绘制箭头 - 爱码网

1，直接用平台库

Pen arrowPen = new Pen(Color.Blue);
arrowPen.Width = 4;
arrowPen.EndCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;

           Graphics gfx = this.pCanvas.CreateGraphics();
           gfx.DrawLine(arrowPen,
               5, 5,
               5, 100);

结果：

2，设置箭头样式

System.Drawing.Drawing2D.AdjustableArrowCap lineCap =
                new System.Drawing.Drawing2D.AdjustableArrowCap(6, 6, true);
            Pen redArrowPen = new Pen(Color.Red, 4);
            redArrowPen.CustomEndCap = lineCap;

            Graphics gfx = this.pCanvas.CreateGraphics();
            gfx.DrawLine(redArrowPen,
                25, 5,
                25, 100);

结果：

3，手动绘制

注意：代码中应用了，只用了其中的Vector2

//线的起点

PointF startPt = new PointF(100, 300);

//线的终点

PointF endPt = new PointF(200, 200);

//箭头的宽

float width = 10;

//箭头夹角

double angle = 60.0 / 180 * Math.PI;

//求BC长度

double widthBE = width / 2 / (Math.Tan(angle / 2));

//直线向量

Vector2 lineVector = new Vector2(endPt.X - startPt.X, endPt.Y - startPt.Y);

//单位向量

lineVector.Normalize();

//求BE向量

Vector2 beVector = (float)widthBE * -lineVector;

//求E点坐标

PointF ePt=new PointF();

//ePt - endPt = bcVector

ePt.X = endPt.X + beVector.X;

ePt.Y = endPt.Y + beVector.Y;

//因为CD向量和AB向量垂直,所以CD方向向量为

Vector2 cdVector = new Vector2(-lineVector.Y, lineVector.X);

//求单位向量

cdVector.Normalize();

//求CE向量

Vector2 ceVector = width / 2 * cdVector;

//求C点坐标,ePt - cPt = ceVector;

PointF cPt = new PointF();

cPt.X = ePt.X - ceVector.X;

cPt.Y = ePt.Y - ceVector.Y;

//求DE向量

Vector2 deVector = width / 2 * -cdVector;

//求D点,ePt-dPt = deVector;

PointF dPt = new PointF();

dPt.X = ePt.X - deVector.X;

dPt.Y = ePt.Y - deVector.Y;

//开始绘制

Graphics gfx = this.pCanvas.CreateGraphics();

//绘制线

gfx.DrawLine(Pens.Blue, startPt, endPt);

//绘制箭头

//gfx.DrawPolygon(Pens.Green,

//    new PointF[]{

//        cPt,dPt,endPt});

gfx.FillPolygon(Brushes.Green,

    new PointF[]{

        cPt,dPt,endPt});