[tbolis]

Summary

onChange was called 10 ms after every mouse up and mouse out on the canvas, whether or not the drawing changed (issue #80). A click which only selects, a drag of the pan tool, and a pointer which comes and goes all called it.

• The events manager notes that an object was added, modified or removed since the mouse was pressed, and tells the application only then.
• A change is told once: a drawing which the mouse leaves the canvas in the middle of calls onChange at the mouse out, and the release outside of the canvas has nothing more to tell.
• A change made before the press (an object added by code) does not make the next click one.
• undo, redo and the load of a value call onChange as before. The eraser, the laser pointer and the polygon tell the application themselves, as before. A pinch gesture still calls nothing.
• README: the onChange row, and the limitation of Add functions like onUpdate() or onChange() with old snapshots and newly added objects. #80 is removed. The limitation "Drawing an arrow records undo steps which have no visible effect" is removed too, as fix: an arrow is one undo step #201 fixed it. CHANGELOG: a line under Changed in 1.1.0. The type comment of onChange follows.

Changes of behavior

An application which used onChange as "the mouse was released" now gets it only when the sketch changed. The objects it needs are in onObjectAdded, onObjectModified and onObjectRemoved, which are not changed.

Checks

yarn format:check, yarn lint, yarn typecheck and yarn build pass. yarn test: 434 passing and 1 todo. The new tests, the onChange ones in SketchField.spec.tsx and onChange.spec.tsx (with the mouse events of the browser: a drawing, the move of an object with the select tool, a click which selects, a drag in the empty part, a pointer which leaves, a mouse out in the middle of a drawing, a free stroke, the pan tool), fail without the change: 7 of them.

Notes for review

• Add functions like onUpdate() or onChange() with old snapshots and newly added objects. #80 needs to be in the Fixes line of the release PR (Release v1.1.0 #196), as closing keywords do not act on a merge into release/1.1.0.
• Not checked: a physical touch device.