Dynamic control width in a scrollable area

Targets iOS
1

In a custom table cell I have a scrollable area.
I need to put X container controls within it, and I need to resize each to the width of the scrollable area.
I’ve tried setting a constraint dynamical but it crashes hard without raising an exception.

I’m missing something. I assumed that if I set each container’s width constraint to the width attribute of the scrollable area, this should work fine. Is the scrollable area not a “legal” parent of a container control that has been added to it?

2

It is usually a bad idea to have a vertical scrollable area within a table.
A table is already a subclass of scrollable area.

Anyway, it should still be possible.

Correct. The legal parent of any control in a MobileScrollabelArea is the MobileScrollableArea.Container which you must instantiate yourself.

  1. Make sure your scrollable area has a Container that is not nil.
MobileScrollableArea.Container = new MobileContainer //This should suffice

  1. Set the Container’s width to be equal to the scrollableArea’s width.

  2. You will then add X container controls as Childs of that container.

  3. Set each container’s width to be equal to MobileScrollableArea.Container’s width

3

I’ve been trying. It doesn’t want to work.
The .container reports back width and height of 0
When I dynamically add a control to it, it just never shows up.

4

ahhhh. I was setting the constraint on the control, not the container.
Starting to make progress now.

1 Like
5

Can you make a test project with just that part?

I will then be able to take a look at it

6

No need now. The trick was to add the constraint to the correct object and then to add a constraint for the width of the scroll areas container.

7

I meant to follow up with this.
It’s still not quite right.

I get the width of the scrollable area and set a new container to add the elements that will show up when scrolled. I’m setting Paging to true.

I then set the container’s width to the scrollable area’s width x the number of controls I’m embedding.
I loop through each control and set its with to the width of the scrollable area, and left edge to the correct constraint - either the container’s left edge or the right edge of the container that proceeded it.

There is some disconnect because as I swipe the next controls appear cut off or at least not correctly paging (see one sticking out).

Here’s the code. Any hints about what I might be doing wrong would be appreciated.

(Could it be not compensating for the scrollbar width or something?)

For i As Integer = 0 To cont.ControlCount-1
Var cv As MobileControl=cont.ControlAt(i)

Var WidthC As New iOSLayoutConstraint(cv,iOSLayoutConstraint.AttributeTypes.Width, iOSLayoutConstraint.RelationTypes.Equal, _
cont, iOSLayoutConstraint.AttributeTypes.Width,1/cont.ControlCount,0)

Var HeightC As New iOSLayoutConstraint(cv,iOSLayoutConstraint.AttributeTypes.Height, iOSLayoutConstraint.RelationTypes.Equal, _
Nil, iOSLayoutConstraint.AttributeTypes.None,1.0,h)

Var LeftC As iOSLayoutConstraint

If i=0 Then
leftc= New iOSLayoutConstraint(cv,iOSLayoutConstraint.AttributeTypes.Left, iOSLayoutConstraint.RelationTypes.Equal, _
cont, iOSLayoutConstraint.AttributeTypes.Left,1.0, 0 )
Else
leftc = New iOSLayoutConstraint(cv,iOSLayoutConstraint.AttributeTypes.Left, iOSLayoutConstraint.RelationTypes.Equal, _
cont.ControlAt(i-1), iOSLayoutConstraint.AttributeTypes.Right,1.0, 0 )
End If

cont.AddConstraint heightC
cont.AddConstraint widthC
cont.addconstraint leftC

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