draw rich text in a custom control

[Duong Tien Nam]

I'm writing a control similar to visio to draw shapes and text, now I want to support rich text drawing into my control. I searched the web and found what they call "windowless rich text control" but it does not have code for C#, below is what I tried to do but it is not work:

namespace WindowsFormsApplication1
{
[Guid("c5bdd8d0-d26e-11ce-a89d-00aa006cadc5")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface ITextHost
{
IntPtr TxGetDC();
IntPtr TxReleaseDC(IntPtr hdc);
}

public partial class Form1 : Form, ITextHost
{
    \[DllImport("riched20.dll")\]
    private static extern int CreateTextServices(
      \[MarshalAs(UnmanagedType.IUnknown)\] object punkOuter,
      ITextHost pITextHost,
      \[MarshalAs(UnmanagedType.IUnknown), Out\] out object ppUnk);

    public Form1()
    {
        InitializeComponent();
        this.Load += new EventHandler(Form1\_Load);
    }

    void Form1\_Load(object sender, EventArgs e)
    {
        object ppUnk = null;
        int result = CreateTextServices(null, this, out ppUnk);
    }

    #region ITextHost Members

    public IntPtr TxGetDC()
    {
        return this.Handle;
    }

    public IntPtr TxReleaseDC(IntPtr hdc)
    {
        return IntPtr.Zero;
    }
}

}

When run into the method CreateTextServices, it keeps saying that the memory is corrupted. I don't know what I did wrong in the code. And I stuck with it. Please help me with that, thanks for your concern.

[Jimmanuel]

Have you seen the Graphics[^] class? If you handle the OnPaint event of a control you can use it to draw anything you want on it. :badger: