如何以编程方式(在运行时)滑动RecyclerView的一行? [英] How to swipe one row of RecyclerView programatically (at run time)?

问题描述

我有一个RecyclerView，里面有这样的物品:

I have a RecyclerView with items inside like this:

我使用 ItemTouchHelper.SimpleCallback 侦听滑动，并且在滑动项目时使用onChildDraw()绘制画布:

I use ItemTouchHelper.SimpleCallback to listen for swipe and onChildDraw() to draw a canvas when items are swiped:

再次滑动:

我想在项目列表中的第一个项目上模拟一次滑动(在运行时)；我需要第一个项目在其X轴上移动(或多或少)-100像素，然后返回到原始位置.如何实现呢?

I want to simulate a swipe (at run time) just on first item inside the list of items; I need first item to go (more or less ) -100 px on its X axis and then go back to original position. How to achieve this?

推荐答案

我创建了一些实用程序方法，以防有人需要它

I created some utility method in case someone needs it

import android.animation.ValueAnimator
import android.os.SystemClock
import android.view.MotionEvent
import androidx.recyclerview.widget.ItemTouchHelper
import androidx.recyclerview.widget.RecyclerView

/**
 * @author Oleh Haidaienko
 * @since 29.07.2020
 */
object SwipeUtils {
    /**
     * Programmatically swipe RecyclerView item
     * @param recyclerView RecyclerView which item will be swiped
     * @param index Position of item
     * @param distance Swipe distance
     * @param direction Swipe direction, can be [ItemTouchHelper.START] or [ItemTouchHelper.END]
     * @param time Animation time in milliseconds
     */
    fun swipeRecyclerViewItem(
        recyclerView: RecyclerView,
        index: Int,
        distance: Int,
        direction: Int,
        time: Long
    ) {
        val childView = recyclerView.getChildAt(index) ?: return
        val x = childView.width / 2F
        val viewLocation = IntArray(2)
        childView.getLocationInWindow(viewLocation)
        val y = (viewLocation[1] + childView.height) / 2F
        val downTime = SystemClock.uptimeMillis()
        recyclerView.dispatchTouchEvent(
            MotionEvent.obtain(
                downTime,
                downTime,
                MotionEvent.ACTION_DOWN,
                x,
                y,
                0
            )
        )
        ValueAnimator.ofInt(0, distance).apply {
            duration = time
            addUpdateListener {
                val dX = it.animatedValue as Int
                val mX = when (direction) {
                    ItemTouchHelper.END -> x + dX
                    ItemTouchHelper.START -> x - dX
                    else -> 0F
                }
                recyclerView.dispatchTouchEvent(
                    MotionEvent.obtain(
                        downTime,
                        SystemClock.uptimeMillis(),
                        MotionEvent.ACTION_MOVE,
                        mX,
                        y,
                        0
                    )
                )
            }
        }.start()
    }
}

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