Viewport: scroll horizontally with the vertical wheel and the shift key

Some software (notably Gimp and Inkscape) allows horizontal scrolling
with the vertical wheel when the shift key is pressed. Implement this
behaviour for easier navigation with single wheel mice.

diff --git a/pv/views/trace/viewport.cpp b/pv/views/trace/viewport.cpp
index bab4f95368aa55569ef95bffb2c91a712b72d3e5..7ab24eadd3ffd9bd4f8edd30679d8cde0de74f08 100644 (file)
--- a/pv/views/trace/viewport.cpp
+++ b/pv/views/trace/viewport.cpp
@@ -241,6 +241,12 @@ void Viewport::wheelEvent(QWheelEvent *event)
                        // is intrepretted as vertical scrolling
                        view_.set_v_offset(-view_.owner_visual_v_offset() -
                                (delta * height()) / (8 * 120));
+               } else if (event->modifiers() & Qt::ShiftModifier) {
+                       // Vertical scrolling with the shift key pressed
+                       // acts as horizontal scrolling like in Gimp
+                       // and Inkscape.
+                       view_.set_scale_offset(view_.scale(),
+                               - delta * view_.scale() + view_.offset());
                } else {
                        // Vertical scrolling is interpreted as zooming in/out
 #if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)