_scale(max_scale_);
 	}
@@ -125,6 +131,12 @@ void TimeScaledObject::set_minimum_scale(const double &min)
 {
 	min_scale_ = min;
 
+	// Keep min <= max so the clamp in set_scale() is never called with
+	// inverted limits (undefined behavior)
+	if (max_scale_ < min_scale_) {
+		max_scale_ = min_scale_;
+	}
+
 	if (get_scale() < min_scale_) {
 		set_scale(min_scale_);
 	}
diff --git a/app/widget/timelinewidget/timelineandtrackview.cpp b/app/widget/timelinewidget/timelineandtrackview.cpp
index fede8e1f0..76bd1c234 100644
--- a/app/widget/timelinewidget/timelineandtrackview.cpp
+++ b/app/widget/timelinewidget/timelineandtrackview.cpp
@@ -54,6 +54,16 @@ TimelineAndTrackView::TimelineAndTrackView(Qt::Alignment vertical_alignment,
 	splitter_->setSizes({ 180, width() });
 }
 
+TimelineAndTrackView::~TimelineAndTrackView()
+{
+	// When the child views are destroyed they reset their scene, which can
+	// push a valueChanged through these connections while this object is
+	// already half-destroyed (Qt aborts on a slot invoked past its class's
+	// destructor). Detach first so teardown emissions go nowhere.
+	disconnect(view_->verticalScrollBar(), nullptr, this, nullptr);
+	disconnect(track_view_->verticalScrollBar(), nullptr, this, nullptr);
+}
+
 QSplitter *TimelineAndTrackView::splitter() const
 {
 	return splitter_;
diff --git a/app/widget/timelinewidget/timelineandtrackview.h b/app/widget/timelinewidget/timelineandtrackview.h
index 7181aebcd..b0cafb633 100644
--- a/app/widget/timelinewidget/timelineandtrackview.h
+++ b/app/widget/timelinewidget/timelineandtrackview.h
@@ -42,6 +42,8 @@ public:
 
 	TrackView *track_view() const;
 
+	virtual ~TimelineAndTrackView() override;
+
 private:
 	QSplitter *splitter_;