How do I show a Save As dialog in WPF?

Question

I have a requirement in WPF/C# to click on a button, gather some data and then put it in a text file that the user can download to their machine. I can get the first half of

Answer 1

All the examples so far use the Win32 namespace, but there is an alternative:

FileInfo file = new FileInfo("image.jpg");
var dialog = new System.Windows.Forms.SaveFileDialog();
dialog.FileName = file.Name;
dialog.DefaultExt = file.Extension;
dialog.Filter = string.Format("{0} images ({1})|*{1}|All files (*.*)|*.*",
    file.Extension.Substring(1).Capitalize(),
    file.Extension);
dialog.InitialDirectory = file.DirectoryName;

System.Windows.Forms.DialogResult result = dialog.ShowDialog(this.GetIWin32Window());
if (result == System.Windows.Forms.DialogResult.OK)
{

}

I'm using an extension method to get the IWin32Window from the visual control:

#region Get Win32 Handle from control
public static System.Windows.Forms.IWin32Window GetIWin32Window(this System.Windows.Media.Visual visual)
{
    var source = System.Windows.PresentationSource.FromVisual(visual) as System.Windows.Interop.HwndSource;
    System.Windows.Forms.IWin32Window win = new OldWindow(source.Handle);
    return win;
}

private class OldWindow : System.Windows.Forms.IWin32Window
{
    private readonly System.IntPtr _handle;
    public OldWindow(System.IntPtr handle)
    {
        _handle = handle;
    }

    System.IntPtr System.Windows.Forms.IWin32Window.Handle
    {
        get { return _handle; }
    }
}
#endregion

Capitalize() is also an extension method, but not worth mentioning as there are plenty of examples of capitalizing the first letter of a string out there.