kotlin自定义表盘实现教程

1.最近在学习kotlin的使用顺便自定义一个View做一下练习，废话不多说比较简单，直接上代码。

class DialPlateView :View {
    var str= listOf("300","600","900","计划值")
    var degree = 10f
    var h = object :Handler(){
        override fun handleMessage(msg: Message?) {
            var what = msg?.what
            if (what ==1) {
                degree++
                postInvalidateDelayed(50)
                if(degree>=90){
                    degree =-90f
                }
            }

        }
    }
    var colors = intArrayOf(Color.YELLOW,Color.GRAY,Color.GREEN,Color.BLUE,Color.CYAN)
    constructor(context:Context?) : this(context,null)
    constructor(context: Context?, attrs: AttributeSet?) : this(context, attrs, 0)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {

    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        var width = MeasureSpec.getSize(widthMeasureSpec)
        var height = MeasureSpec.getSize(heightMeasureSpec)
        var min = Math.min(width,height)
        setMeasuredDimension(min,min)
    }

    override fun onDraw(canvas: Canvas?) {
        var paint = Paint()
        paint.isAntiAlias = true
        drawBlackArc(canvas,paint)
        drawPoint(canvas,paint)
        drawRealArc(canvas,paint)
        drawRemindText(canvas,paint)
        drawSmallCircle(canvas,paint)
        drawSelectCircle(canvas,paint)
        drawVainArc(canvas,paint)
    }
    // 画虚线的圆弧
    fun drawVainArc(canvas: Canvas?,paint: Paint){
        paint.color=Color.RED
        paint.strokeWidth= ConvertUtils.dp2px(6.5f).toFloat()
        paint.style=Paint.Style.STROKE

        paint.strokeCap =Paint.Cap.ROUND
        var sweegrand = SweepGradient(measuredWidth/2f,measuredWidth/2f,colors,null)
        paint.shader = sweegrand
        var r = RectF(measuredWidth/10f,measuredHeight*1/10f,measuredWidth.toFloat()-measuredWidth/10,measuredHeight.toFloat()-measuredHeight/10)
        for (i in 0..3){
            when(i){
                0 -> canvas?.drawArc(r,180f,43f,false,paint)
                1 -> canvas?.drawArc(r,227f,41f,false,paint)
                2 -> canvas?.drawArc(r,272f,41f,false,paint)
                3 -> canvas?.drawArc(r,317f,43f,false,paint)

            }
        }

    }
    // 画指针的实心弧
    fun  drawRealArc(canvas: Canvas?,paint: Paint){
        paint.color=Color.RED
        paint.strokeWidth=1f
        paint.isAntiAlias = true
        paint.style=Paint.Style.FILL
        var pre = 0.45f
        for (i in 0..3){
            paint.color = Color.rgb(255*i/3,255*i/3,255*i/3)
            var r1 = RectF(measuredWidth*pre,measuredHeight*pre,measuredWidth.toFloat()-measuredWidth*pre,measuredHeight.toFloat()-measuredHeight*pre)
            canvas?.drawArc(r1,180f,180f,false,paint)
            pre +=0.01f

        }

    }
    // 画指针
    fun drawPoint(canvas: Canvas?,paint: Paint){
        paint.strokeWidth=ConvertUtils.dp2px(5f).toFloat()
        paint.color = Color.RED
        var Raduis = measuredWidth/2

        if (0<=degree&& degree<=90){
            var dx= Raduis*Math.cos((90 -degree)/180.0*Math.PI)
            var dy = Raduis *Math.sin((90 - degree)/180.0*Math.PI)
            var X = Raduis +0.15*dx
            var Y = Raduis -0.15*dy - paint.strokeWidth
            canvas?.drawLine(measuredWidth/2f,measuredWidth/2f-paint.strokeWidth,X.toFloat(),Y.toFloat(),paint)
        }
        if (degree<0 && degree>=-90){
            var dx = Raduis *Math.cos((90+degree)/180.0*Math.PI)
            var dy = Raduis *Math.sin((90+degree)/180.0*Math.PI)
            var X= Raduis - 0.15*dx
            var Y = Raduis - 0.15*dy -paint.strokeWidth
            canvas?.drawLine(measuredWidth/2f,measuredWidth/2f-paint.strokeWidth,X.toFloat(),Y.toFloat(),paint)
        }

        h.sendEmptyMessage(1)
    }
    fun drawBlackArc(canvas: Canvas?,paint: Paint){
        var innR = RectF(measuredWidth/5f,measuredWidth/5f,measuredWidth.toFloat() -measuredWidth/5,measuredWidth.toFloat() - measuredWidth/5f)
        paint.color= 0xFF393134.toInt()
        paint.style = Paint.Style.FILL
        canvas?.drawArc(innR,180f,180f,false,paint)
    }

    /*
    * 画文本
    * */
    fun drawRemindText(canvas: Canvas?,paint: Paint){
        paint.color = Color.WHITE
        paint.isAntiAlias = true
        paint.textSize =ConvertUtils.dp2px(14f).toFloat()
        paint.strokeWidth = ConvertUtils.dp2px(6f).toFloat()
        canvas?.save()
        for (i in 0..3){
            var width = paint.measureText(str[i])
            when(i){
                0-> canvas?.rotate(-45f,measuredWidth/2f,measuredWidth/2f)
                1,2-> canvas?.rotate(45f,measuredWidth/2f,measuredWidth/2f)
                3 -> canvas?.rotate(15f,measuredWidth/2f,measuredWidth/2f)
            }
            canvas?.drawText(str[i],measuredWidth/2f-width/2f,measuredWidth/2f-5*measuredWidth/12f,paint)
        }
        canvas?.restore()
    }

    /*
    * 绘制小圆球
    * */
    fun drawSmallCircle(canvas: Canvas?,paint: Paint){
        paint.strokeWidth = ConvertUtils.dp2px(10f).toFloat()
        paint.isAntiAlias = true
        paint.style=Paint.Style.FILL
        canvas?.save()
        for (i in 0..17){
            if (i==0){
                canvas?.rotate(0f,measuredWidth/2f,measuredWidth/2f)
            }else{
                canvas?.rotate(10.2f,measuredWidth/2f,measuredWidth/2f)
            }
            paint.color = Color.rgb(255*i/18,255*i/18,255*i/18)
            canvas?.drawCircle(measuredWidth*3/20f + ConvertUtils.dp2px(6.5f)/2,measuredWidth/2f-ConvertUtils.dp2px(6.5f),ConvertUtils.dp2px(6.5f).toFloat(),paint)

        }
        canvas?.restore()
    }

    /*
    * 绘制指针指向的小球
    * */
    fun drawSelectCircle(canvas: Canvas?,paint: Paint){
        paint.strokeWidth = ConvertUtils.dp2px(10f).toFloat()
        paint.isAntiAlias = true
        paint.style=Paint.Style.FILL
        canvas?.save()
        var num = (degree + 90) / 10
        for (i in 0..num.toInt()){
            if (i==0){
                canvas?.rotate(0f,measuredWidth/2f,measuredWidth/2f)
            }else{
                canvas?.rotate(10.2f,measuredWidth/2f,measuredWidth/2f)
            }
            paint.color = Color.RED
            canvas?.drawCircle(measuredWidth*3/20f + ConvertUtils.dp2px(6.5f)/2,measuredWidth/2f-ConvertUtils.dp2px(6.5f),ConvertUtils.dp2px(6.5f).toFloat(),paint)

        }
        canvas?.restore()
    }
}