How can I change a label background color in a WPF form, by clicking a button in a WinForms form?

Question

In my program I have two windows opened at the same time, one is a WPF form and the other one is a WinForms form.

I need to change a label background color that's on a WPF form, by clicking a button that's placed on the WinForms form.

How can I do it?

Answer 1

You could set up an EventHandler to publish an event notification when the Button control in your WinForms form is pressed. This event would be monitored by your WPF Window/UserControl to detect when the event is triggered and then request the desired color to set your WPF Label to.

MainWindow.xaml

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"
        Title="MainWindow" Height="150" Width="225">
    <Grid>
        <Label Content="Label" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Height="100" Width="197" Background="{Binding LabelBgColour}"/>
    </Grid>
</Window>

MainWindow.xaml.cs

namespace WpfApplication1
{
    using System.Windows;
    using System.ComponentModel;
    using System.Windows.Media;

    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        public MainWindow()
        {
            InitializeComponent();
            var f = new Form1();
            f.ChangedColourEventHandler += TriggeredChangedColourEventHandler;
            f.Show();
        }

        private Brush labelBgColour;
        public Brush LabelBgColour
        {
            get
            {
                return this.labelBgColour;
            }
            set
            {
                this.labelBgColour = value;
                OnPropertyChanged();
            }
        }

        private void TriggeredChangedColourEventHandler(object sender, Brush color)
        {
            this.LabelBgColour = color;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName = null)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}

Form1.cs

namespace WpfApplication1
{
    using System;
    using System.Windows.Forms;
    using System.Windows.Media;

    public partial class Form1 : Form
    {
        public EventHandler<Brush> ChangedColourEventHandler;

        public Form1()
        {
            InitializeComponent();
        }

        private Brush bgColour;
        private Brush BgColour
        {
            get
            {
                return this.bgColour;
            }
            set
            {
                this.bgColour = value;
                TriggerChangedColourEventHandler(value);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.BgColour = (Brush)new BrushConverter().ConvertFromString("#FF00B25A");
        }

        private void TriggerChangedColourEventHandler(Brush color)
        {
            var handler = ChangedColourEventHandler;
            if (handler != null)
            {
                handler(this, color);
            }
        }
    }
}

Form1 has a single Button control named button1 (as can be determined from the example cs). I have omitted the Form1.Design.cs for brevity.

This example has the WPF window go to the WinForm to get the desired Color value. It could be easily adapted so that the Color value is sent as part of the EventHandler event (EventArgs).

Answer 2

I'm sure there are a lot of ways to achieve this. Some smaller and more obscure and some more longwinded but more clear.

Like you could do something through the win32 api, communicate through a memory-mapped file or use some form off communication transport like NamedPipes or MSMQ.

You can look at some of these resources for ideas:

• How can I invoke a method within another process instance of my WinForms app?

• Example of Named Pipes

Best of luck! :)

Answer 3

Assuming that the Winform object is available in WPF form and the Button1 is public, you need to add code similar to below in the WPF form.

WinForm.Button1.Click += new System.EventHandler(Button1_Click);

private void Button1_Click(object sender, EventArgs e)
{
// Change label background
}