C# | Graphics.DrawLine() Method | Set – 1

Last Updated : 17 Apr, 2019

Graphics.DrawLine() Method is used to draw a line connecting the two points specified by the coordinate pairs. There are 4 methods in the overload list of this method as follows:

DrawLine(Pen, PointF, PointF) Method
DrawLine(Pen, Int32, Int32, Int32, Int32) Method
DrawLine(Pen, Single, Single, Single, Single) Method

DrawLine(Pen, Point, Point) Method

Here, we will discuss the first two methods.

DrawLine(Pen, PointF, PointF) Method

This method is used to draw line form a specified set of points to a specified set of points. It needs a PointF variable which is set of (x, y) points.

Syntax:

public void DrawLine (System.Drawing.Pen pen, System.Drawing.PointF pt1, System.Drawing.PointF pt2);

Parameters:

pen: Pen determines the color, width, and style of the line.
pt1: Defines the (x, y) coordinates as a PointF variable of the initial point.
pt2: Defines the (x, y) coordinates as a PointF variable of the final point.

Exception: This method will give ArgumentNullexception if the pen is null.

Example:

// C# program to demonstrate the 
// DrawLine(Pen, PointF, PointF) Method
using System;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;
  
namespace GFG {
  
class PrintableForm : Form {
  
    public static void Main()
    {
        Application.Run(new PrintableForm());
    }
  
    public PrintableForm()
    {
        ResizeRedraw = true;
    }
    protected override void OnPaint(PaintEventArgs pea)
    {
        // Defines pen
        Pen pen = new Pen(ForeColor);
  
        // Defines the both points to connect
        // pt1 is (30.0, 30.0) which represents (x1, y1)
        PointF pt1 = new PointF(30.0F, 30.0F);
  
        // pt2 is (200.0, 300.0) which represents (x2, y2)
        PointF pt2 = new PointF(200.0F, 300.0F);
  
        // Draws the line
        pea.Graphics.DrawLine(pen, pt1, pt2);
    }
}
}

Output:

DrawLine(Pen, Int32, Int32, Int32, Int32) Method

This method is used to draw line form a specified set of coordinates given in form x1, y1, x2, y2 all discrete.

Syntax:

public void DrawLine (System.Drawing.Pen pen, int x1, int y1, int x2, int y2);

Parameters:

pen: Pen determines the color, width, and style of the line.
x1: The abscissa of first point.
y1: The ordinate of first point.
x2: The abscissa of second point.
y2: The ordinate of second point.

Exception: This method will give ArgumentNullexception if the pen is null.

Example 1:

// C# program to draw a cross using the
// DrawLine(Pen, Int32, Int32, Int32,
// Int32) Method
using System;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;
  
namespace GFG {
  
class PrintableForm : Form {
  
    public static void Main()
    {
        Application.Run(new PrintableForm());
    }
  
    public PrintableForm()
    {
        ResizeRedraw = true;
    }
  
    protected override void OnPaint(PaintEventArgs pea)
    {
        // Defines the pen
        Pen pen = new Pen(ForeColor);
  
        // To draw a cross we need to make 2 
        // diagonals from top-left to the 
        // bottom-right and top-right to the 
        // bottom-left to calculate these 
        // coordinates we would take help of 
        // our screen size top-left = (0, 0)
        // bottom-right = (ClientSize.Width - 1,
        // ClientSize.Height - 1)
        // top-right = (ClientSize.Width - 1, 0)
        // bottom-left = (0, ClientSize.Height - 1)
        pea.Graphics.DrawLine(pen, 0, 0, ClientSize.Width - 1,
                                       ClientSize.Height - 1);
  
        pea.Graphics.DrawLine(pen, ClientSize.Width - 1, 0, 0,
                                       ClientSize.Height - 1);
    }
}
}

Output:

Example 2:

// C# program to Create a 8x8 square board
// using // DrawLine(Pen, Int32, Int32, Int32,
// Int32) Method
using System;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;
  
namespace GFG {
  
class PrintableForm : Form {
  
    public static void Main()
    {
        Application.Run(new PrintableForm());
    }
  
    public PrintableForm()
    {
        ResizeRedraw = true;
    }
  
    protected override void OnPaint(PaintEventArgs pea)
    {
        // Define Pen
        Pen pen = new Pen(ForeColor);
  
        // loop for all 7 horizontal lines to draw
        for (int i = 0; i < 7; i++) 
        {
            // Taking Block size to be 30x30
            // So width and height will be 30*8=240
            pea.Graphics.DrawLine(pen, i * 30, 0, i * 30, 240);
        }
  
        // loop for all 7 horizontal lines to draw
        for (int i = 0; i < 7; i++) 
        {
            pea.Graphics.DrawLine(pen, 0, i * 30,
                                    240, i * 30);
        }
    }
}
}