/// <summary>
/// Creates system-style buttons if requested and hooks up CanExecuteChanged for the ToolbarItem command.
/// (after writing this I noticed that the latter will be in the next version of Forms... oh well)
/// </summary>
/// <param name="toolbarItem"></param>
/// <returns></returns>
private UIBarButtonItem CreateUIBarButtonItem(ToolbarItemEx toolbarItem)
{
UIBarButtonSystemItem? systemItem = null;
switch (toolbarItem.ToolbarItemType)
{
case ToolbarItemType.Done:
systemItem = UIBarButtonSystemItem.Done;
break;
case ToolbarItemType.Add:
systemItem = UIBarButtonSystemItem.Add;
break;
}
var buttonItem = systemItem != null ? new UIBarButtonItem(systemItem.Value, (s, e) => toolbarItem.Activate()) : toolbarItem.ToUIBarButtonItem();
// Xamarin.Forms 1.3.2 adds support for CanExecute, so we only need this for
// our custom system buttons
//
if (systemItem != null)
{
var command = toolbarItem.Command;
EventHandler canExecuteHandler = (s, e) => UpdateButtonState(toolbarItem, buttonItem);
command.CanExecuteChanged += canExecuteHandler;
toolbarItem.PropertyChanged += (s, e) =>
{
if (e.PropertyName == ToolbarItem.CommandProperty.PropertyName)
{
command.CanExecuteChanged -= canExecuteHandler;
UpdateButtonState(toolbarItem, buttonItem);
toolbarItem.Command.CanExecuteChanged += canExecuteHandler;
}
};
UpdateButtonState(toolbarItem, buttonItem);
}
return buttonItem;
}
private static void UpdateButtonState(ToolbarItemEx toolbarItem, UIBarButtonItem buttonItem)
{
buttonItem.Enabled = toolbarItem.Command.CanExecute(toolbarItem.CommandParameter);
}
