How to make a control in XAML public in order to be seen in other classes

Using the following XML you can define a control as a public field on the class to be able to access it from other classes:

<CheckBox x:Name="myCheckBox" x:FieldModifier="public" />

Now you can access the field directly in code:

if (win.myCheckBox.IsChecked.Value){    // ...}

I agree with H.B., though, that using the MVVM pattern is a better way to do it. Other parts of your code shouldn't be aware of your UI or directly access it.

EDIT:

With the MVVM approach you should first define your view model class:

public class ViewModel{    public bool IsChecked { get; set; }}

Then you set an instance of this class as DataContext:

• either in code, e.g. window constructor:

public MyWindow(){    InitializeComponent();    DataContext = new ViewModel();}

• or in XAML, e.g. App.xaml:

<Application x:Class="WpfApplication2.App"             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"             xmlns:vm="clr-namespace:WpfApplication2"             StartupUri="MainWindow.xaml">    <Application.Resources>        <vm:ViewModel x:Key="ViewModel" />    </Application.Resources></Application>

Now you can bind your CheckBox to a property in ViewModel:

<CheckBox IsChecked="{Binding IsChecked, Mode=TwoWay}" />

All that's left is to pass the ViewModel instance to your OnRender function. It is stored in the DataContext property of your window.

EDIT 2:

BTW: You really should have asked that before you accepted the answer.

I'm not sure what you are trying to attempt with the is_clicked property. To set this flag when the button is clicked, you need a Command:

public class CalibrateCommand : ICommand{    private ViewModel viewModel;    public CalibrateCommand(ViewModel viewModel)    {        this.viewModel = viewModel;    }    public void Execute(object parameter)    {        viewModel.IsClicked = true;    }    public bool CanExecute()    {        return true;    }}

You add an instance of this command to your view model:

public class ViewModel{    public bool IsChecked { get; set; }    public bool IsClicked { get; set; }    public ICommand CalibrateCommand { get; set; }    public ViewModel()    {        CalibrateCommand = new CalibrateCommand(this);    }}

You bind it to the button like this:

<Button Content="Calibrate" Height="24" x:Name="Calibrate" x:FieldModifier="public" Width="90" Click="Calibrate_Click" HorizontalContentAlignment="Center" VerticalContentAlignment="Center" HorizontalAlignment="Left" DockPanel.Dock="Left" Panel.ZIndex="0" Padding="0" VerticalAlignment="Center" Command="{Binding CalibrateCommand}" />

You don't need to handle any events of the CheckBox and the Button, everything is handled by the binding.

If you added a dependency property to KinectSkeleton you should bind it to the view model:

<kt:KinectSkeleton ViewModelH="{Binding}" />

Don't make the checkbox visible to the outside, just pass the current state of the checkbox to the function or class. Also consider binding the checkbox value to a class in the DataContext, directly accessing controls can be avoided most of the time in WPF, see also the MVVM pattern.