Dynamically change cursor size in c#

Question

I created a .cur file with a simple cursor filled ellipse inside.

I wish this Cursor to act like a "Brush Cursor" meaning that if I change thickness of the brush, the size of the Cursor will change (I would also like to change the color of the Cursor).

Here's the code I'm using:

var customCursor = new Cursor(@"CustomCursor.cur");
Mouse.OverrideCursor = currentCursor;

Can such thing be done? Is there any better way to do it?

Answer 1

I've used this before, and it works.

Cursor CreateCursor(double rx, double ry, SolidColorBrush brush, Pen pen)
{
    var vis = new DrawingVisual();
    using (var dc = vis.RenderOpen())
    {
        dc.DrawRectangle(brush, new Pen(Brushes.Black, 0.1), new Rect(0, 0, rx, ry));
        dc.Close();
    }
    var rtb = new RenderTargetBitmap(64, 64, 96, 96, PixelFormats.Pbgra32);
    rtb.Render(vis);

    using (var ms1 = new MemoryStream())
    {
        var penc = new PngBitmapEncoder();
        penc.Frames.Add(BitmapFrame.Create(rtb));
        penc.Save(ms1);

        var pngBytes = ms1.ToArray();
        var size = pngBytes.GetLength(0);

        //.cur format spec http://en.wikipedia.org/wiki/ICO_(file_format)
        using (var ms = new MemoryStream())
        {
            {//ICONDIR Structure
                ms.Write(BitConverter.GetBytes((Int16)0), 0, 2);//Reserved must be zero; 2 bytes
                ms.Write(BitConverter.GetBytes((Int16)2), 0, 2);//image type 1 = ico 2 = cur; 2 bytes
                ms.Write(BitConverter.GetBytes((Int16)1), 0, 2);//number of images; 2 bytes
            }

            {//ICONDIRENTRY structure
                ms.WriteByte(32); //image width in pixels
                ms.WriteByte(32); //image height in pixels

                ms.WriteByte(0); //Number of Colors in the color palette. Should be 0 if the image doesn't use a color palette
                ms.WriteByte(0); //reserved must be 0

                ms.Write(BitConverter.GetBytes((Int16)(rx / 2.0)), 0, 2);//2 bytes. In CUR format: Specifies the horizontal coordinates of the hotspot in number of pixels from the left.
                ms.Write(BitConverter.GetBytes((Int16)(ry / 2.0)), 0, 2);//2 bytes. In CUR format: Specifies the vertical coordinates of the hotspot in number of pixels from the top.

                ms.Write(BitConverter.GetBytes(size), 0, 4);//Specifies the size of the image's data in bytes
                ms.Write(BitConverter.GetBytes((Int32)22), 0, 4);//Specifies the offset of BMP or PNG data from the beginning of the ICO/CUR file
            }

            ms.Write(pngBytes, 0, size);//write the png data.
            ms.Seek(0, SeekOrigin.Begin);
            return new Cursor(ms);
        }
    }
}

Then, to set it, you call:

  Mouse.OverrideCursor = CreateCursor(50,50, Brushes.Gold, null);

Source: https://gist.github.com/kip9000/4201899