【学习笔记】Windows GDI绘图(七)图形路径GraphicsPath详解(下)

文章目录

前三篇回顾
GraphicsPath方法
- Flatten压平(将曲线转成线段)
- GetBounds获取外接矩形
- GetLastPoint获取路径最后一个点
- IsOutlineVisible
- IsVisiable是否在轮廓上或内部
- Reset重置
- Reverse逆转点的顺序
- Transform矩阵变换
- Wrap扭曲变换
- Widen将路径替换为指定画笔的填充区域

前三篇回顾

【学习笔记】Windows GDI绘图(五)图形路径GraphicsPath详解(上)

图形路径GraphicsPath
填充模式FillMode
构造函数
GraphicsPath()
GraphicsPath(FillMode)
GraphicsPath(Point[],Byte[])和GraphicsPath(PointF[], Byte[])
GraphicsPath(Point[], Byte[], FillMode)和GraphicsPath(PointF[], Byte[], FillMode)
PathPointType
属性
FillMode
PathData
PathPoints、PathTypes
PointCount
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添加基数样条曲线(开放)
AddEllipse添加椭圆
AddLine添加线段

【学习笔记】Windows GDI绘图(六)图形路径GraphicsPath详解(中)

AddLines添加线段
AddPath附加路径
AddPie添加饼形
AddPolygon添加多边形
AddRectangle和AddRectangles 添加矩形
AddString添加字符串
SetMarkers设置标记
ClearMarkers清空标记
StartFigure开始新的图形
CloseAllFigures闭合所有图形、CloseFigure闭合当前图形

Window GDI+ API有BUG?GetBounds测不准？

详细说明GetBounds方法
全文图像

GraphicsPath方法

Flatten压平(将曲线转成线段)

原型：

public void Flatten ();
public void Flatten (System.Drawing.Drawing2D.Matrix? matrix);//默认flatness=0.25
public void Flatten (System.Drawing.Drawing2D.Matrix? matrix, float flatness);

参数	说明
martix	变换矩阵
flatness	曲线转线段的最大误差，默认值是0.25。值越小，越接近曲线，线段数量越多。

将此路径中的每条曲线转换为一系列连接的线段。

GraphicsPath myPath = new GraphicsPath();
Matrix translateMatrix = new Matrix();
translateMatrix.Translate(0, 0);
Point point1 = new Point(20, 200);
Point point2 = new Point(100, 30);
Point point3 = new Point(230, 300);
Point point4 = new Point(380, 150);
Point[] points = { point1, point2, point3, point4 };
myPath.AddCurve(points);

e.Graphics.DrawPath(new Pen(Color.LightGreen, 5), myPath);
myPath.Flatten(translateMatrix, 25f);
e.Graphics.DrawPath(new Pen(Color.Black, 1), myPath);

//原曲线控制点
foreach (var pt in points)
{
    e.Graphics.FillEllipse(Brushes.Red, pt.X - 5, pt.Y - 5, 10, 10);
}

//Flatten后的点
foreach( var pt in myPath.PathPoints )
{
    e.Graphics.FillEllipse(Brushes.Black, pt.X - 3, pt.Y - 3, 6, 6);
}

Flatten

GetBounds获取外接矩形

原型：

public System.Drawing.RectangleF GetBounds ();
public System.Drawing.RectangleF GetBounds (System.Drawing.Drawing2D.Matrix? matrix);
public System.Drawing.RectangleF GetBounds (System.Drawing.Drawing2D.Matrix? matrix, System.Drawing.Pen? pen);

获取路径的外接矩形，关于使用pen参数后，获取结果貌似“松弛”问题，可查阅Window GDI+ API有BUG?GetBounds测不准？

var rect = new Rectangle(200, 200, 300, 200);

using(var path=new GraphicsPath())
{
    path.AddEllipse(rect);

