Add verticalSortableList collision detection strategy

[ceddlyburge]

Fixes #804

Probably this will want a little demo or something added, if you are happy with it, maybe in Stories?

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[marcospassos]

I spent a few hours trying to understand the weird behavior we were expecting here until I finally found this issue. I can confirm that this collision strategy makes vertical lists that don't use drag overlay work properly.

It would be really helpful to have this as a building collision strategy to avoid this boilerplate code everywhere.

[ceddlyburge]

One thing to note is that it doesn't work with autoscrolling (scrolling the container while dragging). We have been using this code with the autoscrolling option turned off for a while now, and it's been working fine, so I think it's solid.

[TheMikeyRoss]

any update on this one? could it possibly be related to an issue that looks like this

[ceddlyburge]

You could copy the code in to your project and see if it fixes the problem?

[TheMikeyRoss]

Thanks @ceddlyburge for your reply,

May I ask how do I use verticalSortableListCollisionDetection in my code?

[ceddlyburge]

Its surprisingly easy!

Just copy all the code in this PR somewhere, and then pass the function in to the DndContext.

<DndContext
      collisionDetection={verticalSortableListCollisionDetection}
      autoScroll={false}
      ...
>

[TheMikeyRoss]

Awesome, thanks @ceddlyburge 👍

[TheMikeyRoss]

@ceddlyburge It works wonderfully! I really appreciate it ♥
Here's a demo below 👇

Before

After

[ceddlyburge]

No worries, glad you like it :)
Also, nice demo :)

[ozdemircibaris]

@ceddlyburge
Hello Cedd,
I have a similar problem too. Actually, the only difference is that my structure is horizontal. I refactored your code according to horizontal style, but it did not work as I wanted. Can you help me too?

dnd.bug.mov

import { CollisionDetection, DroppableContainer } from '@dnd-kit/core';
import { sortBy } from 'lodash';

export const horizontalSortableListCollisionDetection: CollisionDetection = (
  args
) => {
  if (args.collisionRect.left < (args.active.rect.current?.initial?.left ?? 0)) {
    return leftmostDroppableContainerMajorityCovered(args);
  } else {
    return rightmostDroppableContainerMajorityCovered(args);
  }
};

const leftmostDroppableContainerMajorityCovered: CollisionDetection = ({
  droppableContainers,
  collisionRect,
}) => {
  const ascendingDroppableContainers = sortBy(
    droppableContainers,
    (c) => c?.rect.current?.left
  );

  for (const droppableContainer of ascendingDroppableContainers) {
    const {
      rect: { current: droppableRect },
    } = droppableContainer;

    if (droppableRect) {
      const coveredPercentage =
        (droppableRect.left + droppableRect.width - collisionRect.left) /
        droppableRect.width;

      if (coveredPercentage > 0.5) {
        return [collision(droppableContainer)];
      }
    }
  }

  return [collision(ascendingDroppableContainers[0])];
};

const rightmostDroppableContainerMajorityCovered: CollisionDetection = ({
  droppableContainers,
  collisionRect,
}) => {
  const descendingDroppableContainers = sortBy(
    droppableContainers,
    (c) => c?.rect.current?.left
  ).reverse();

  for (const droppableContainer of descendingDroppableContainers) {
    const {
      rect: { current: droppableRect },
    } = droppableContainer;

    if (droppableRect) {
      const coveredPercentage =
        (collisionRect.right - droppableRect.left) / droppableRect.width;

      if (coveredPercentage > 0.5) {
        return [collision(droppableContainer)];
      }
    }
  }

  return [collision(descendingDroppableContainers[0])];
};

const collision = (droppableContainer?: DroppableContainer) => {
  return {
    id: droppableContainer?.id ?? '',
    value: droppableContainer,
  };
};

[ceddlyburge]

Hi Baris, I'll take a look when I get some time. I can't remember all the details of this, but hopefully it will come back to me fairly quickly :)

[ozdemircibaris]

I am waiting for your return, thank you very much

[ceddlyburge]

HI Baris, this looks like it should work to me, do you have some example code I can debug?
Thanks, Cedd

[ozdemircibaris]

Hi Cedd, I will prepare it quickly and share the link
Thanks

[ozdemircibaris]

Hey Cedd,
Sorry for the late reply, I don't have any problems right now, my above code works.

[ceddlyburge]

Ah great, glad to hear it!
Maybe you could add the horizontalSortableListCollisionDetection to this PR?

[ozdemircibaris]

Yes of course!

[ceddlyburge]

I've added horizontalSortableListCollisionDetection to this PR now, hopefully it will be useful for someone in the future.

[TheMikeyRoss]

Amazon work @ceddlyburge 👍

@clauderic could this be merged? or is it gonna have some potential conflict with your planned refactoring mentioned [here] ?(#1194 (comment))