why doesn't this DrawLine code do anything?

[RichGK]

This is from

http://msdn2.microsoft.com/en-us/library/aa287522(VS.71).aspx

public MainForm()
{
InitializeComponent();


System.Drawing.Pen myPen;
myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
System.Drawing.Graphics formGraphics = this.CreateGraphics();
formGraphics.DrawLine(myPen, 0, 0, 500, 500);
myPen.Dispose();
formGraphics.Dispose();
}

Sorry about the formatting, google is terrible at allowing tabs.

 

[Christof Nordiek]

Hi,

actually the code does something, but the Line is deleted while the next
Paint event.
You should put this code into the OnPaint method.

 

[Didier Bolf]

a paint event erase what you draw in the contructor

public Form1()
{
InitializeComponent();
Paint += new PaintEventHandler(Form1_Paint);
}
void Form1_Paint(object sender, PaintEventArgs e)
{
System.Drawing.Pen myPen;
myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
System.Drawing.Graphics formGraphics = this.CreateGraphics();
formGraphics.DrawLine(myPen, 0, 0, 500, 500);
myPen.Dispose();
formGraphics.Dispose();
}