    //用于确定椭圆的矩形
    e.Graphics.DrawRectangle(new Pen(Color.LightGreen,10),rect);

    var pathPen = new Pen(Color.Green, 50);
    pathPen.MiterLimit = 1;

    var bboxWithPen = path.GetBounds(new Matrix(), pathPen);
    //含pen参数的外接矩形
    e.Graphics.DrawRectangle(Pens.Black,
                             bboxWithPen.X + pathPen.Width / 2, 
                             bboxWithPen.Y + pathPen.Width / 2, 
                             bboxWithPen.Width - pathPen.Width, 
                             bboxWithPen.Height - pathPen.Width);


    //绘制椭圆
    e.Graphics.DrawPath(pathPen, path);

    var bboxWitoutPen = path.GetBounds();

    //不含pen参数的外接矩形
    e.Graphics.DrawRectangles(new Pen(Color.Red, 3), new RectangleF[] { bboxWitoutPen });
}

定义一个矩形，根据这个矩形绘制一个椭圆，其中pen的宽度为50，获取含pen与不含pen时其外接矩形的大小。
GetBounds

GetLastPoint获取路径最后一个点

原型：

public System.Drawing.PointF GetLastPoint ();

作用：获取GraphicsPath中路径的最后一个点。

var pt1 = new Point(200, 200);
var pt2 = new Point(300, 300);

using (var path = new GraphicsPath())
{
    path.AddLine(pt1,pt2);

    //绘制路径
    e.Graphics.DrawPath(new Pen(Color.Red, 10), path);

    //获取路径最后一个点的坐
    var lastPoint=path.GetLastPoint();
    int offset = 20;
    //显示最后一点的坐标
    DrawString(e, $"LastPoint:({lastPoint.X},{lastPoint.Y})", ref offset);
}

定义两个点，按线段方式添加到图形路径中，再通过GetLastPoint()获取其最后一个点的坐标。

在这里插入图片描述

IsOutlineVisible

原型：

public bool IsOutlineVisible (int x, int y, System.Drawing.Pen pen, System.Drawing.Graphics? graphics);
public bool IsOutlineVisible (System.Drawing.Point pt, System.Drawing.Pen pen, System.Drawing.Graphics? graphics);
public bool IsOutlineVisible (float x, float y, System.Drawing.Pen pen, System.Drawing.Graphics? graphics);
public bool IsOutlineVisible (float x, float y, System.Drawing.Pen pen);
public bool IsOutlineVisible (System.Drawing.PointF point, System.Drawing.Pen pen);
public bool IsOutlineVisible (System.Drawing.PointF pt, System.Drawing.Pen pen, System.Drawing.Graphics? graphics);
public bool IsOutlineVisible (int x, int y, System.Drawing.Pen pen);
public bool IsOutlineVisible (System.Drawing.Point point, System.Drawing.Pen pen);

作用：使用指定的Pen绘制时，指定的点是否包含在此GraphicsPath的轮廓内。
要判断的点在边缘处时，不同的笔宽返回值略有不同，使用时需注意。

[System.ComponentModel.Description("GraphicsPath的IsOutlineVisiable方法")]
public void Demo07_04(PaintEventArgs e)
{
    var rect = new Rectangle(300, 200, 300, 200);

    using (var path = new GraphicsPath(FillMode.Winding))
    {
        path.AddRectangle(rect);

        var penWidth = 1f;
        var halfPenWidth = penWidth / 2f;

        var pathPen = new Pen(Color.Red, penWidth);

        //绘制路径
        e.Graphics.DrawPath(pathPen, path);
        int offset = 10;
        DrawString(e,$"Rect:({rect.X},{rect.Y},{rect.Width},{rect.Height}) penWidth:{pathPen.Width}",ref offset);
        var y = (rect.Top + rect.Bottom) / 2.0f;

        var pt = new PointF(rect.X - halfPenWidth - 1f, y);
        DrawString(e, $"({pt.X},{pt.Y}) IsOutlineVisiable:{path.IsOutlineVisible(pt, pathPen)})", ref offset);
        DrawCross(e, pt, Color.Black);

