Merge pull request #646 from nuhash/DrawCircle

Implemented additional drawing function as per issue #603

Author: jp2masa

Demos/Cosmos Graphic Subsytem/Kernel.cs

@@ -48,6 +48,15 @@ protected override void Run()
                 pen.Color = Color.PaleVioletRed;
                 canvas.DrawRectangle(pen, 350, 350, 80, 60);
 
+                pen.Color = Color.Chartreuse;
+                canvas.DrawCircle(pen, 69, 69, 10);
+
+                pen.Color = Color.LightSalmon;
+                canvas.DrawEllipse(pen, 400, 300, 100, 150);
+
+                pen.Color = Color.MediumPurple;
+                canvas.DrawPolygon(pen, new Point(200, 250), new Point(250, 300), new Point(220, 350), new Point(210, 275));
+
                 /*
                  * It will be really beautiful to do here:
                  * canvas.DrawString(pen, "Please press any key to continue the Demo...");

Tests/GraphicTest/Kernel.cs

@@ -54,6 +54,15 @@ protected override void Run()
                 pen.Color = Color.PaleVioletRed;
                 canvas.DrawRectangle(pen, 350, 350, 80, 60);
 
+                pen.Color = Color.Chartreuse;
+                canvas.DrawCircle(pen, 69, 69, 10);
+
+                pen.Color = Color.DimGray;
+                canvas.DrawEllipse(pen, 100, 69, 10, 50);
+
+                pen.Color = Color.MediumPurple;
+                canvas.DrawPolygon(pen, new Point(200, 250), new Point(250, 300), new Point(220, 350), new Point(210, 275));
+
                 Console.ReadKey();
 
                 /* Let's try to change mode...*/

source/Cosmos.System/Graphics/Canvas.cs

@@ -5,6 +5,8 @@
 using System.Text;
 using System.Threading.Tasks;
 using System.Drawing;
+using System.Collections;
+using System.Collections.ObjectModel;
 
 namespace Cosmos.System.Graphics
 {
@@ -84,6 +86,8 @@ public virtual void Clear(Color color)
             }
         }
 
+        
+
         public abstract void DrawPoint(Pen pen, int x, int y);
 
         public abstract void DrawPoint(Pen pen, float x, float y);
@@ -185,11 +189,100 @@ public void DrawLine(Pen pen, int x1, int y1, int x2, int y2)
             DrawDiagonalLine(pen, dx, dy, x1, y1);
         }
 
+        public void DrawLine(Pen pen, Point p1, Point p2)
+        {
+            DrawLine(pen, p1.X, p1.Y, p2.X, p2.Y);
+        }
+
         public void DrawLine(Pen pen, float x1, float y1, float x2, float y2)
         {
             throw new NotImplementedException();
         }
 
+        //https://en.wikipedia.org/wiki/Midpoint_circle_algorithm
+        public virtual void DrawCircle(Pen pen, int x_center, int y_center, int radius)
+        {
+            if (pen == null)
+                throw new ArgumentNullException(nameof(pen));
+            ThrowIfCoordNotValid(x_center + radius, y_center);
+            ThrowIfCoordNotValid(x_center - radius, y_center);
+            ThrowIfCoordNotValid(x_center, y_center + radius);
+            ThrowIfCoordNotValid(x_center, y_center - radius);
+            int x = radius;
+            int y = 0;
+            int e = 0;
+
+            while(x>=y)
+            {
+                DrawPoint(pen, x_center + x, y_center + y);
+                DrawPoint(pen, x_center + y, y_center + x);
+                DrawPoint(pen, x_center - y, y_center + x);
+                DrawPoint(pen, x_center - x, y_center + y);
+                DrawPoint(pen, x_center - x, y_center - y);
+                DrawPoint(pen, x_center - y, y_center - x);
+                DrawPoint(pen, x_center + y, y_center - x);
+                DrawPoint(pen, x_center + x, y_center - y);
+
+                y++;
+                if(e<=0)
+                {
+                    e += 2 * y + 1;
+                }
+                if(e>0)
+                {
+                    x--;
+                    e -= 2 * x + 1;
+                }
+            }
+        }
+
+        //http://members.chello.at/~easyfilter/bresenham.html
+        public virtual void DrawEllipse(Pen pen, int x_center, int y_center, int x_radius, int y_radius)
+        {
+            if (pen == null)
+                throw new ArgumentNullException(nameof(pen));
+            ThrowIfCoordNotValid(x_center + x_radius, y_center);
+            ThrowIfCoordNotValid(x_center - x_radius, y_center);
+            ThrowIfCoordNotValid(x_center, y_center + y_radius);
+            ThrowIfCoordNotValid(x_center, y_center - y_radius);
+            int a = 2 * x_radius;
+            int b = 2 * y_radius;
+            int b1 = b & 1;
+            int dx = 4 * (1 - a) * b * b;
+            int dy = 4 * (b1 + 1) * a * a;
+            int err = dx + dy + b1 * a * a;
+            int e2;
+            int y = 0;
+            int x = x_radius;
+            a *= 8 * a;
+            b1 = 8 * b * b;
+
+            while (x>=0)
+            {
+                DrawPoint(pen, x_center + x, y_center + y);
+                DrawPoint(pen, x_center - x, y_center + y);
+                DrawPoint(pen, x_center - x, y_center - y);
+                DrawPoint(pen, x_center + x, y_center - y);
+                e2 = 2 * err;
+                if (e2 <= dy) { y++; err += dy += a; }
+                if (e2 >= dx || 2 * err > dy) { x--; err += dx += b1; }
+            }
+        }
+
+        public virtual void DrawPolygon(Pen pen, params Point[] points)
+        {
+            if (points.Length < 3)
+                throw new ArgumentException("A polygon requires more than 3 points.");
+            if (pen == null)
+                throw new ArgumentNullException(nameof(pen));
+
+            for (int i = 0; i < points.Length - 1; i++)
+            {
+                DrawLine(pen, points[i], points[i + 1]);
+            }
+            DrawLine(pen, points[0], points[points.Length - 1]);
+        }
+
         public void DrawRectangle(Pen pen, int x, int y, int width, int height)
         {
             /*
@@ -303,4 +396,25 @@ protected void ThrowIfCoordNotValid(int x, int y)
             }
         }
     }
+
+    public class Point
+    {
+        public Point(int x, int y)
+        {
+            this.X = x;
+            this.Y = y;
+        }
+        int x;
+        public int X
+        {
+            get { return x; }
+            set { x = value; }
+        }
+        int y;
+        public int Y
+        {
+            get { return y; }
+            set { y = value; }
+        }
+    }
 }