Draw an Arrow on a Picturebox in C# [closed]
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Improve this questionI want to be able to draw a straight arrow from one mouse click location to开发者_JS百科 another, as if you were doing it in PowerPoint. It needs to be able to draw on a PictureBox as well.
Here is some basic code to draw lines in a picturebox from mouse down to current location.
You just need to draw some more lines or a triangle for the arrow head.
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;
}
}
It's easy to draw arrows in the same way that you worked out how to draw lines on a PictureBox
in a previous question.
All you have to do is specify a StartCap
or EndCap
for the Pen
object you are already using to draw lines. Intuitively, the StartCap
property allows you to specify a cap style that is used at the beginning of any lines you draw with the Pen
object, while the EndCap
property allows you to specify a cap style for the end of the lines.
Several different LineCap
styles are available, including:
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.
You will probably find the ArrowAnchor
style most useful in this case: just specify an ArrowAnchor
as the LineCap
style for either the start or end of the line (depending on the direction in which you want the arrow to point).
The following code will draw a green, right-facing arrow with a line thickness of 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);
}
}
with reference to Albin Sunnanbo answer that was great stuff
If you want to draw 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();
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