InpaintCanvas is a Tab stop with the focus ring only when on_brush
serves its keys, and takes the pen, the crosshair and the ring only
with on_stroke. new() asserts each stroke's radius within REACH and
its points on the picture. The settled strokes' cells stay cached, so
a drag paints only the stroke under the pen over a copy. The canvas
keeps square corners, so the wash fits the picture. The gallery drags
with moves.
ZacharyZhang-NY
d5129675c9