# Draw, Plot 2d Line In C# (csharp) - Bresenham's Line Algorithm

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```based on wikipedia
```
public interface ISetPixel
{
void SetPixel(Point point);
}
public partial class Algorithms2D
{
public delegate void SetPixel(Point point);
public static void Line(Point p0,Point p1,G plot)
where G:ISetPixel
{
int x0=p0.X;
int y0=p0.Y;
int x1=p1.X;
int y1=p1.Y;
bool steep=abs(y1-y0)>abs(x1-x0);
if (steep)
{
swap(ref x0,ref y0);
swap(ref x1,ref y1);
}
if (x0>x1)
{
swap(ref x0,ref x1);
swap(ref y0,ref y1);
}
int deltax=x1-x0;
int deltay=abs(y1-y0);
int error=-deltax/2;
int ystep;
int y=y0;
if (y00)
{
y=y+ystep;
error=error-deltax;
}
}
}
struct CSetPixel:ISetPixel
{
public CSetPixel(SetPixel setPixel)
{
this.setPixel=setPixel;
}
SetPixel setPixel;
#region ISetPixel Members
public void SetPixel(Point point)
{
setPixel(point);
}
#endregion
}
public static void Line(Point p0,Point p1,SetPixel plot)
{
Line(p0,p1,new CSetPixel(plot));
}
private static int abs(int p)
{
return Math.Abs(p);
}
private static void swap(ref T x0,ref T y0)
{
T z=x0;
x0=y0;
y0=z;
}
}
```

unit tests (c# 3.0):

```
[TestFixture]
public class Line
{
[Test]
public void LineDiagonal()
{
List l = new List();
Assert.AreEqual(3, l.Count);
Assert.AreEqual(new Point(0, 0), l[0]);
Assert.AreEqual(new Point(1, 1), l[1]);
Assert.AreEqual(new Point(2, 2), l[2]);
}
[Test]
public void Line45()
{
List l = new List();
Algorithms2D.Line(new Point(0, 0),new Point(6, 3), z => l.Add(z));
Assert.AreEqual(6, l.Count);
Assert.AreEqual(new Point(0, 0), l[0]);
Assert.AreEqual(new Point(1, 0), l[1]);
Assert.AreEqual(new Point(2, 1), l[2]);
Assert.AreEqual(new Point(3, 1), l[3]);
Assert.AreEqual(new Point(4, 2), l[4]);
Assert.AreEqual(new Point(5, 2), l[5]);
}
}
``````
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