Creating a WPF Custom Control in Windows Form but with Error message : Make sure the type has a default constructor

Question

I am creating a custom WPF control in windows form for a temperature dial in vb.net. When I try to add the WPF control in windows form using ElementHost, I Get the error message "". And yes I have added WindowsFormsIntegration.dll to my project's references.

I have attached the code and WPF control Image.

Please help me to resolve the issue.

Thank you in advance

Answer 1

I followed the link you sent and used the steps and code below to run the program successfully.

1. Create a new Windows Forms project.
2. Add the WPF User Control Library project to the solution.
3. Create a new WPF user control to the WPF User Control Library project.
4. Add a reference to the WPF User Control Library from the Windows Forms project.
5. Also add a reference to the WindowsFormsIntegration.dll and PresentationCore.dll assemblies from the Windows Forms project.
6. Create an ElementHost object and an instance of the UserControl in the Windows Forms application and set the Child property of the ElementHost control to the UserControl instance. Finally, add the ElementHost object to the Controls collection of the form.

The code of UserControl.xaml (WPF User Control Library project):

<UserControl x:Class="UserControl1"  
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"   
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"   
             xmlns:local="clr-namespace:WpfControlLibrary1"  
             mc:Ignorable="d"   
             d:DesignHeight="450" d:DesignWidth="450">  
    <Viewbox>  
        <Grid>  
            <Ellipse Name="gauge" HorizontalAlignment="Left" Height="400"  StrokeThickness="10" Margin="23,25,0,0" Stroke="Black" VerticalAlignment="Top" Width="400">  
                <Ellipse.Fill>  
                    <RadialGradientBrush>  
                        <GradientStop Color="Black" Offset="1"/>  
                        <GradientStop Color="White"/>  
                    </RadialGradientBrush>  
                </Ellipse.Fill>  
            </Ellipse>  
            <Ellipse HorizontalAlignment="Left" Height="49" StrokeThickness="0" Margin="205,205,0,0" Stroke="Black" VerticalAlignment="Top" Width="45" RenderTransformOrigin="0.274,0.252">  
                <Ellipse.Fill>  
                    <RadialGradientBrush>  
                        <GradientStop Color="Black" Offset="1"/>  
                        <GradientStop Color="White"/>  
                    </RadialGradientBrush>  
                </Ellipse.Fill>  
            </Ellipse>  
            <Rectangle Name="Needle" HorizontalAlignment="Left" Height="188" Margin="220,71,0,0"  VerticalAlignment="Top" Width="13" >  
                <Rectangle.Fill>  
                    <ImageBrush >  
                        <ImageBrush.ImageSource>  
                            <BitmapImage UriSource="rr.jpg"/>  
                        </ImageBrush.ImageSource>  
                    </ImageBrush>  
                </Rectangle.Fill>  
            </Rectangle>  

        </Grid>  
    </Viewbox>  
</UserControl>  

The code of UserControl.xaml.vb:

Imports System.Windows.Media  

Partial Public Class UserControl1  
    Inherits System.Windows.Controls.UserControl  

    Public pointerValue As Double  

    Public Sub New()  
        InitializeComponent()  
    End Sub  

    Public Sub changevalue()  
        Dim rotate As RotateTransform = New RotateTransform(pointerValue)  
        Needle.RenderTransform = rotate  
    End Sub  
End Class  

Add a reference of WpfControlLibrary1 to WindowsApp1:

The designer of Form1.vb:

The code of Form1.vb:

Imports System.Windows.Forms.Integration  
Imports WpfControlLibrary1  

Public Class Form1  
    Private gauge As UserControl1  
    Private host As ElementHost  
    Public Sub New()  
        InitializeComponent()  
        gauge = New UserControl1()  
        host = New ElementHost()  
        host.Dock = DockStyle.Fill  
        host.Child = gauge  
        Me.Controls.Add(host)  

    End Sub  
    Private value As Integer  
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click  
        gauge.changevalue()  
        Integer.TryParse(valuepointer.Text, value)  
        gauge.pointerValue = value  
    End Sub  
End Class  

The picture of result:

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