### C#WPF 如何繪制幾何圖形 圖示教程 繪制sin曲線 正弦 繪制2D坐標系 有圖有代碼

C#WPF 如何繪制幾何圖形？ 怎么繪制坐標系？繪制sin曲線（正弦曲線）？

MainWindow.xaml 中代碼

```<Window x:Class="WPFDrawingTraning.MainWindow"
xmlns="<a target=_blank href="http://schemas.microsoft.com/winfx/2006/xaml/presentation">http://schemas.microsoft.com/winfx/2006/xaml/presentation</a>"
xmlns:x="<a target=_blank href="http://schemas.microsoft.com/winfx/2006/xaml">http://schemas.microsoft.com/winfx/2006/xaml</a>"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Canvas Name="mainPanel" HorizontalAlignment="Left" Height="320" VerticalAlignment="Top" Width="517"/>
</Grid>
</Window>

```

MainWindow.xaml.cs中代碼

```using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace WPFDrawingTraning
{
/// <summary>
/// MainWindow.xaml 的交互邏輯
/// </summary>
public partial class MainWindow : System.Windows.Window
{
//Canvas mainPanel = new Canvas();
public MainWindow()
{
InitializeComponent();

Drawsin();//繪制2D坐標系和sin曲線

Drawpentagon();

}
/// <summary>
/// 繪制一組線段
/// </summary>
protected void Drawing()
{
PathFigure myPathFigure = new PathFigure();
myPathFigure.StartPoint = new Point(10, 50);

LineSegment myLineSegment = new LineSegment();
myLineSegment.Point = new Point(200, 70);

PathSegmentCollection myPathSegmentCollection = new PathSegmentCollection();

myPathFigure.Segments = myPathSegmentCollection;

PathFigureCollection myPathFigureCollection = new PathFigureCollection();

PathGeometry myPathGeometry = new PathGeometry();
myPathGeometry.Figures = myPathFigureCollection;

Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
myPath.Data = myPathGeometry;

// Add path shape to the UI.
StackPanel mainPanel = new StackPanel();
this.Content = mainPanel;

}
/// <summary>
/// 繪制線段
/// </summary>
protected void DrawingLine(Point startPt,Point endPt)
{
LineGeometry myLineGeometry = new LineGeometry();
myLineGeometry.StartPoint = startPt;
myLineGeometry.EndPoint = endPt;

Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
myPath.Data = myLineGeometry;

}
/// <summary>
/// 繪制星狀線
/// </summary>
protected void DrawingAstroid(Point center,double r)
{

double h1 = r * Math.Sin(18 * Math.PI / 180);
double h2 = r * Math.Cos(18*Math.PI/180);
double h3 = r * Math.Sin(36 * Math.PI / 180);
double h4 = r * Math.Cos(36 * Math.PI / 180); ;
Point p1 = new Point(r, 0);
Point p2 = new Point(r - h2, r - h1);
Point p3 = new Point(r - h3, r + h4);
Point p4 = new Point(r + h3, p3.Y);
Point p5 = new Point(r + h2, p2.Y);
Point[] values = new Point[] { p1, p2, p3, p4, p5 };
PathFigureCollection myPathFigureCollection = new PathFigureCollection();
PathGeometry myPathGeometry = new PathGeometry();

for (int i = 0; i < values.Length; i++)
{
//DrawingLine(center, values[i]);
PathFigure myPathFigure = new PathFigure();
myPathFigure.StartPoint = center;

LineSegment myLineSegment = new LineSegment();
myLineSegment.Point = values[i];

PathSegmentCollection myPathSegmentCollection = new PathSegmentCollection();

myPathFigure.Segments = myPathSegmentCollection;

}
myPathGeometry.Figures = myPathFigureCollection;
Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
myPath.Data = myPathGeometry;

}

/// <summary>
/// 繪制坐標系和sin曲線
/// </summary>
private void Drawpentagon()
{
Point center = new Point(50, 50);
double r = 50;
DrawingAstroid(center, r);

double h1 = r * Math.Sin(18 * Math.PI / 180);
double h2 = r * Math.Cos(18 * Math.PI / 180);
double h3 = r * Math.Sin(36 * Math.PI / 180);
double h4 = r * Math.Cos(36 * Math.PI / 180); ;
Point p1 = new Point(r, 0);
Point p2 = new Point(r - h2, r - h1);
Point p3 = new Point(r - h3, r + h4);
Point p4 = new Point(r + h3, p3.Y);
Point p5 = new Point(r + h2, p2.Y);
Point[] values = new Point[] { p1, p3, p5, p2, p4 };
// Create a path to draw a geometry with.
Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
StreamGeometry theGeometry = BuildRegularPolygon(values, true, false);
// Create a StreamGeometry to use to specify myPath.
theGeometry.FillRule = FillRule.EvenOdd;

// Freeze the geometry (make it unmodifiable)
theGeometry.Freeze();

// Use the StreamGeometry returned by the BuildRegularPolygon to
// specify the shape of the path.
myPath.Data = theGeometry;

// Add path shape to the UI.

}

/// <summary>
/// 繪制連續的線段
/// </summary>
/// <param name="values"></param>
/// <returns></returns>
private StreamGeometry BuildRegularPolygon(Point[] values, bool isClosed,bool isfilled)
{
// c is the center, r is the radius,
// numSides the number of sides, offsetDegree the offset in Degrees.
// Do not add the last point.

StreamGeometry geometry = new StreamGeometry();

using (StreamGeometryContext ctx = geometry.Open())
{
ctx.BeginFigure(values[0], isfilled /* is filled */, isClosed /* is closed */);

for (int i = 1; i < values.Length; i++)
{
ctx.LineTo(values[i], true /* is stroked */, false /* is smooth join */);
}
}

return geometry;

}

/// <summary>
/// 繪制五角星
/// </summary>
private void Drawsin()
{
Point point = new Point(this.mainPanel.Width, this.mainPanel.Height);
Point xypoint = new Point(point.X / 2, point.Y / 2);//新坐標原點

//x軸坐標起點
Point xstartpoint = new Point(0, point.Y / 2);
//x軸坐標終點
Point xendpoint = new Point(point.X, point.Y / 2);

//y軸坐標起點
Point ystartpoint = new Point(point.X / 2, point.Y);
//y軸坐標終點
Point yendpoint = new Point(point.X / 2, 0);

Line xline = new Line();
xline.Stroke = System.Windows.Media.Brushes.LightSteelBlue;

xline.X1 = 0;
xline.Y1 = this.mainPanel.Height / 2;

xline.X2 = this.mainPanel.Width;
xline.Y2 = this.mainPanel.Height / 2;

Line yline = new Line();
yline.Stroke = System.Windows.Media.Brushes.LightSteelBlue;

yline.X1 = this.mainPanel.Width / 2;
yline.Y1 = this.mainPanel.Height;

yline.X2 = this.mainPanel.Width / 2;
yline.Y2 = 0;

Point[] points=new Point[1000];

//繪制sin曲線,從原點（0,0）開始
Point zpoint = new Point(0, 0);
zpoint = XYTransf(zpoint, xypoint);
points[0] = zpoint;//sin曲線的起點

for (int i = 1; i < 1000; i++)
{
//計算sin（x，y）
point.X =10 * i;//x
point.Y =10 * Math.Sin(i);//y

//坐標轉換
point = XYTransf(point, xypoint);
points[i] = point;

}

Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
StreamGeometry theGeometry = BuildRegularPolygon(points, true, false);
// Create a StreamGeometry to use to specify myPath.
theGeometry.FillRule = FillRule.EvenOdd;

// Freeze the geometry (make it unmodifiable)
theGeometry.Freeze();

// Use the StreamGeometry returned by the BuildRegularPolygon to
// specify the shape of the path.
myPath.Data = theGeometry;

// Add path shape to the UI.

}

//構建的XY坐標系中的坐標轉換為界面坐標系
public Point XYTransf(Point point, Point xypoint)```
```        {
point.X += xypoint.X;
point.Y = xypoint.Y - point.Y;

