View: Adjust top margin when needed

[pulseview.git] / pv / view / view.cpp

diff --git a/pv/view/view.cpp b/pv/view/view.cpp
index c7944179ad5a7185de2dc3c0bf2a30c69ef09860..2fc14d2b64c9e777827650f7565125d1fe351aae 100644 (file)
--- a/pv/view/view.cpp
+++ b/pv/view/view.cpp
@@ -746,6 +746,30 @@ void View::calculate_tick_spacing()
        set_tick_precision(tick_precision);
 }
 
+void View::adjust_top_margin()
+{
+       assert(viewport_);
+
+       const QSize areaSize = viewport_->size();
+
+       const pair<int, int> extents = v_extents();
+       const int top_margin = owner_visual_v_offset() + extents.first;
+       const int trace_bottom = owner_visual_v_offset() + extents.first + extents.second;
+
+       // Do we have empty space at the top while the last trace goes out of screen?
+       if ((top_margin > 0) && (trace_bottom > areaSize.height())) {
+               const int trace_height = extents.second - extents.first;
+
+               // Center everything vertically if there is enough space
+               if (areaSize.height() >= trace_height)
+                       set_v_offset(extents.first -
+                               ((areaSize.height() - trace_height) / 2));
+               else
+                       // Remove the top margin to make as many traces fit on screen as possible
+                       set_v_offset(extents.first);
+       }
+}
+
 void View::update_scroll()
 {
        assert(viewport_);
@@ -955,8 +979,12 @@ bool View::eventFilter(QObject *object, QEvent *event)
        return QObject::eventFilter(object, event);
 }
 
-void View::resizeEvent(QResizeEvent*)
+void View::resizeEvent(QResizeEvent* event)
 {
+       // Only adjust the top margin if we shrunk vertically
+       if (event->size().height() < event->oldSize().height())
+               adjust_top_margin();
+
        update_layout();
 }