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

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);
        }
    }
}
}

Output: