useDndMonitor onDragStart not called when there is an activationConstraint and collisionDetection is closestCorners

[mkelliher]

Repro

1. Create a DndContext with:
   • A pointer sensor with an activation constraint: useSensor(PointerSensor, { activationConstraint: { distance: 10 } })
   • collisionDetection={closestCorners}
   • A draggable and a droppable component
2. Somewhere in a child component within the context, put useDndMonitor({ onDragStart: () => console.log('useDndMonitor: onDragStart') })
3. Notice that the useDndMonitor: onDragStart is not logged when a drag is started.

I have set up the repro in a CodeSandbox here: https://codesandbox.io/s/dnd-kit-ondragstart-bug-zysht?file=/src/App.js

When you drag the item by its red drag handle, take a look at the console logs. You will see that the DndContext: onDragStart is called, but the useDndMonitor: onDragStart is not.

Workaround

I found that this issue does not occur if the collisionDetection function returns null at the start of the drag. So the workaround is to have collisionDetection always return null until DndContext: onDragStart is called. Then, after that, have the function return its regular results (i.e., closestCorners).

See the above CodeSandbox for an example of the workaround (in App.js use collisionDetection={collisionDetectionWorkaround}).

[clauderic]

This is fixed by this commit, which will be released in the next major version:
05d6a78#diff-c4e29cc1eb5f250d1c1ff78d14b5785fb2a003b7aa2c8821dfecf20bc9d86325R387-R391

You can follow the release PR here #342

If you're eager to jump to the next version before it's released, you can install versions tagged with @next on npm.

See this forked sandbox where the issue is no longer reproducible if you upgrade to the @next version of @dnd-kit/core https://codesandbox.io/s/dnd-kit-ondragstart-bug-forked-utdlw?file=/src/Draggable.js