        pt = new PointF(rect.X - halfPenWidth-0.5f, y);
        DrawString(e, $"({pt.X},{pt.Y}) IsOutlineVisiable:{path.IsOutlineVisible(pt, pathPen)})", ref offset);
        DrawCross(e, pt, Color.Black);

        pt = new PointF(rect.X + halfPenWidth - 1f, y);
        DrawString(e, $"({pt.X},{pt.Y}) IsOutlineVisiable:{path.IsOutlineVisible(pt, pathPen)})", ref offset);
        DrawCross(e, pt, Color.Black);

        pt = new PointF(rect.X + halfPenWidth - 0.5f, y);
        DrawString(e, $"({pt.X},{pt.Y}) IsOutlineVisiable:{path.IsOutlineVisible(pt, pathPen)})", ref offset);
        DrawCross(e, pt, Color.Black);

        pt = new Point(450, 300);
        // 在轮廓包围的里面，也不算在轮廓上
        DrawString(e, $"({pt.X},{pt.Y}) IsOutlineVisiable:{path.IsOutlineVisible(pt, pathPen)})", ref offset);
        DrawCross(e, pt, Color.Black);
    }
}

/// <summary>
/// 给定中心点，画十字架
/// </summary>
/// <param name="e"></param>
/// <param name="center"></param>
/// <param name="color"></param>
/// <param name="len"></param>
/// <param name="penWidth"></param>
private void DrawCross(PaintEventArgs e,PointF center,Color color, int len=40, float penWidth=1f)
{
    var half = len / 2.0f;
    using (var pen = new Pen(color, penWidth))
    {
        e.Graphics.DrawLine(pen, center.X, center.Y - half, center.X, center.Y + half);
        e.Graphics.DrawLine(pen, center.X-half, center.Y, center.X+half, center.Y );
    }
}

笔宽为1时
在这里插入图片描述
笔宽为10时

IsVisiable是否在轮廓上或内部

原型：

public bool IsVisible (System.Drawing.Point point);
public bool IsVisible (System.Drawing.PointF point);
public bool IsVisible (System.Drawing.Point pt, System.Drawing.Graphics? graphics);
public bool IsVisible (System.Drawing.PointF pt, System.Drawing.Graphics? graphics);
public bool IsVisible (int x, int y);
public bool IsVisible (float x, float y);
public bool IsVisible (int x, int y, System.Drawing.Graphics? graphics);
public bool IsVisible (float x, float y, System.Drawing.Graphics? graphics);

作用：判断一个点是否在轮廓上或内部（与IsOutlineVisiable的差别时，IsOutlineVisable只判断是在轮廓上)，如果路径是未封闭图形，会自动封闭？

        [System.ComponentModel.Description("GraphicsPath的IsVisiable方法")]
        public void Demo07_05(PaintEventArgs e)
        {
            var rect = new Rectangle(300, 200, 300, 200);

            using (var path = new GraphicsPath(FillMode.Winding))
            {
                path.AddRectangle(rect);

                var penWidth = 10f;
                var halfPenWidth = penWidth / 2f;

                var pathPen = new Pen(Color.Red, penWidth);

                //绘制路径
                e.Graphics.DrawPath(pathPen, path);
                int offset = 10;
                DrawString(e, $"Rect:({rect.X},{rect.Y},{rect.Width},{rect.Height}) penWidth:{pathPen.Width}", ref offset);
                var y = (rect.Top + rect.Bottom) / 2.0f;

                var pt = new PointF(rect.X - halfPenWidth - 1f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X - halfPenWidth - 0.5f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X + halfPenWidth - 1f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X + halfPenWidth - 0.5f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new Point(450, 300);
                // 在轮廓包围的里面，也不算在轮廓上
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);
            }
        }

