Draw an arrow on a Picturebox in C #

Question

I want to be able to draw a straight arrow from one place of a mouse click to another, as if you were doing it in PowerPoint. It should also be able to draw on the PictureBox, please help,

thank

Answer 1

Here is the basic code for drawing lines in a frame from the mouse to the current location. You just need to draw some more lines or a triangle for the arrowhead.

public partial class Form1 : Form
{
    private bool isMoving = false;
    private Point mouseDownPosition = Point.Empty;
    private Point mouseMovePosition = Point.Empty;
    private List<Tuple<Point, Point>> lines = new List<Tuple<Point, Point>>();
    public Form1()
    {
        InitializeComponent();

        // 
        // pictureBox1
        // 
        this.pictureBox1.Location = new System.Drawing.Point(0, 0);
        this.pictureBox1.Name = "pictureBox1";
        this.pictureBox1.Size = new System.Drawing.Size(231, 235);
        this.pictureBox1.TabIndex = 0;
        this.pictureBox1.TabStop = false;
        this.pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);
        this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
        this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
        this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);
        this.Controls.Add(this.pictureBox1);
    }

    private void pictureBox1_Paint(object sender, PaintEventArgs e)
    {
        var g = e.Graphics;
        if (isMoving)
        {
            g.Clear(pictureBox1.BackColor);
            g.DrawLine(Pens.Black, mouseDownPosition, mouseMovePosition);
            foreach (var line in lines)
            {
                g.DrawLine(Pens.Black, line.Item1, line.Item2);
            }
        }
    }

    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        isMoving = true;
        mouseDownPosition = e.Location;
    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (isMoving)
        {
            mouseMovePosition = e.Location;
            pictureBox1.Invalidate();
        }
    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        if (isMoving)
        {
            lines.Add(Tuple.Create(mouseDownPosition, mouseMovePosition));
        }
        isMoving = false;
    }
}

Answer 2

It’s easy to draw arrows just as you drew the lines on PictureBoxin the previous question .

, , StartCap EndCap Pen, , . StartCap , , Pen , EndCap .

LineCap, :

Flat          Specifies a flat line cap.
Square        Specifies a square line cap.
Round         Specifies a round line cap.
Triangle      Specifies a triangular line cap.
NoAnchor      Specifies no anchor.
SquareAnchor  Specifies a square anchor line cap.
RoundAnchor   Specifies a round anchor cap.
DiamondAnchor Specifies a diamond anchor cap.
ArrowAnchor   Specifies an arrow-shaped anchor cap.
Custom        Specifies a custom line cap.
AnchorMask    Specifies a mask used to check whether a line cap is an anchor cap.

, ArrowAnchor : ArrowAnchor LineCap ( , , ).

, , 4:

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
 //Create a new pen to draw the arrow with
 using (Pen p = new Pen(Brushes.Green, 4f))
 {
  //Specify the EndCap, because we're drawing a right-facing arrow
  p.EndCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;

  //Draw the arrow
  e.Graphics.DrawLine(p, 0, 0, 30, 45);
 }
}

Answer 3

citing Albin Sunnanbo's answer , which was great stuff

If you want to draw an arrow , just replace

 g.DrawLine(Pens.Black, mouseDownPosition, mouseMovePosition); 

to

Pen p = new Pen(Color.Black,3);
p.StartCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;
g.DrawLine(p, mouseDownPosition, mouseMovePosition);
p.Dispose();