costum itemdecoration

CardStackSpacingItemDecoration.kt

import android.content.res.Resources
import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.RecyclerView

class CardStackSpacingItemDecoration : RecyclerView.ItemDecoration() {

    private val dp = Resources.getSystem().displayMetrics.density

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view)

        if (position != 0)
            outRect.top = (-24 * dp).toInt()
    }
}

GridSpacingItemDecoration.kt

import android.content.res.Resources
import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.RecyclerView
import com.thoughtbot.expandablerecyclerview.models.ExpandableListPosition


class GridSpacingItemDecoration(
    private val spanCount: Int, private val spacing: Int
) : RecyclerView.ItemDecoration() {

    private val dp = Resources.getSystem().displayMetrics.density

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view) // item position

        if(parent.adapter?.getItemViewType(position) == ExpandableListPosition.CHILD){

            val paddingHorizontal = (8 * dp).toInt()
            val paddingBottom = (16 * dp).toInt()
            outRect.left = paddingHorizontal
            outRect.right = paddingHorizontal
            outRect.bottom = paddingBottom
        }else{
            val paddingHorizontal = (8 * dp).toInt()
            outRect.right = paddingHorizontal
        }

    }
}

HorizontalSpacingItemDecoration.kt

import android.content.res.Resources
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.Rect
import android.view.View
import android.view.animation.AccelerateDecelerateInterpolator
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView


class HorizontalSpacingItemDecoration : RecyclerView.ItemDecoration() {

    private val colorActive = Color.parseColor("#f6932c")
    private val colorInactive = Color.parseColor("#e7e7eb")

    private val dp = Resources.getSystem().displayMetrics.density

    /**
     * Height of the space the indicator takes up at the bottom of the view.
     */
    private val mIndicatorHeight = dp * 8

    /**
     * Indicator stroke width.
     */
    private val mIndicatorStrokeWidth = dp * 4

    /**
     * Indicator width.
     */
    private val mIndicatorItemLength = dp * 4

    /**
     * Padding between indicators.
     */
    private val mIndicatorItemPadding = dp * 8

    /**
     * Some more natural animation interpolation
     */
    private val mInterpolator = AccelerateDecelerateInterpolator()


    private val mPaint = Paint()

    init {
        mPaint.strokeWidth = mIndicatorStrokeWidth
        mPaint.style = Paint.Style.STROKE
        mPaint.isAntiAlias = true
    }

    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
        super.onDraw(c, parent, state)
        val itemCount = parent.adapter?.itemCount ?:0

        // center horizontally, calculate width and subtract half from center
        val totalLength = mIndicatorItemLength * itemCount
        val paddingBetweenItems = Math.max(0, itemCount - 1) * mIndicatorItemPadding
        val indicatorTotalWidth = totalLength + paddingBetweenItems
        val indicatorStartX = (parent.width - indicatorTotalWidth) / 2f

        // center vertically in the allotted space
        val indicatorPosY = parent.height - mIndicatorHeight / 2f

        drawInactiveIndicators(c, indicatorStartX, indicatorPosY, itemCount)

        // find active page (which should be highlighted)
        val layoutManager = parent.layoutManager as LinearLayoutManager
        val activePosition = layoutManager.findFirstVisibleItemPosition()
        if (activePosition == RecyclerView.NO_POSITION) {
            return
        }

        // find offset of active page (if the user is scrolling)
        val activeChild = layoutManager.findViewByPosition(activePosition)
        val left = activeChild?.left ?:0
        val width = activeChild?.width ?:0

        // on swipe the active item will be positioned from [-width, 0]
        // interpolate offset for smooth animation
        val progress = mInterpolator.getInterpolation(left * -1 / width.toFloat())

        drawHighlights(c, indicatorStartX, indicatorPosY, activePosition, progress)

    }


    private fun drawInactiveIndicators(c: Canvas, indicatorStartX: Float, indicatorPosY: Float, itemCount: Int) {
        mPaint.color = colorInactive

        // width of item indicator including padding
        val itemWidth = mIndicatorItemLength + mIndicatorItemPadding

        var start = indicatorStartX
        for (i in 0 until itemCount) {

            c.drawCircle(start, indicatorPosY, mIndicatorItemLength / 2f, mPaint)

            start += itemWidth
        }
    }


    private fun drawHighlights(c: Canvas, indicatorStartX: Float, indicatorPosY: Float,
                               highlightPosition: Int, progress: Float) {
        mPaint.color = colorActive

        // width of item indicator including padding
        val itemWidth = mIndicatorItemLength + mIndicatorItemPadding

        if (progress == 0f) {
            // no swipe, draw a normal indicator
            val highlightStart = indicatorStartX + itemWidth * highlightPosition

            c.drawCircle(highlightStart, indicatorPosY, mIndicatorItemLength / 2f, mPaint)

        } else {
            val highlightStart = indicatorStartX + itemWidth * highlightPosition
            // calculate partial highlight
            val partialLength = mIndicatorItemLength * progress + mIndicatorItemPadding * progress

            c.drawCircle(highlightStart + partialLength, indicatorPosY, mIndicatorItemLength / 2f, mPaint)
        }
    }

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val leftPadding = (24 * dp).toInt()
        val rightPadding = (16 * dp).toInt()
        parent.clipToPadding = false
        parent.setPadding(leftPadding, 0, rightPadding, 0)
        outRect.right = (8 * dp).toInt()
        outRect.bottom = (16 * dp).toInt()
    }
}