public void Update(Layout <View> layout)
{
var mode = OptionButtons.GetSelectionMode(layout);
if (mode == SelectionMode.None)
{
foreach (var child in layout.Children)
{
if (child is Button button)
{
button.Clicked -= OnButtonClicked;
}
}
layout.ChildAdded -= OnChildAdded;
layout.ChildRemoved -= OnChildRemoved;
isSubscribed = false;
}
else if (!isSubscribed)
{
foreach (var child in layout.Children)
{
if (child is Button button)
{
button.Clicked += OnButtonClicked;
}
}
layout.ChildAdded += OnChildAdded;
layout.ChildRemoved += OnChildRemoved;
isSubscribed = true;
}
UpdateSelection(layout);
}
private static void UpdateSelection(Layout <View> layout)
{
var mode = OptionButtons.GetSelectionMode(layout);
var allowNone = OptionButtons.GetAllowNone(layout);
var selectedItems = OptionButtons.GetSelectedItems(layout);
var selectedItem = OptionButtons.GetSelectedItem(layout);
for (var i = 0; i < layout.Children.Count; i++)
{
var child = (View?)layout.Children[i];
if (child is Button button && child.BindingContext is object item)
{
if (mode == SelectionMode.Multiple)
{
if (selectedItems?.Contains(item) == true)
{
VisualStateManager.GoToState(button, SelectedState);
}
else
{
VisualStateManager.GoToState(button, UnselectedState);
}
}
else if (mode == SelectionMode.Single)
{
if (selectedItem == item)
{
VisualStateManager.GoToState(button, SelectedState);
}
else
{
VisualStateManager.GoToState(button, UnselectedState);
}
}
}
}
}
private static void OnButtonClicked(object sender, EventArgs e)
{
if (!(sender is Button button) ||
!(button?.Parent is Layout <View> parent) ||
!(button.BindingContext is object item))
{
return;
}
var mode = OptionButtons.GetSelectionMode(parent);
if (mode == SelectionMode.None)
{
return;
}
var allowNone = OptionButtons.GetAllowNone(parent);
var selectedItems = OptionButtons.GetSelectedItems(parent);
if (!allowNone)
{
if (selectedItems != null)
{
// do not unselect a single item if we are not allowed
if (selectedItems.Count == 1 && item.Equals(selectedItems[0]))
{
return;
}
}
}
// clear the list if we are not a multi-select list
if (mode != SelectionMode.Multiple)
{
if (selectedItems != null)
{
for (var i = selectedItems.Count - 1; i >= 0; i--)
{
if (selectedItems[i] == item)
{
i--;
}
else
{
selectedItems.RemoveAt(i);
}
}
}
foreach (var btn in parent.Children)
{
if (btn != button)
{
VisualStateManager.GoToState(btn, UnselectedState);
}
}
}
var shouldSelect = false;
// update the selected items list
if (selectedItems != null)
{
shouldSelect = !selectedItems.Contains(item);
if (shouldSelect)
{
selectedItems.Add(item);
}
else
{
selectedItems.Remove(item);
}
}
// updated the selected item
OptionButtons.SetSelectedItem(parent, item);
VisualStateManager.GoToState(button, shouldSelect ? SelectedState : UnselectedState);
}