        [System.ComponentModel.Description("GraphicsPath的IsVisiable方法")]
        public void Demo07_06(PaintEventArgs e)
        {
            var rect = new Rectangle(300, 200, 300, 200);
            var pts = new Point[]
            {
                new Point(300,400),
                new Point(400,150),
                new Point(500,420)
            };

            using (var path = new GraphicsPath(FillMode.Winding))
            {
                path.AddCurve(pts);

                var penWidth = 10f;
                var halfPenWidth = penWidth / 2f;

                var pathPen = new Pen(Color.Red, penWidth);

                //绘制路径
                e.Graphics.DrawPath(pathPen, path);
                int offset = 10;
                DrawString(e, $"Rect:({rect.X},{rect.Y},{rect.Width},{rect.Height}) penWidth:{pathPen.Width}", ref offset);
                var y = (rect.Top + rect.Bottom) / 2.0f;

                var pt = new PointF(rect.X - halfPenWidth - 1f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X - halfPenWidth - 0.5f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X + halfPenWidth - 1f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new PointF(rect.X + halfPenWidth - 0.5f, y);
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);

                pt = new Point(450, 300);
                // 在轮廓包围的里面，也不算在轮廓上
                DrawString(e, $"({pt.X},{pt.Y}) IsVisible:{path.IsVisible(pt)})", ref offset);
                DrawCross(e, pt, Color.Black);
            }
        }

创建一个矩形和一个开放的曲线，判断点。

IsVisiable
IsVisable

Reset重置

原型：

public void Reset ();

作用：清空路径并将FillMode置为Alternate。

Reverse逆转点的顺序

原型：

public void Reverse ();

作用：逆转GraphicsPath中PathPoints的点的顺序。

var rect = new Rectangle(200, 200, 400, 250);
var pts = new Point[]
{
    new Point(300,400),
    new Point(400,150),
    new Point(500,420)
};

using (var path = new GraphicsPath(FillMode.Winding))
{
    path.AddRectangle(rect);
    path.AddCurve(pts);

    var penWidth = 10f;

    var pathPen = new Pen(Color.Red, penWidth);

    //绘制路径
    e.Graphics.DrawPath(pathPen, path);

    //逆转
    path.Reverse();

    e.Graphics.DrawPath(Pens.Black, path);
}

Reverse

Transform矩阵变换

原型：

public void Transform (System.Drawing.Drawing2D.Matrix matrix);

作用：应用一个矩阵变换到GraphicsPath中

var rect = new Rectangle(200, 200, 300, 200);        

using (var path = new GraphicsPath(FillMode.Winding))
{
    path.AddRectangle(rect);
    //原始矩形
    e.Graphics.DrawPath(Pens.Red,path);

    var matrix = new Matrix();
    //向右、向下各偏移100
    matrix.Translate(100, 100, MatrixOrder.Append);
    path.Transform(matrix);
    e.Graphics.DrawPath(Pens.Black, path);

    matrix.Reset();
    //缩小0.5倍
    matrix.Scale(0.5f, 0.5f, MatrixOrder.Append);
    path.Transform(matrix);
    e.Graphics.DrawPath(Pens.LightGreen, path);
}

定义一个矩形，先向右、向左平移，再缩小0.5倍
Transform

Wrap扭曲变换

原型：

public void Warp (System.Drawing.PointF[] destPoints, System.Drawing.RectangleF srcRect);
public void Warp (System.Drawing.PointF[] destPoints, System.Drawing.RectangleF srcRect, System.Drawing.Drawing2D.Matrix? matrix);
public void Warp (System.Drawing.PointF[] destPoints, System.Drawing.RectangleF srcRect, System.Drawing.Drawing2D.Matrix? matrix, System.Drawing.Drawing2D.WarpMode warpMode);
public void Warp (System.Drawing.PointF[] destPoints, System.Drawing.RectangleF srcRect, System.Drawing.Drawing2D.Matrix? matrix, System.Drawing.Drawing2D.WarpMode warpMode, float flatness);

