spline-widget: simplify/fix drawing logic

The linear things should be drawn in drawFunction() since they
change only when some control point is moved and the spline is
recalculated anyway.

Introduce spline::get_value_no_save to avoid clobbering the
tracked value.

Draw linear helper before the spline to avoid occluding it.

Remove some redundant checks for whether _config exists when all
calling sites ensure it already.

I still need to de-camel-case these two classes.

1 files changed, 1 insertions, 0 deletions

diff --git a/spline-widget/spline.hpp b/spline-widget/spline.hpp
index fa13a171..b7a8e343 100644
--- a/spline-widget/spline.hpp
+++ b/spline-widget/spline.hpp
@@ -81,6 +81,7 @@ public:
     spline(const spline&) = default;
 
     float getValue(double x);
+    float get_value_no_save(double x);
     bool getLastPoint(QPointF& point);
     void removePoint(int i);
     void removeAllPoints();