Csharp/CSharp Tutorial/2D/Region

Create an irregular Region add a circle to the region

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Data; using System.Drawing; using System.Drawing.Drawing2D; using System.Text; using System.Windows.Forms; public class Form1 : Form {

   protected override void OnPaint(PaintEventArgs e) {
       Graphics g = e.Graphics;
       g.FillRectangle(Brushes.White, this.ClientRectangle);
       Region reg = new Region();
       reg.MakeEmpty();
       GraphicsPath gp = new GraphicsPath();
       gp.AddEllipse(10, 10, 50, 50);
       reg.Union(gp);
       gp.Reset();
       gp.AddLine(40, 40, 70, 10);
       gp.AddLine(70, 10, 100, 40);
       gp.CloseFigure();
       reg.Union(gp);
       reg.Union(new Rectangle(40, 50, 60, 60));
       g.SetClip(reg, CombineMode.Replace);
       g.FillRectangle(Brushes.Green, this.ClientRectangle);
       gp.Dispose();
       reg.Dispose();
   }
   public static void Main() {
       Application.Run(new Form1());
   }

}</source>

Create a Region object, cut a rectangular hole in it, and fill it

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Data; using System.Drawing; using System.Drawing.Drawing2D; using System.Text; using System.Windows.Forms; public class Form1 : Form {

   protected override void OnPaint(PaintEventArgs e) {
   Graphics g = e.Graphics;
   g.FillRectangle(Brushes.White, this.ClientRectangle);
   Region r = new Region(new Rectangle(30, 30, 30, 60));
   r.Exclude(new Rectangle(40, 40, 10, 10));
   g.FillRegion(Brushes.Orange, r);
   Console.WriteLine("This Region: ");
   Console.WriteLine(r.IsInfinite(g) ? " - is infinite" : " - is finite");
   Console.WriteLine(r.IsEmpty(g) ? " - is empty" : " - is non-empty");
   PointF pf = new PointF(35.0f, 30.0f);
   Console.WriteLine((r.IsVisible(pf) ? " - includes" : " - excludes") + " the point (35.0, 50.0)");
   Rectangle rect = new Rectangle(25, 65, 15, 15);
   g.DrawRectangle(Pens.Black, rect);
   Console.WriteLine((r.IsVisible(rect) ? " - is visible" : " - is invisible") + " in the rectangle shown");
   r.Dispose();
   }
   public static void Main() {
       Application.Run(new Form1());
   }

}</source>

Create a Region whose boundary is the above GraphicsPath

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Data; using System.Drawing; using System.Drawing.Drawing2D; using System.Text; using System.Windows.Forms; public class Form1 : Form {

   protected override void OnPaint(PaintEventArgs e) {
   Graphics g = e.Graphics;
   g.FillRectangle(Brushes.White, this.ClientRectangle);
   GraphicsPath gp = new GraphicsPath();
   gp.AddLine(10, 10, 10, 50);
   gp.AddLine(10, 50, 50, 50);
   gp.AddLine(50, 50, 50, 10);
   gp.StartFigure();
   gp.AddLine(60, 10, 60, 50);
   gp.AddLine(60, 50, 100, 50);
   gp.AddLine(100, 50, 100, 10);
   gp.CloseFigure();
   Rectangle r = new Rectangle(110, 10, 40, 40);
   gp.AddEllipse(r);
   Region reg = new Region(gp);
   g.FillRegion(Brushes.Green, reg);
   reg.Dispose();
   gp.Dispose();
   }
   public static void Main() {
       Application.Run(new Form1());
   }

}</source>

Region.IsVisible

<source lang="csharp">using System; using System.Drawing; using System.Collections; using System.ruponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Drawing2D; public class Form1 : System.Windows.Forms.Form {

   private System.Windows.Forms.Label label1;
   GraphicsPath gP;
   string mes = "Move to the big I!";
   FontFamily fF = new FontFamily("Times new roman");
   public Form1() {
       this.label1 = new System.Windows.Forms.Label();
       this.SuspendLayout();
       this.label1.Location = new System.Drawing.Point(88, 16);
       this.label1.Size = new System.Drawing.Size(160, 23);
       this.label1.Text = "label1";
       this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
       this.ClientSize = new System.Drawing.Size(292, 109);
       this.Controls.AddRange(new System.Windows.Forms.Control[] { this.label1 });
       this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.Form1_MouseMove);
       this.ResumeLayout(false);
       Graphics g = this.CreateGraphics();
       label1.Text = mes;
       string s = "I";
       int fSt = (int)FontStyle.Regular;
       Point xy = new Point(50, 10);
       StringFormat sFr = StringFormat.GenericDefault;
       gP = new GraphicsPath();
       gP.AddString(s, fF, fSt, 50, xy, sFr);
   }
   [STAThread]
   static void Main() {
       Application.Run(new Form1());
   }
   protected override void OnPaint(System.Windows.Forms.PaintEventArgs e) {
       Graphics g = this.CreateGraphics();
       g.DrawPath(Pens.Black, gP);  // draw the path to the surface
       g.Dispose();
   }
   private void Form1_MouseMove(object sender, MouseEventArgs e) {
       Region reg = new Region(gP);
       if (reg.IsVisible(new Point(e.X, e.Y)))
           mes = "in";
       else
           mes = "Move to the big I!";
   }

}</source>