How to display a PictureBox from behind code in C#

Since the PictureBox that you are using is a Winforms Control you will need to add a WindowsFormsHost Control to your Wpf Form and add the PictureBox to that. Any time you dynamically create a control you need to add it to the Form or Container object otherwise it will not be shown.

But first, add these references:

System.Windows.Forms
WindowsFormsIntegration

Now write code something like this.

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"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <WindowsFormsHost Height="175" HorizontalAlignment="Left" Margin="10,10,0,0" Name="windowsFormsHost1" VerticalAlignment="Top" Width="255" />
    </Grid>
</Window>

MainWindow.xaml.cs

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            System.Windows.Forms.PictureBox picturebox1 = new System.Windows.Forms.PictureBox();
            windowsFormsHost1.Child = picturebox1;
            picturebox1.Paint += new System.Windows.Forms.PaintEventHandler(picturebox1_Paint);
        }

        void picturebox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
        {
            System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(@"C:\Temp\test.jpg");
            System.Drawing.Point ulPoint = new System.Drawing.Point(0, 0);
            e.Graphics.DrawImage(bmp,ulPoint);
        }
    }
}