Question

I’m just starting to develop the Winforms GUI for a C# application and was wondering if the following was possible?

I wish to display a large image in a Picture Box (easily done) and then have a second smaller image overlay onto the large image at the mouse position, when the mouse pointer is over the larger image. If possible I would like the overlay image to be partially transparent.

As the GUI design is at an early stage I can change it to WPF if this would make what I’m asking any easier.

Many thanks,

Andy.

Answer 1

That’s a one-liner in Winforms, just change the PictureBox.Cursor property:

 pictureBox1.Cursor = new Cursor(new MemoryStream(Properties.Resources.ExampleCursor));

If you need an arbitrary image then you need to convert the bitmap to a cursor. A little helper function to do it:

using System.Reflection;
...
    private static Cursor CursorFromBitmap(Bitmap bmp) {
        var hicon = bmp.GetHicon();
        var cursor = new Cursor(hicon);
        var fi = typeof(Cursor).GetField("ownHandle", BindingFlags.NonPublic | BindingFlags.Instance);
        fi.SetValue(cursor, true);
        return cursor;
    }

With some reflection trickery to avoid having to keep track of the handle and destroy it explicitly. Use it like this:

 pictureBox1.Cursor = CursorFromBitmap(Properties.Resources.ExampleImage);