如何在Android TV上移动网格项目？

我正在为Android TV开发一个网格界面（使用

VerticalGridSupportFragment

），我正在寻找一种允许用户在网格中移动项目的方法

其想法是网格包含许多电视频道，用户应该能够更改电视频道的顺序（排序/重新排序）。我建议的解决方案是通过单击来选择频道。然后通道变得“粘滞”，允许您移动它。当您对该位置满意时，再次单击频道，确认其新位置

显而易见的解决办法是按照以下思路做一些事情：

getVerticalGridView()?.let { 
    it.setOnChildSelectedListener { _, _, position, _ ->
        // Move the item in the previous position to the new position
        adapter.move(oldPosition, position)

        // Set old position to currently selected position.
        oldPosition = position
    }
}

fun VerticalGridSupportFragment.getVerticalGridView(): VerticalGridView? {
    return VerticalGridSupportFragment::class.java.getDeclaredField("mGridViewHolder")?.let {
        it.isAccessible = true
        return (it.get(this) as VerticalGridPresenter.ViewHolder).gridView
    }
}

问题是，

adapter.move（）

会导致另一个选中的子事件

我试图通过临时删除选择侦听器来避免此问题，而是保留一个ObjectAdapter.DataObserver来通知我

onItemMoved（）

事件，在这些事件中，我设置了所选位置并再次设置了选择侦听器

这似乎也不完全有效

不可能使用

ItemTouchHelper

，因为它是为触摸而设计的，并且不像我们在安卓电视上那样使用遥控器

---

当你在主屏幕上重新排列应用程序快捷方式时，官方的Android TV launcher应用程序正在做一些类似于我所需要的事情，但我想不出一个方法来让它工作。

找到了一个解决方案，这似乎也是谷歌在Android TV launcher上使用的方法

简而言之：创建一个自定义的

VerticalGridView

并覆盖其

focusSearch（）

方法来确定如何移动/交换项目

类似于此：

class EditableVerticalGridView @JvmOverloads constructor(context: Context,
                                                         attrs: AttributeSet? = null,
                                                         defStyle: Int = 0) :
        VerticalGridView(context, attrs, defStyle) {

    override fun focusSearch(focused: View, direction: Int): View {
        return if (focused.isSelected) {
            swapItemsIfNeeded(focused, direction)
        } else super.focusSearch(focused, direction)
    }

    private fun swapItemsIfNeeded(focused: View, direction: Int): View {
        val position = getChildAdapterPosition(focused)
        if (!itemAnimator.isRunning) {
            if (canMoveInDirection(position, direction)) {
                when (direction) {
                    FOCUS_LEFT -> moveChannel(position, position - 1)
                    FOCUS_UP -> moveChannel(position, position - NUM_COLUMN)
                    FOCUS_RIGHT -> moveChannel(position, position + 1)
                    FOCUS_DOWN -> moveChannel(position, position + NUM_COLUMN)
                }
            }
        }
        return focused
    }

    private fun canMoveInDirection(position: Int, direction: Int): Boolean {
        when (direction) {
            FOCUS_LEFT -> {
                return position % NUM_COLUMN > 0
            }
            FOCUS_UP -> {
                return position - NUM_COLUMN >= 0
            }
            FOCUS_RIGHT -> {
                return !(position % NUM_COLUMN >= (NUM_COLUMN - 1) ||
                        position >= adapter.itemCount - 1)
            }
            FOCUS_DOWN -> {
                return position + NUM_COLUMN <= adapter.itemCount - 1
            }
            else -> {
                return false
            }
        }
    }

    private fun moveChannel(fromPosition: Int, toPosition: Int) {
        (adapter as AllowedChannelAdapter).moveChannel(fromPosition, toPosition)
    }

    companion object {

        private const val NUM_COLUMN: Int = 6

    }

}

fun moveChannel(from: Int, to: Int) {
        var offset = 1
        if (from >= 0 && from <= channelItems.size - 1 && to >= 0 && to <= channelItems.size - 1) {
            val fromItem = channelItems[from]
            channelItems[from] = channelItems[to]
            channelItems[to] = fromItem
            notifyItemMoved(from, to)

            val positionDifference = to - from
            if (Math.abs(positionDifference) > 1) {
                if (positionDifference > 0) {
                    offset = -1
                }
                notifyItemMoved(to + offset, from)
            }
        }
    }