上一篇【学习笔记】Windows GDI绘图(五)图形路径GraphicsPath详解(上)介绍了GraphicsPath类的构造函数、属性和方法AddArc添加椭圆弧、AddBezier添加贝赛尔曲线、AddClosedCurve添加封闭基数样条曲线、AddCurve添加开放基数样条曲线、基数样条如何转Bezier、AddEllipse添加椭圆、AddLine添加线段。

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GraphicsPath方法

AddLines添加线段

原型：

public void AddLines (params System.Drawing.Point[] points);
public void AddLines (params System.Drawing.PointF[] points);

添加一系列的线段到GraphicsPath中。

// 定义三角形的顶点
Point[] points =
         {
            new Point(150,150),
            new Point(300,300),
            new Point(0,300),
            new Point(150,150)
          };

using (var myPath = new GraphicsPath())
{
    myPath.AddLines(points);

    e.Graphics.DrawPath(penRed, myPath);
}

通过点集绘制线段

AddPath附加路径

原型：

public void AddPath (System.Drawing.Drawing2D.GraphicsPath addingPath, bool connect);

connect，当前路径与附加的路径是否相连
将指定的GraphicsPath附加到当前Path中

Point[] myArray =
         {
     new Point(120,120),
     new Point(240,240),
     new Point(0,240),
     new Point(120,120)
 };
GraphicsPath myPath = new GraphicsPath();
myPath.AddLines(myArray);

Point[] myArray2 =
         {
     new Point(120,100),
     new Point(20,20),
     new Point(220,20),
     new Point(120,100)
 };
GraphicsPath myPath2 = new GraphicsPath();
myPath2.AddLines(myArray2);

// Add the second path to the first path.
myPath.AddPath(myPath2, false);//各自独立

// Draw the combined path to the screen.
e.Graphics.DrawPath(penRed, myPath);

myPath.Reset();
myPath.AddLines(myArray);
myPath.AddPath(myPath2, true);//相连

myPath.Transform(new Matrix(1, 0, 0, 1, 400, 0));
e.Graphics.DrawPath(penLightGreen, myPath);

AddPie添加饼形

原型：

public void AddPie (System.Drawing.Rectangle rect, float startAngle, float sweepAngle);
public void AddPie (int x, int y, int width, int height, float startAngle, float sweepAngle);
public void AddPie (float x, float y, float width, float height, float startAngle, float sweepAngle);

通过一个矩形、起始角度和扫描角度来角度一个饼形，与椭圆参数类似。

var rect = new Rectangle(100, 100, 200, 100);
using (var path = new GraphicsPath())
{
    //添加饼形 30°至150°
    path.AddPie(rect, 30, 120);
    e.Graphics.DrawPath(penRed, path);

    path.Reset();
    //150°至270°
    path.AddPie(rect, 30 + 120, 120);
    e.Graphics.DrawPath(penLightGreen, path);

    path.Reset();
    //30°到 270°（逆时针）
    path.AddPie(rect, 30, -120);
    e.Graphics.DrawPath(Pens.Chocolate, path);
}           
  

sweepAngle，正数，顺时针；负数，逆时针

AddPolygon添加多边形

原型：

public void AddPolygon (System.Drawing.Point[] points);
public void AddPolygon (System.Drawing.PointF[] points);

定义点集，形成多边形

// 多边形顶点
Point[] myArray =
         {
     new Point(230, 200),
     new Point(400, 100),
     new Point(570, 200),
     new Point(500, 400),
     new Point(300, 400)
 };

using (var myPath = new GraphicsPath())
{
    //添加多边形
    myPath.AddPolygon(myArray);
    e.Graphics.DrawPath(penRed, myPath);
}

AddRectangle和AddRectangles 添加矩形

原型：

public void AddRectangle (System.Drawing.RectangleF rect);
public void AddRectangle (System.Drawing.Rectangle rect);
public void AddRectangles (System.Drawing.Rectangle[] rects);
public void AddRectangles (params System.Drawing.RectangleF[] rects);

定义矩形和矩形集，添加到路径中。

var rect = new Rectangle(30, 50, 100, 80);

var rects = new RectangleF[]
{
    new RectangleF(150,50,80,60),
    new RectangleF(200,80,100,80)
};

using (var myPath = new GraphicsPath())
{                
    myPath.AddRectangle(rect);
    myPath.AddRectangles(rects);
    e.Graphics.DrawPath(penRed, myPath);
}

AddString添加字符串

原型：

public void AddString (string s, System.Drawing.FontFamily family, int style, float emSize, System.Drawing.Point origin, System.Drawing.StringFormat? format);
public void AddString (string s, System.Drawing.FontFamily family, int style, float emSize, System.Drawing.PointF origin, System.Drawing.StringFormat? format);
public void AddString (string s, System.Drawing.FontFamily family, int style, float emSize, System.Drawing.Rectangle layoutRect, System.Drawing.StringFormat? format);
public void AddString (string s, System.Drawing.FontFamily family, int style, float emSize, System.Drawing.RectangleF layoutRect, System.Drawing.StringFormat? format);

参数	说明
s	待添加的文本
family	FontFamily字体名称
style	文本样式,Bold-1,Italic-2,Regular-0,Strikeout-8,Underline-4
emSize	文本高度，单位：像素
origin	文本起始点，默认是左对齐时，是左上角
format	指定文本格式信息，例如行距和对齐方式

这里先随便给个示例吧，估计关于绘制文本，可以另起一篇。

// Create a GraphicsPath object.
GraphicsPath myPath = new GraphicsPath();

// Set up all the string parameters.
string stringText = "我在学习GDI+";
FontFamily family = new FontFamily("Arial");
int fontStyle = (int)FontStyle.Italic;
int emSize = 38;//文本高度，像素
Point origin = new Point(200, 100);//文本开始绘制的左上角点

