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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;
using Tango.AutoComplete.Editors;
using Tango.SharedUI;
public static class ViewModelExtensionMethods
{
/// <summary>
/// Sets the focus to the visual element that binds to the specified property.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="vm">The view model.</param>
/// <param name="propertyLambda">The property lambda.</param>
public static void SetFocus<T>(this ViewModel vm, Expression<Func<T>> propertyLambda)
{
var me = propertyLambda.Body as MemberExpression;
SetFocus(vm, me.Member.Name);
}
/// <summary>
/// Sets the focus to the visual element that binds to the specified property.
/// </summary>
/// <param name="vm">The view model.</param>
/// <param name="propertyName">The property name.</param>
public static void SetFocus(this ViewModel vm, string propertyName)
{
Application.Current.Dispatcher.BeginInvoke(new Action(async () =>
{
await Task.Delay(200);
var control = GetUserControl(vm, Application.Current.MainWindow);
if (control != null)
{
var element = FindElementByPropertyName(vm, control, propertyName);
if (element != null)
{
element.Focusable = true;
Keyboard.Focus(element);
}
else
{
Debug.WriteLine($"SetFocus: {propertyName} not found!");
}
}
else
{
Debug.WriteLine($"SetFocus: {propertyName} not found!");
}
}), DispatcherPriority.ApplicationIdle);
}
private static UserControl GetUserControl(ViewModel vm, FrameworkElement parent)
{
var children = parent.FindVisualChildren<UserControl>();
foreach (var child in children)
{
if (child.DataContext == vm)
{
return child;
}
else
{
var innerChild = GetUserControl(vm, child);
if (innerChild != null)
{
return innerChild;
}
}
}
return null;
}
private static FrameworkElement FindElementByPropertyName(ViewModel vm, FrameworkElement parent, string propName)
{
FrameworkElement foundChild = null;
var children = LogicalTreeHelper.GetChildren(parent).OfType<FrameworkElement>().ToList();
int count = VisualTreeHelper.GetChildrenCount(parent);
for (int i = 0; i < count; i++)
{
var child = VisualTreeHelper.GetChild(parent, i) as FrameworkElement;
if (child != null)
{
children.Add(child);
}
}
children = children.Distinct().ToList();
foreach (var child in children)
{
if (child.DataContext == vm)
{
BindingExpression bindingExpression = child.GetBindingExpression(TextBox.TextProperty);
if (bindingExpression == null)
{
bindingExpression = child.GetBindingExpression(Button.CommandProperty);
}
if (bindingExpression == null)
{
bindingExpression = child.GetBindingExpression(Tango.SharedUI.Helpers.PasswordHelper.PasswordProperty);
}
if (bindingExpression == null)
{
bindingExpression = child.GetBindingExpression(AutoCompleteTextBox.SelectedItemProperty);
}
if (bindingExpression != null)
{
if (bindingExpression.ResolvedSourcePropertyName == propName)
{
return child;
}
}
}
foundChild = FindElementByPropertyName(vm, child, propName);
if (foundChild != null)
{
return foundChild;
}
}
return foundChild;
}
}
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