ListView - change selection from script & SHIFT multiselect

Hello,

I am implementing a listview in which the user can create and delete elements. The list view uses the Multiselect selection type. I would also like to allow the user to Undo/Redo add/remove operations from the list. The problem is that when I delete the selected items (which I need to keep track of manually via the onSelectionChanged callback), the list doesn't change its selection information even though I am calling Refresh() so the selected indices are mapped to whatever remains in the list.

I tried setting the selected index to -1. It works, however, now if I Undo the operation, the selection disappears. I can bring the items back in the list, but I can not reselect the items.

So here are a few suggestions for the list view:
1. the possibility to retrieve ALL selected indices. If there is such thing as Multiselect selection type, it stands to reason that there should be a way to retrieve all selected indices. Not just the first index.
2. the possibility to change the selected indices manually. Useful for the handling of Undo/Redo situations such as the one described above. Might be useful in other scenarios too.
3. it would be nice to have SHIFT + ARROW multi select. For example, in the hierarchy view, if I hold down SHIFT and then press UP/DOWN, the selection grows or shrinks. The ListView class only supports SHIFT in conjunction with the mouse. UP/DOWN are not currently supported. Not super important, but it would definitely be nice to have.

4 (SUPER NICE TO HAVE ). a list view class with elements arranged in a grid-like manner. In my case I need this to render a list of prefab previews. The previews must be treated as list items which can be selected, deleted etc. For the moment, it seems I will have to implement this functionality myself. Not a biggie, but it would help a lot to have a list view with a grid layout.

Thanks,
Andrew

 

Hi uDamian,

Thanks for the response. Are there any plans to allow us to retrieve all selected items (regardless of the way in which the item id is mapped)? Also is there a way to serialize the selection between script reloads?

EDIT: I will definitely check the implementation in the link you gave me. That should be very helpful. I'm sure I can mess around with it and change it for my own needs

 

Awesome! It's a great API! I love using it, it's just that in its current state there seem to be a few setbacks .

Nevertheless, great job! I can't wait to see it improved!

 

@uDamian
I just have one more question Is there any plan to implement a list view that arranges elements in a grid-like manner. This is related to my ScrollView post (which by the way - problem solved!). So instead of having items arranged one below the other, have them sit one after the other on the same row and only move to the next row when there is no more room.

I am asking this because I might need to implement this list view class myself if this is not/will be available. I just don't want to start working on it if it's already there or if there are plans to implement it.

 

Thanks Damian,

What I am trying to accomplish is this:


I did that with IMGUI.

I have already started working on a custom ListView class. I still have trouble with the selection mechansim in the current ListView implementation. Plus there are a few things I would need like SHIFT + ARROW select and also be able to select with LEFT and RIGHT arrow keys.

I do have one question though. Do you think it would hurt performance too much if I didn't implement the recycle mechanism? Basically, I am planning to leave all elements there as they are created. For the moment at least, element recycling is not something I am willing to implement

 

Thanks uDamian,

That's what I did and it works great. I made a list view that supports 2 different types of layouts: Standard and Grid. No recycling. Works like a charm

Thanks!

 

Hi @uDamian ,

I just noticed that when a scroll view has the following properties set:
contentContainer.style.flexDirection = Row;
contentContainer.style.flexWrap = Wrap;

the vertical scrollbar disappears. For example:



This is an example of a list view I implemented to support grid layout. All previews are children of a scroll view that uses the above mentioned style. The scroll view uses the Vertcal ScrollViewMode.

If I set the flex direction to Column, the scroll bar appears. It seems that Row flex direction with wrapping does not support a vertical scrollbar. It would be great if this could be changed In this situation I need to scroll the contents of the window to show the prefabs below.

Thanks,
Andrew

 

Ok. But is there a way to add a vertical scrollbar to achieve the grid layout effect? If there isn't, this basicly renders the combination of FlexDirection.Row and FlexWrap.Wrap quite limited It is very common to have elements arranged in a grid layout that go outside the bounds of the view area.

 

Oh... Works like a charm! I really thought I was going to have to drop what I've done up until this point and use IMGUI instead . Thank you very much!

 

Thanks jonathanma_unity!
I solved it like this:

Code (CSharp):

1. var scrollView = new ScrollView();
2. rootVisualElement.Add(scrollView);
3. var gridContainer = new VisualElement();
4. gridContainer.style.flexDirection = FlexDirection.Row;
5. gridContainer.style.flexWrap = Wrap.Wrap;        
6. scrollView.Add(gridContainer);
7.          
8. for (int i = 0; i < 10; i++)
9. {
10.     var item = new VisualElement();
11.     item.style.width = 200;
12.     item.style.height= 200;
13.     item.style.backgroundColor = Color.black;            
14.     gridContainer.Add(item);
15. }