Kotlin自定义view的书写

优于别人，并不高贵，真正的高贵是优于过去的自己

直接上代码，这是manActivity的写法，实现接口，继承类用一个冒号就行了，不用像java一样再区分extends与implements了，intent中的写法也少许变化不是Activity.class而是Activity().javaClass

class MainActivity : BaseActivity(), View.OnClickListener {

lateinit var mTitleLeft: TextView
lateinit var mStart: TextView

override fun setContentView() {
    window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS)
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        window.statusBarColor = ContextCompat.getColor(this, R.color.titleColor)
    }
    setContentView(R.layout.activity_main)
}

override fun initView() {
    mTitleLeft = findViewById(R.id.mTitle_left)
    mTitleLeft.setOnClickListener(this)

    mStart = findViewById(R.id.mStart_tv)
    mStart.setOnClickListener(this)
}

override fun initData() {

}

//点击监听 Kotlin没有swich case 取而代之的是when表达式
override fun onClick(v: View?) {
    when (v!!.id) {
        R.id.mTitle_left -> finish()
        R.id.mStart_tv -> {
            //点击跳转
            var intent: Intent = Intent(this, StepActivity().javaClass)
            startActivity(intent)
        }
    }
}
}

下面是自定义view中的代码，构造函数之间的调用大家注意一下跟java的写法不一样，这种写法是第一个构造函数调用第二个，第二个调用第三个

class StepView : View {
//次数字体颜色
private var mStepColor: Int = Color.rgb(255, 255, 255)
//次数字体大小
private var mStepSize: Int = 0
//内部细圆颜色
private var inCircleColor: Int = Color.rgb(173, 173, 173)
//外部粗圆的开始颜色
private var outCircleStartColor: Int = Color.rgb(249, 183, 0)
//外部圆结束颜色
private var outCircleEndColor: Int = Color.rgb(246, 144, 5)
//时间字体颜色
private var mTimeColor: Int = Color.rgb(255, 255, 255)
//时间字体的大小
private var mTimeSize: Int = 10
//圆的宽高
private var mWidth: Int = 0
private var mHeight: Int = 0
//细圆的画笔
private lateinit var inPaint: Paint
//细圆的宽度
private var inRoundWidth: Int = 0
//粗圆的占比
private var maxNumber: Int = 100
private var nowNumber: Int = 0
//粗圆的画笔
private lateinit var outPaint: Paint
//粗圆的宽度
private var outRoundWidth: Int = 0
//画笔
private lateinit var mPaint: Paint
//数量
private var stepNumber: Int = 0
//是否更新步数
private var mIsClick: Boolean = true
//时间
private var mTime: String = "00:00:00"
//渐变数组
private var RoundColors: IntArray = intArrayOf(Color.rgb(249, 183, 0), Color.rgb(246, 144, 5), Color.rgb(249, 183, 0))


//继承三个构造方法
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) {
    var array: TypedArray = context!!.obtainStyledAttributes(attrs, R.styleable.StepView)
    mStepColor = array.getColor(R.styleable.StepView_mStepColor, mStepColor)
    mStepSize = array.getDimensionPixelSize(R.styleable.StepView_mStepSize, mStepSize)
    inCircleColor = array.getColor(R.styleable.StepView_inCircleColor, inCircleColor)
    outCircleStartColor = array.getColor(R.styleable.StepView_outCircleStartColor, outCircleStartColor)
    outCircleEndColor = array.getColor(R.styleable.StepView_outCircleEndColor, outCircleEndColor)
    mTimeColor = array.getColor(R.styleable.StepView_mTimeColor, mTimeColor)
    mTimeSize = array.getDimensionPixelSize(R.styleable.StepView_mTimeSize, mTimeSize)
    inRoundWidth = dp2px(context, 2)
    outRoundWidth = dp2px(context, 12)
}

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    mWidth = MeasureSpec.getSize(widthMeasureSpec)
    mHeight = MeasureSpec.getSize(heightMeasureSpec)
}

override fun onDraw(canvas: Canvas?) {
    super.onDraw(canvas)
    mPaint = Paint()

    var centerX: Int = mWidth / 2
    var centerY: Int = mHeight / 2

    mPaint.isAntiAlias = true
    mPaint.strokeWidth = inRoundWidth.toFloat()
    mPaint.color = inCircleColor
    mPaint.style = Paint.Style.STROKE
    canvas!!.drawCircle(centerX.toFloat(), centerY.toFloat(),
            (centerX - outRoundWidth).toFloat(), mPaint)

    mPaint.reset()
    mPaint.isAntiAlias = true
    mPaint.strokeWidth = outRoundWidth.toFloat()
    mPaint.color = outCircleEndColor
    mPaint.strokeCap = Paint.Cap.ROUND
    mPaint.strokeJoin = Paint.Join.ROUND
    var radius: Int = centerX - outRoundWidth
    var oval: RectF = RectF((centerX - radius).toFloat(), (centerY - radius).toFloat(),
            (centerX + radius).toFloat(), (centerY + radius).toFloat())
    var gradient: SweepGradient = SweepGradient(centerX.toFloat(), centerY.toFloat(), RoundColors, null)
    mPaint.shader = gradient
    var percent: Float = (nowNumber / maxNumber).toFloat()
    canvas.drawArc(oval, (-90).toFloat(), percent * 360, false, mPaint)

    //画次数
    mPaint.reset()
    mPaint.isAntiAlias = true
    mPaint.color = mStepColor
    mPaint.textSize = mStepSize.toFloat()
    var mStep = nowNumber.toString()
    var stepx: Int = ((mWidth - mPaint.measureText(stepNumber.toString())) / 2).toInt()
    var fontMetrics: Paint.FontMetrics = mPaint.fontMetrics
    var baseLine: Int = height / 2
    canvas.drawText(stepNumber.toString(), stepx.toFloat(), baseLine.toFloat(), mPaint)

    //画时间
    mPaint.reset()
    mPaint.isAntiAlias = true
    mPaint.color = mTimeColor
    mPaint.textSize = mTimeSize.toFloat()
    var dx: Int = ((width - mPaint.measureText(mTime + "")) / 2).toInt()
    var timeFontMetrics: Paint.FontMetrics = mPaint.fontMetrics
    var h: Int = height / 4
    var timeBaseLine: Int = (h * 3 + (timeFontMetrics.bottom - timeFontMetrics.top) / 2 - timeFontMetrics.bottom).toInt()
    canvas.drawText(mTime, dx.toFloat(), timeBaseLine.toFloat(), mPaint)


}


fun dp2px(context: Context, dpValue: Int): Int {
    var scale: Float = context.resources.displayMetrics.density
    return (dpValue * scale + 0.5f).toInt()
}

fun setNowNumber(number: Float, click: Boolean) {
    this.nowNumber = number.toInt()
    this.mIsClick = click
    invalidate()
}

//设置次数
fun setStepNumber(number: Int) {
    this.stepNumber = if (number > 999) 999 else number
}

//设置时间
fun setTime(time: String) {
    this.mTime = time
    invalidate()
}
}

这就是Kotlin的基本写法，这个只是界面呈现的代码，调用方法的代码还没写，待续
自定义view的样子如下图

IMG_20180704_181526.jpg