How to animate polyline on android?

Question

How to draw animated polyline on android google map? I had already implement trail library for animation. I want to create polyline as on Lyft on android.

Answer 1

Create two arraylist of latlng then create polyline by given method

private fun createPolyLine() {

        val lineOptions = PolylineOptions()
        lineOptions.width(6f)
        lineOptions.color(ContextCompat.getColor(act!!, R.color.colorPrimary))
        lineOptions.startCap(SquareCap())
        lineOptions.endCap(SquareCap())
        lineOptions.jointType(JointType.ROUND)
        blackPolyLine = googleMap!!.addPolyline(lineOptions)

        val greyOptions = PolylineOptions()
        greyOptions.width(6f)
        greyOptions.color(Color.GRAY)
        greyOptions.startCap(SquareCap())
        greyOptions.endCap(SquareCap())
        greyOptions.jointType(JointType.ROUND)
        greyPolyLine = googleMap!!.addPolyline(greyOptions)

        animatePolyLine()
    }

after that create animation of these polylines

private fun animatePolyLine() {
        val animator = ValueAnimator.ofInt(0, 100)
        animator.duration = 1500
        animator.interpolator = LinearInterpolator()
        animator.addUpdateListener { animator ->
            val latLngList =
                blackPolyLine!!.points
            val initialPointSize = latLngList.size
            val animatedValue = animator.animatedValue as Int
            val newPoints = animatedValue * decodedPath.size / 100
            if (initialPointSize < newPoints) {
                latLngList.addAll(decodedPath.subList(initialPointSize, newPoints))
                blackPolyLine!!.points = latLngList
            }
        }
        animator.addListener(polyLineAnimationListener)
        animator.start()
    }

private var polyLineAnimationListener: Animator.AnimatorListener =
        object : Animator.AnimatorListener {
            override fun onAnimationStart(animator: Animator) {}
            override fun onAnimationEnd(animator: Animator) {
                val blackLatLng: MutableList<LatLng> = blackPolyLine!!.points
                val greyLatLng: MutableList<LatLng> = greyPolyLine!!.points
                greyLatLng.clear()
                greyLatLng.addAll(blackLatLng)
                blackLatLng.clear()
                blackPolyLine!!.points = blackLatLng
                greyPolyLine!!.points = greyLatLng
                blackPolyLine!!.zIndex = 2f
                animator.start()
            }

            override fun onAnimationCancel(animator: Animator) {}
            override fun onAnimationRepeat(animator: Animator) {}
        }