return point;//顯示屏幕坐標系的位置
}
}
}
```

private void Drawsin()  函數中完成：坐標系繪制，sin曲線繪制；

point是繪圖坐標系中的點，xypoint（maincanvas.Width/2,maincanvas.Height/2）是繪圖屏幕坐標的幾何中心點（ 圖 坐標點轉換，中x軸和y軸原點）的坐標。

public Point XYTransf(Point point, Point xypoint）函數返回值是在屏幕坐標繪制點的坐標。

//轉換為界面坐標系
public Point XYTransf(Point point, Point xypoint）

```        {
point.X += xypoint.X;
point.Y = xypoint.Y - point.Y;

return point;//顯示屏幕坐標系的位置
}```

1.mainPanel  是一個Canvas面板，我們在該面板繪制圖形。

2.繪制坐標系，以mainPanel 的圖形中心為坐標原點；

圖 坐標點轉換

3.計算sin（x，y）並轉換為屏幕坐標點，取1000個坐標點，並存在points數組中

```            for (int i = 1; i < 1000; i++)
{
//計算sin（x，y）
point.X =10 * i;//sin x
point.Y =10 * Math.Sin(i);//sin y

//坐標轉換
point = XYTransf(point, xypoint);
points[i] = point;

}```

4.連接1000個sin（x，y）的屏幕坐標點，並顯示在Canvas中

StreamGeometry theGeometry = BuildRegularPolygon(points, true, false);   通過該函數連接points中所有的點；

```            Path myPath = new Path();
myPath.Stroke = Brushes.Black;
myPath.StrokeThickness = 1;
StreamGeometry theGeometry = BuildRegularPolygon(points, true, false);
// Create a StreamGeometry to use to specify myPath.
theGeometry.FillRule = FillRule.EvenOdd;

// Freeze the geometry (make it unmodifiable)
theGeometry.Freeze();

// Use the StreamGeometry returned by the BuildRegularPolygon to
// specify the shape of the path.
myPath.Data = theGeometry;

// Add path shape to the UI.

5.執行顯示效果