painter abstract method
A painter filling the whole calculator surface. Inside
textSafeArea (the display text) it keeps the display legible: a
solid surface behind the text, no pattern. Scene art in the toolbar
row keeps clear of toolbarExclusion (the mode button). With
reduceMotion any drift is frozen.
Implementation
CustomPainter painter({
Rect? textSafeArea,
Rect? toolbarExclusion,
bool reduceMotion = false,
});