From: Soeren Apel <redacted>
Date: Tue, 11 Feb 2020 18:06:11 +0000 (+0100)
Subject: TraceView: Implement view scroll margins
X-Git-Url: https://sigrok.org/gitaction?a=commitdiff_plain;h=6381b375ae391a79ab50f1f5dcbe0014ff9bd46c;p=pulseview.git

TraceView: Implement view scroll margins
---

diff --git a/pv/views/trace/view.cpp b/pv/views/trace/view.cpp
index 6159cdd9..e5cf980a 100644
--- a/pv/views/trace/view.cpp
+++ b/pv/views/trace/view.cpp
@@ -94,8 +94,10 @@ const Timestamp View::MinScale("1e-12");
 
 const int View::MaxScrollValue = INT_MAX / 2;
 
-const int View::ScaleUnits[3] = {1, 2, 5};
+/* Area at the top and bottom of the view that can't be scrolled out of sight */
+const int View::ViewScrollMargin = 50;
 
+const int View::ScaleUnits[3] = {1, 2, 5};
 
 CustomScrollArea::CustomScrollArea(QWidget *parent) :
 	QAbstractScrollArea(parent)
@@ -1245,9 +1247,13 @@ void View::update_scroll()
 	const pair<int, int> extents = v_extents();
 
 	// Don't change the scrollbar range if there are no traces
-	if (extents.first != extents.second)
-		vscrollbar->setRange(extents.first - areaSize.height(),
-			extents.second);
+	if (extents.first != extents.second) {
+		int top_margin = ViewScrollMargin;
+		int btm_margin = ViewScrollMargin;
+
+		vscrollbar->setRange(extents.first - areaSize.height() + top_margin,
+			extents.second - btm_margin);
+	}
 
 	if (scroll_needs_defaults_) {
 		set_scroll_default();
diff --git a/pv/views/trace/view.hpp b/pv/views/trace/view.hpp
index c2cceb27..bf8b6432 100644
--- a/pv/views/trace/view.hpp
+++ b/pv/views/trace/view.hpp
@@ -96,6 +96,7 @@ private:
 	static const pv::util::Timestamp MinScale;
 
 	static const int MaxScrollValue;
+	static const int ViewScrollMargin;
 
 	static const int ScaleUnits[3];