crosshair tool, is there one? Visual studio 2008

I am doing some image sampling. What my question is, is there a 'crosshair' tool in visual studio? I want to have several instances on a single form, be able to move them around and then sample those points, obviously returning the color of the pixel at the center of the crosshair, is 开发者_运维问答there already a tool that will do this, before I go and write one?

Thanks, R.

I know of no crosshair, but the following procedure can be used twice to draw a crosshair. To remove it, simply draw it again as it uses XOR to make the procedure reversible.

ControlPaint.DrawReversibleLine().

You could just change the cursor:

    private void btnSample_Click(object sender, EventArgs e) {
        this.Cursor = Cursors.Cross;
    }
    protected override void OnMouseDown(MouseEventArgs e) {
        if (this.Cursor == Cursors.Cross) {
            this.Cursor = Cursors.Default;
            // etc...
        }
    }

I would change the cursor to Cursor.cross. Then just paint indicators at the mousedown-points with GDI on the PictureBox's Graphic, sample the colors from those locations and then clear the PictureBox's Graphic when the operation is done.