Problem summary: code-behind positioning is ignored if some tiles are collapsed unless a delay is introduced.

I have 12 tiles in 2 columns, all in restored state.

When all have their visibility set to visible I can set the position in the constructor of the hosting usercontrol and it works.

However if some of the tiles are collapsed, then the positioning is ignored (it seems) unless I introduce a delay of about 1/2 sec.

I tried putting the positioning code in the usercontrol loaded event, and even in the tileview loaded event, with no improvement.

 It seems that if tiles with a position prior the ones being positioned are collapsed the problem occurs.

 I noticed that if the position of the 12 tiles are defined in xaml as  0,1,2,3,4,5,6,7,8,9,10,11, that is, in order, then when tiles 2..6 are set to collapsed then the position order at run time is 0,1,2,2,2,2,2,2,3,4,5,6.  So the collapsed tiles all have a position of 2, and tile 7 has a position of 2, 8-3, and so on.

 When I set the position I only position visible tiles, and then with the position index starting with 0 and ending with visible_count-1, like in the 2nd set of position orders above.  I do not set the positions in order of position but rather in ​order of occurrence, that is for example I iterate through the tile list and set the position of item 0 to 3, item 1 to 0, item 2 to 2, and so on.

I have IsItemsAnimationEnabled = False and PreservePositiojnWhenMaximized=True

 I'm giving you all this info because I don't know what is relevant and what is not.  Again, if I introduce a timer delay the tiles position properly.

Additional Info:

After positioning and the display shows the incorrect position, an inspection of the position values shows the correct position.  So the tiles think they are in the correct position, so it looks like a screen update problem?  I tried doing a tileview.updatelayout and a layoutroot.updateloayout with no success.

 Also a delay as small as 100ms is enough to have the control render correctly, but of course this is not ideal.

Is there a way to force the control to redraw?

Is there an event that fires when the control can accept re-positioning?

 

 

Hi Kenneth,

I will need some time to check on your scenario. I will contact you as soon as I have more information on the matter.

Regards,
Martin
Telerik

Hello Kenneth,

I am not sure that I completely understand your case. This is why I would ask you to send me a runnable code that demonstrates your implementation and the position change with the 1/2 sec delay behavior, so I can test it locally and get better understanding of your scenario.

About the event related to positioning you can use TilesPositionChanged event. As for redrawing the control you can try to call its UpdateLayout() method in the tileview's TilesPositionChanged event handler. You can also try to call the Measure() and Arrange() methods before the UpdateLayout(). 

Regards,
Martin
Telerik

I have a sample app for you to look at but I don't know how to upload the zip file,  it gives error only jpg, gif...etc

So posting here

 Here is the xaml

 

here is the code behing

Addendum:  Visibility/Collapsed of individual tiles does not ​have anything to do with recreating the problem as I first thought.  Is seem that while the control is initializing it is ignoring tile positioning from code behind, once it is fully initialized everything works as expected.  My problem is I don't know when it is done 'initializing'.  I have animation off so annimationcompleted never fires.  TilePositionChanged does fire, once for each tile on load, so this code does work, but it is only a slight improvement over the timer, in that I need to know the order the tiles load and move tiles only after they have been initially positioned.

Here is my solution, it's not terrible.  Maintain a flag indicating first time initialization is in progress.  Once the last tile in xaml is positioned then set tiles to desired position and turn off flag

 code

 

xaml 

 

comment in code above should read: this is honored.

comment in above code should read: this is honored.

My proposed solution does not work for me in the production project.  The reason is that the last tile is often collapsed so its position changed event never fires.  I ​forced it to be ​visible but for some reason I have not tracked down yet the event still does not fire, something beforehand must be collapsing it.  I considered having a dummy last tile that was always visible until it got re-positioned then hiding it but this introduces a lot of odd complexity in the code because of the way I'm tracking the position and visibility of the tiles (in an integer array that needs to have the same number of elements as there are tiles).  I can't find a reliable indicator as to when it is okay to position tiles.

Hi Kenneth,

Thank you for the code snippets. I can confirm that the tileview items' Position setting is not respected until the tiles are generated. This behavior in RadTileView is expected since the position setting requires the item to has its ParentTileView set which happens on the tile's generation.

In order to set the Position of a specific item on load of the control you can use couple approaches:

• Subscribe for the RadTileView's Loaded event and set the tile's Position in Dispatcher.
  
  Private Sub TileView_Loaded(sender As Object, e As RoutedEventArgs)

      Dispatcher.BeginInvoke(New Action(Function()

         Me.Tile2.Position = 0 

        End Function))

  End Sub
• Or you can subscribe for the StatusChanged event of the ItemContainerGenerator of the tileview and listen for the "ContainersGenerated" status. If the containers are generated set the position.
  
  ' subscribe for the Me.TileView.ItemContainerGenerator's StatusChanged event

  '---------------------------------

  Private Sub ItemContainerGenerator_StatusChanged(sender As Object, e As EventArgs)

      Dim generator As ItemContainerGenerator = TryCast(sender, ItemContainerGenerator)

      If generator.Status = System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated Then

          Me.Tile2.Position = 0

      End If

  End Sub

Please try this and let me know if it works for you.

Regards,
Martin
Telerik