Getting Form coordinates within class

Question

Basically I have created a Class with a method that is called everytime there is a click on my form(it is supposed to draw a single line where I clicked) it goes as follows:

public void Dessiner(Graphics Fg)
{

    Point p = Form1.MousePosition;
    Fg.DrawLine(MyPen,p.X,p.Y,p.X+2,p.Y+2);
}

The problem is when I call this method within my Forms' mousedown event it places the line at the wrong spot everytime.

Notes: the method can only take the graphics Fg, and the drawing of the line MUST be done within the method of the class.

What am I doing wrong?

Answer 1

You need to transform the coordinates with PointToClient()

public partial class Form1 : Form
{
    DrawingHelper dh;
    public Form1()
    {
        InitializeComponent();

        dh=new DrawingHelper(this);

    }

    private void Form1_MouseDown(object sender, MouseEventArgs e)
    {
        dh.Desser(this.CreateGraphics());
    }
}

public class DrawingHelper
{
    Form form;
    public DrawingHelper(Form form)
    {
        this.form  =form;
    }
    public void Desser(Graphics Fg)
    {
        var pt=form.PointToClient(Form.MousePosition);
        Fg.DrawLine(Pens.Black, pt.X,pt.Y, pt.X+2, pt.Y+2);
    }
}