NSCollectionView + custom layout => missing vertical drop line
NSCollectionView + custom layout => missing vertical drop line
- Subject: NSCollectionView + custom layout => missing vertical drop line
- From: Stephane Sudre via Cocoa-dev <email@hidden>
- Date: Tue, 14 Jul 2020 17:32:32 +0200
I'm currently playing with NSCollectionView (10.11+ behavior) and have
not been able to figure out a mystery when it comes to drag and drop.
I have a NSCollectionView with a custom layout.
The layout is based on the standard grid layout with the following
modifications in mind:
- there can only be one row.
- there are as many columns as items.
- the collection view can be scrolled horizontally.
- the width of the items is fixed.
- the height of the items is the height of the contents.
The mystery I'm facing is that during a local drag and drop (to switch
items), the vertical line indicating the target of the drop does not
appear.
The mysterious side here is that if I change the maximumNumberOfRows
to 0, it does appear but I lose the horizontal scrolling.
Since this is the first time I try to use the NSCollectionView class
with a custom layout, I'm probably doing something wrong. But I have
not found so far an obvious solution from the miscellaneous tutorials
here and there.
So if anyone has an idea what's wrong, I'm interested.
Sample project:
Warning: the drop indexes are computed incorrectly for the moment.
Dragging and dropping the first card between the second and third ones
is safe.
https://drive.google.com/file/d/1LsDrWjK7vg3ET8yGLaLR1OpojfA4Tlrr/view?usp=sharing
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