Draw line rotated at an angle over bitmap

Question

I am drawing a line from centre of png image to top in below code:

    private string ProcessImage(string fileIn)
    {
        var sourceImage = System.Drawing.         


        

Answer 1

Let's assume you have the angle you want in a float angle all you need to do is to insert these three lines before drawing the line:

    g.TranslateTransform(x, y);   // move the origin to the rotation point 
    g.RotateTransform(angle);     // rotate
    g.TranslateTransform(-x, -y); // move back

    g.DrawLine(new Pen(Color.Black, (float)5), new Point(x, 0), new Point(x, y));

If you want to draw more stuff without the rotation call g.ResetTranform() !