【C#】多边形面积
Vector2類見前文
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms;namespace 多邊形面積 {public partial class Form1 : Form{public Form1(){InitializeComponent();}int clickCount = 0;Point[] d = new Point[100];List<PointF> PointList = new List<PointF>();private void Form1_MouseDown(object sender, MouseEventArgs e){Graphics g = this.CreateGraphics();Pen pen = new Pen(Color.Blue, 2);Brush brush = new SolidBrush(Color.Blue);g.DrawEllipse(pen, e.X, e.Y, 7, 7);g.FillEllipse(brush, e.X, e.Y, 7, 7);d[clickCount] = e.Location;if (clickCount >= 1){g.DrawLine(pen, d[clickCount], d[clickCount - 1]);PointF pPoint = new PointF(d[clickCount - 1].X, d[clickCount - 1].Y);PointList.Add(pPoint);}clickCount++;}public static float CalculateArea(List<PointF> vectorPoints){int iCycle, iCount;iCycle = 0;iCount = vectorPoints.Count;float iArea = 0;for (iCycle = 0; iCycle < iCount; iCycle++){iArea = iArea + (vectorPoints[iCycle].X * vectorPoints[(iCycle + 1) % iCount].Y - vectorPoints[(iCycle + 1) % iCount].X * vectorPoints[iCycle].Y);}float area = (float)Math.Abs(0.5 * iArea);return area;}private void button1_Click(object sender, EventArgs e){Graphics g = this.CreateGraphics();Pen pen = new Pen(Color.Blue, 2);g.DrawLine(pen, PointList[PointList.Count - 1], PointList[0]); //?-1就連錯點了,不-1又有溢出錯誤,咋辦捏float S = CalculateArea(PointList);MessageBox.Show("多邊形面積為:" + S);}} }(最后連線時有錯誤)
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