Rank 1
Hey,
How can we apply a different Template for the selected item?
Thanks,
Mano
2 Answers, 1 is accepted
The RadListView provides styles; ItemStyle, SelectedItemStyle and PressedItemStyle. See the following documentation for guidance: Item Styles. You can even use a StyleSelector to choose a different style depending on a predefined condition, see ItemStyle Selector documentation.
If you're referring to having a completely different ItemTemplate, almost no ListView type of object provide different DataTemplate-based properties on the condition of selection. You'll instead need to create a Xamarin.Forms.DataTemplateSelector object and assign it to the RadLstView.ItemTemplateSelector property. We have a tutorial on how to accomplish this in the following article: ItemTemplateSelector.
Once you've read that tutorial and are famliar with using a DataTemplateSelector, lets move on to the relevancy to changing a template based on selection.
First, you'll need to sync a model boolean property to your data model if there isn't one yet (make sure you invoke PropertyChanged for this property):
public class Student : NotifyPropertyChangedBase{ public string Title { get; set; } private bool _isItemSelected; public bool IsItemSelected { get => _isItemSelected; set { if(_isItemSelected == value) return; _isItemSelected = value; OnPropertyChanged(); } }}Then, subscribe to the SelectionChanged event of the RadListView and toggle the data item's selected flag accordingly:
private void RadListView_SelectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e){ if (e.OldItems != null) { foreach (var item in e.OldItems) { (item as Student).IsItemSelected = false; } } if (e.NewItems != null) { foreach (var item in e.NewItems) { (item as Student).IsItemSelected = true; } }}Finally, in the template selector, you can use this value to return the appropriate DataTemplate:
public class MyItemTemplateSelector : DataTemplateSelector{ public DataTemplate RegularTemplate { get; set; } public DataTemplate SelectedTemplate { get; set; } protected override DataTemplate OnSelectTemplate(object item, BindableObject container) { if (item is Student student) { return student.IsItemSelected ? SelectedTemplate : RegularTemplate; } return null; }}Regards,
Lance | Tech Support Engineer, Sr.
Progress Telerik
Rank 1
Thanks!
It looks like this code is getting what I need:
protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
{
RadListView listView = container as RadListView;
if (listView == null)
return RegularTemplate;
if (listView.SelectionMode == SelectionMode.Single)
return listView.SelectedItem != null && listView.SelectedItem == item ? SelectedTemplate : RegularTemplate;
else if (listView.SelectionMode == SelectionMode.Multiple)
return listView.SelectedItems.Contains(item) ? SelectedTemplate : RegularTemplate;
else
return RegularTemplate;
}