Android Path详解

Path

路径，可用于绘制直线、曲线构成几何路径，还可以用于根据路径绘制文字。

常用api

移动、连线、闭合、添加图形等。

        //移动到某个点
        path.moveTo(100f,100f)

        //连线到绝对点
        path.lineTo(200f,200f)

        path.lineTo(250f,200f)

        //连线到相对上一个终点移动多少偏移量
        path.rLineTo(10f,30f)

        //添加曲线
        path.addArc(200f,200f,400f,400f,-220f,220f)

        //添加曲线
        path.addArc(200f,200f,400f,400f,-220f,220f)

        path.addRect(50f,50f,200f,200f,Path.Direction.CW)

        path.addCircle(50f,50f,100f,Path.Direction.CW)

        path.addOval(10f,10f,100f,200f,Path.Direction.CW)

        //闭合曲线
        path.close()

        canvas?.drawPath(path,paint)

addArc和arcTo的区别

        //添加曲线
        //Add the specified arc to the path as a new contour.
        //float left, float top, float right, float bottom, float startAngle, float sweepAngle
        path.addArc(200f,200f,400f,400f,-220f,220f)

        //Append the specified arc to the path as a new contour.
        //float left, float top, float right, float bottom, float startAngle,float sweepAngle, boolean forceMoveTo
        path.arcTo()

//arcTo多了一个参数，如果为false，那和addArc()效果一样，如果为true，
//那需要在前面path的终点加上一条直线连接到当前arc的起点，即自动lineTo()

其他功能：

        var path2 = Path()
        path2.moveTo(100f,100f)
        path2.lineTo(110f,100f)
        //添加另一条path
        path.addPath(path2)

        //添加圆角矩形
        var rect = RectF(200f,200f,300f,300f)
        path.addRoundRect(rect,20f,20f,Path.Direction.CW)

        //移动到某个点
        path.moveTo(300f,500f)
        //二阶贝塞尔曲线
        path.quadTo(500f,100f,800f,500f)
        //相对位置的二阶贝塞尔曲线
        path.rQuadTo(200f,-400f,500f,0f)

        //三阶贝塞尔曲线cubicTo(float x1, float y1, float x2, float y2, float x3, float y3)