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Draw a Line over child control such PictureBox or Group Box using C#

Hi Experts,

How do I draw line over a control ?
Let say like this, I have a Windows Forms, and top of it there are GroupBox and on top of GroupBox there are PictureBox.
And how do I draw a line over GroupBox and PictureBox ?

bungHoc

Try this:

System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Red);
 
System.Drawing.Graphics formGraphics;
formGraphics = this.CreateGraphics();
formGraphics.DrawLine(pen, 50, 50, 100, 100);
pen.Dispose();
formGraphics.Dispose();

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Jaime Olivares

Maybe these controls fit your needs:
http://www.codeproject.com/useritems/Line_Control.asp
http://www.codeproject.com/cs/miscctrl/csLineControlWithRotateOp.asp

ASKER CERTIFIED SOLUTION

Mike Tomlinson

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Aryo1

ASKER

@Idle_Mind

Thx, it seems your solutions can answers my problems.

BTW, Do you have suggestion where should I put this code ?
On Form_Paint or everytime there is change in UI (such as moving some control) ?

Mike Tomlinson

Well...a "catch all" approach would be to use the IMessageFilter() Interface and repaint the line whenever ANY control in your app gets a WM_PAINT message. If your app is partially obscured though you could end up drawing a line over another apps window since we are drawing with the desktop DC.

Here is an example of IMessageFilter being used:
https://www.experts-exchange.com/questions/22696110/Move-label-with-cursor-location.html