作用：通过定义目标平行四边形的三个顶点（左上角、右上角和左下角）或四边形的四个顶点来扭曲GraphicsPath中的路径。

var srcRect = new Rectangle(200, 200, 300, 200);
Point point1 = new Point(20, 200);
Point point2 = new Point(100, 30);
Point point3 = new Point(230, 300);
Point point4 = new Point(380, 150);
Point[] points = { point1, point2, point3, point4 };

using (var path = new GraphicsPath(FillMode.Winding))
{

    path.AddCurve(points);
    path.AddRectangle(srcRect);
    //原始矩形
    e.Graphics.DrawPath(new Pen(Color.Red,3), path);

    //定义平行四边形三个顶点（左上角、右上角、左下角）
    var destPtList = new List<PointF>()
    {
        new PointF(300,300),
        new PointF(600,250),
        new PointF(200,450)
    };

    // Create a translation matrix.
    Matrix translateMatrix = new Matrix();
    // Warp the source path (rectangle).

    path.Warp(destPtList.ToArray(), srcRect, translateMatrix, WarpMode.Perspective, 0.5f);
    e.Graphics.DrawPath(new Pen(Color.LightGreen, 3), path);

    //加一个点，自定义四边形
    destPtList.Add(new PointF(550, 450));
    //需要重置，不重置的话，是在前面warp变换后，再次变换
    path.Reset();
    path.AddCurve(points);
    path.AddRectangle(srcRect);
    path.Warp(destPtList.ToArray(), srcRect, translateMatrix, WarpMode.Perspective, 0.5f);
    e.Graphics.DrawPath(new Pen(Color.LightBlue, 3), path);

    //
    path.Reset();
    path.AddCurve(points);
    path.AddRectangle(srcRect);
    translateMatrix.Translate(100, 50);
    path.Warp(destPtList.ToArray(), srcRect, translateMatrix, WarpMode.Perspective, 0.5f);
    e.Graphics.DrawPath(new Pen(Color.Pink, 3), path);

}

Wrap

Widen将路径替换为指定画笔的填充区域

原型：

public void Widen (System.Drawing.Pen pen, System.Drawing.Drawing2D.Matrix? matrix);
public void Widen (System.Drawing.Pen pen);
public void Widen (System.Drawing.Pen pen, System.Drawing.Drawing2D.Matrix? matrix, float flatness);

作用：将路径替换为指定画笔的填充区域（类似获取膨胀后的轮廓）

 // 创建两个正方形.
 GraphicsPath myPath = new GraphicsPath();
 myPath.AddRectangle(new Rectangle(300, 100, 100, 100));
 myPath.AddRectangle(new Rectangle(450, 100, 100, 100));

 // Draw the original ellipses to the screen in black.
 e.Graphics.DrawPath(Pens.Black, myPath);

 int offset = 5;
 DrawString(e, $"Src PointCount={myPath.PointCount}", ref offset);
 for(int i=0;i<myPath.PointCount;i++)
 {
     var pt = myPath.PathPoints[i];
     var type = myPath.PathTypes[i];
     DrawString(e, $"\tPoint:({pt.X},{pt.Y}),types:{type}", ref offset);
 }

 // Widen the path.
 Pen widenPen = new Pen(Color.Black, 20);
 Matrix widenMatrix = new Matrix();
 //widenMatrix.Translate(50, 50);
 myPath.Widen(widenPen, widenMatrix, 1.0f);

 //绘制Widden后的路径
 e.Graphics.DrawPath(new Pen(Color.Red,3), myPath);
 //这里用FillPath
 e.Graphics.FillPath(new SolidBrush(Color.FromArgb(127,Color.LightGreen)), myPath);
  DrawString(e, $"Widen PointCount={myPath.PointCount}", ref offset);
 for (int i = 0; i < myPath.PointCount; i++)
 {
     var pt = myPath.PathPoints[i];
     var type = myPath.PathTypes[i];
     DrawString(e, $"\tPoint:({pt.X},{pt.Y}),types:{type}", ref offset);
     e.Graphics.FillEllipse(Brushes.Gold, pt.X - 3, pt.Y - 3, 6, 6);
 }