StringFormat format = new StringFormat(StringFormatFlags.NoWrap);
format.Alignment = StringAlignment.Center;//水平居中
format.LineAlignment = StringAlignment.Center; // 垂直居中

// Add the string to the path.
myPath.AddString(stringText,
    family,
    fontStyle,
    emSize,
    origin,
    format);

e.Graphics.FillPath(Brushes.Green, myPath);

//文本定位点
e.Graphics.FillEllipse(Brushes.Red, origin.X - 3, origin.Y - 3, 6, 6);

SetMarkers设置标记

原型：

public void SetMarkers ();

使用 SetMarkers 方法在 GraphicsPath 中的当前位置创建标记。使用 NextMarker 方法迭代路径中的现有标记。
标记用于分隔子路径组。两个标记之间可以包含一个或多个子路径。

[System.ComponentModel.Description("GraphicsPath的SetMarkers/ClearMarkers方法")]
public void Demo06_07(PaintEventArgs e)
{
    // Create a path and set two markers.
    GraphicsPath myPath = new GraphicsPath();
    myPath.AddLine(new Point(0, 0), new Point(50, 50));
    myPath.SetMarkers();
    Rectangle rect = new Rectangle(50, 50, 50, 50);
    myPath.AddRectangle(rect);
    myPath.SetMarkers();
    myPath.AddEllipse(100, 100, 100, 50);

    // Draw the path to screen.
    e.Graphics.DrawPath(new Pen(Color.Black, 2), myPath);

    var pathIterator =new GraphicsPathIterator(myPath);
    pathIterator.Rewind();

    var potins = myPath.PathPoints;
    var types = myPath.PathTypes;

    var height = 20;
    var markerIndex = 0;
    int startIndex;
    int endIndex;
    while(true)
    {
        var resultCount = pathIterator.NextMarker(out startIndex, out endIndex);
        if (resultCount == 0) break;
        //Marker信息
        e.Graphics.DrawString($"Marker {markerIndex}:  Start: {startIndex} End: {endIndex}",
            Font,
            Brushes.Red,
            200,
            height);
        height += 20;
        //每段Marker的点与类型信息
        for (int i = startIndex; i <= endIndex; i++)
        {
            e.Graphics.DrawString($"point {i}: ({potins[i].X},{potins[i].Y}) Type:{(int)types[i]}:{GetPathTypes((int)types[i])}",
                    Font,
                    Brushes.Black,
                    250,
                    height);
            height += 20;
        }
        markerIndex++;
    }

    myPath.ClearMarkers();
    pathIterator = new GraphicsPathIterator(myPath);
    pathIterator.Rewind();
    var count= pathIterator.NextMarker(out startIndex, out endIndex);
    //这里合成一个，0至19
}
/// <summary>
/// PathType转字符串
/// </summary>
/// <param name="pathType"></param>
/// <returns></returns>
private string GetPathTypes(int pathType)
{
    if (pathType == 0) return "0(起点)";
    List<string> typeStrs = new List<string>();
    while(true)
    {
        if(pathType >= 0x80)
        {
            typeStrs.Add("128(终点)");
            pathType -= 0x80;
        }
        else if (pathType >= 0x20)
        {
            typeStrs.Add("32(标记)");
            pathType -= 0x20;
        }
        else if (pathType >=0x7)
        {
            typeStrs.Add("7(屏蔽)");
            pathType -= 0x7;
        }
        else if(pathType >= 0x3)
        {
            typeStrs.Add("3(Bezier)");
            pathType -= 0x3;
        }
        else if (pathType >= 1)
        {
            typeStrs.Add("1(Line)");
            pathType -= 0x1;
        }
        if (pathType <= 0) break;
    }
    return string.Join("+",typeStrs.ToArray());
}

ClearMarkers清空标记

原型：

public void ClearMarkers ();

清除所有标记(Marker)，合并为一个。

StartFigure开始新的图形

原型：

public void StartFigure ();

在不封闭当前图形(路径)下，新开一个图形，后续增加的路径将在此图形中。

CloseAllFigures闭合所有图形、CloseFigure闭合当前图形

原型：

public void CloseAllFigures ();
public void CloseFigure ();

CloseAllFigures ：闭合该路径中所有开放的图形并开始一个新图形。它通过从端点到起点连接一条线来闭合每个开放图形。
CloseFigure：闭合当前图形并开始新图形。

// 创建含多个开放路径的图形
GraphicsPath myPath = new GraphicsPath();
myPath.StartFigure();
myPath.AddLine(new Point(10, 10), new Point(150, 10));
myPath.AddLine(new Point(150, 10), new Point(10, 150));
myPath.StartFigure();
myPath.AddArc(200, 200, 100, 100, 0, 90);
myPath.StartFigure();
Point point1 = new Point(300, 300);
Point point2 = new Point(400, 325);
Point point3 = new Point(400, 375);
Point point4 = new Point(300, 400);
Point[] points = { point1, point2, point3, point4 };
myPath.AddCurve(points);

// 绘制非封闭路径
e.Graphics.DrawPath(new Pen(Color.Green, 10), myPath);

// 封闭所有路径.
myPath.CloseAllFigures();

// 绘制封闭后路径
e.Graphics.DrawPath(new Pen(Color.Red, 1), myPath);


myPath = new GraphicsPath();
myPath.StartFigure();
myPath.AddLine(new Point(200, 10), new Point(400, 10));
myPath.AddLine(new Point(400, 10), new Point(400, 200));
myPath.CloseFigure();

e.Graphics.DrawPath(penRed, myPath);

【学习笔记】Windows GDI绘图目录