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Draw a line on form using Graphics class in vb.net - C #.net.

Author: Maliha Atteeq
Download Source Code : 1017_lineDraw.zip

In this simple article you will learn that how to draw a line on the form using Graphics class in vb and C #.net.

 Graphics:

This is the very important class for making graphics of your own using c#. This class cannot be inherited. This class provides us a number of different methods for graphics creation. By using these methods you can create graphics of your own choice.

In this article I will tell you that how can we draw a line using system.drawing.graphics.

Line draw:

In order to draw a line on the form, firstly you should know the behavior of the form. While playing with the graphics you must keep the following point in your mind:

 You can’t draw graphics on simple load event of the form. To create graphics on the form, you must override the onpaint() function of the form.

The syntax of the onpaint() function is:

C#:

protected override void OnPaint (PaintEventArgs e)

{

}

VB:

Dim e As PaintEventArgs

 

Me.OnPaint(e)

Line’s draw function:

In order to draw a line, graphics class provides us a function named as drawLine(). It is an overloaded function. By using this function you can draw a line on the form. Depending on your requirement you can use any of the overloaded function. I use the following:

This function takes three arguments. The first argument is the object of Pen class. Pen class has the four overloaded constructor. You can use any of the constructors to initialize the object of pen class. I use the following:

C#:

System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Black);

VB:

Dim pen As New System.Drawing.Pen(System.Drawing.Color.Red)

The second and third arguments are the object of point class. The point class also provides us four overloaded constructor, depending on your requirement you can use any of them. I use the following:

C#:

Point point1 = new Point(25,35);

Vb:

Dim point1 As New System.Drawing.Point(25,35)

 

Pass all these arguments in the DrawLine() function provided by the graphics class. Once you do this then you have to call the Dispose() method to epose your created line. The dispose() function takes no argument as a paameter. This function simply expose your graphics on the form. You have to call this function with the object of graphics and also with the object of pen class.

 

C#:

       pen.Dispose();

 

VB:

               pen.Dispose();

To demonstrate make a new window application and write the following code on form’s onpaint event:

C#:

protected override void OnPaint (PaintEventArgs e)

        {

            System.Drawing.Pen pen = new                      System.Drawing.Pen(System.Drawing.Color.Black);

            System.Drawing.Graphics obj;

            Point point1 = new Point(25,35);

            Point point2 = new Point(35,25);

            obj = this.CreateGraphics();

            obj.DrawLine(pen,point1,point2);

            pen.Dispose();

            obj.Dispose();

       }

 

VB:

Protected Overrides Sub OnPaint(ByVal As PaintEventArgs)
        
Dim pen As System.Drawing.Pen = New System.Drawing.Pen(System.Drawing.Color.Black)
        
Dim obj As System.Drawing.Graphics
        
Dim point1 As Point = New Point(2535)
        
Dim point2 As Point = New Point(3525)
        obj 
= Me.CreateGraphics
        obj.DrawLine(pen, point1, point2)
        pen.Dispose
        obj.Dispose
    
End Sub

Now write the following code on FORM LOAD event:

C#:

private void Form1_Load(object sender, EventArgs e)

        {

            this.Text = "DEVASP LINE DRAW APPLICATION";

           

        }

Vb:

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)

 

        Me.Text = "DEVASP LINE DRAW APPLICATION"

    End Sub

This simple article tells that how to draw a line using Graphics class in vb and C #.net.

   
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