Circle View for Android in Kotlin

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

  <declare-styleable name="CircleView">
    <attr name="cv_color" format="color" />
  </declare-styleable>

</resources>

CircleView.kt

class CircleView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) {
  private val paint by lazy { Paint(Paint.ANTI_ALIAS_FLAG).apply { style = Paint.Style.FILL } }

  @ColorInt
  var color: Int = Color.TRANSPARENT
    set(value) {
      field = value
      invalidate()
    }

  init {
    attrs?.use(context, R.styleable.CircleView) {
      color = getColor(R.styleable.CircleView_cv_color, color)
    }
  }

  override fun onDraw(canvas: Canvas?) = super.onDraw(canvas).also {
    canvas?.drawCircle(width.div2float(), height.div2float(), min(width, height).div2float(), paint.apply {
      color = this@CircleView.color
    })
  }
}

private fun Int.div2float() = (this / 2).toFloat()

inline fun AttributeSet.use(context: Context, @StyleableRes attrs: IntArray, block: TypedArray.() -> Unit) {
  context.obtainStyledAttributes(this, attrs).use { typedArray -> block(typedArray) }
}