如何通过用户在C＃Windows窗体中选择四个坐标点来绘制矩形并在文本框中显示坐标点

Question

In my c# windows form application I am trying to draw a rectangle by getting the coordinates from the user through 4 mouse click events in the windows form, one for each point.

Here is what I've tried so far.

private void Form1_Click(object sender, EventArgs e)
{
    using (Graphics g = this.CreateGraphics())
    {
        Pen pen = new Pen(Color.Black, 2);
        Brush brush = new SolidBrush(this.BackColor);
        g.FillRectangle(brush, this.Bounds);  // redraws background
        g.DrawRectangle(pen,textBox1.Text,textBox2.Text,textBox3.Text,textBox4.Text);
        pen.Dispose();
        brush.Dispose();
    }
}    

Answer 1

Your first mistake is drawing in a Click handler. Don't use CreateGraphics . Anything you draw with that is volatile and unlikely to play well.

What you should do is collect the points you want to draw when the Click event fires. Add a handler for the form's Paint event and do your drawing there. The event args will provide a Graphics object for you to use.

A separate method for calculating the rectangle might also be useful to keep that work out of the Paint handler.