ExpandableStackView

ExpandableStackView.kt

fun setAdapter(adapter: BaseAdapter) {

    val scene = MotionScene(this)

    val startSetId = View.generateViewId()
    val startSet = ConstraintSet()
    startSet.clone(this)

    val endSetId = View.generateViewId()
    val endSet = ConstraintSet()
    endSet.clone(this)

    val views = mutableListOf<View>()

    for (i in 0 until adapter.count) {

        val view = adapter.getView(i, null, this)
        val cardView = view.findViewById<CardView>(R.id.cardContainer)
        view.id = View.generateViewId()

        startSet.constrainHeight(view.id, ConstraintSet.WRAP_CONTENT)
        endSet.constrainHeight(view.id, ConstraintSet.WRAP_CONTENT)

        connectViewToParent(startSet, view)
        connectViewToParent(endSet, view)

        if (i == 0) {
            startSet.setCardElevation(cardView, 8f)
            endSet.setCardElevation(cardView, 4f)
            startSet.connect(
                view.id,
                ConstraintSet.TOP,
                ConstraintSet.PARENT_ID,
                ConstraintSet.TOP
            )
            endSet.connect(
                view.id,
                ConstraintSet.TOP,
                ConstraintSet.PARENT_ID,
                ConstraintSet.TOP
            )
        } else {

            if (i == 1) {
                startSet.setScaleX(
                    view.id,
                    0.95f
                )
                startSet.setCardElevation(cardView, 6f)
                endSet.setCardElevation(cardView, 4f)
            } else {
                startSet.setScaleX(
                    view.id,
                    0.9f
                )
                if (i == 2) {
                    startSet.setCardElevation(cardView, 4f)
                    endSet.setCardElevation(cardView, 4f)
                } else {
                    startSet.setCardElevation(cardView, 0f)
                    endSet.setCardElevation(cardView, 4f)
                }
            }

            views[i - 1].let {
                boundTwoViewEnd(endSet, it, view)
                if (i == adapter.count - 1) {
                    endSet.connect(
                        view.id,
                        ConstraintSet.BOTTOM,
                        ConstraintSet.PARENT_ID,
                        ConstraintSet.BOTTOM,
                        fromDpToPx(16).toInt()
                    )
                }

                boundTwoViewStart(
                    startSet, it, view,
                    if (i < 3)
                        fromDpToPx(8).toInt()
                    else
                        0
                )
            }
        }

        views.add(view)
    }

    views.asReversed().forEach {
        addView(it)
    }

    val transitionId = View.generateViewId()
    val transaction = TransitionBuilder.buildTransition(
        scene,
        transitionId,
        startSetId, startSet,
        endSetId, endSet
    )

    transaction.duration = 1000

    scene.addTransition(transaction)
    scene.setTransition(transaction)
    setScene(scene)

    setTransition(transitionId)
}