监听键盘弹起，在键盘上面悬浮视图

gistfile1.txt

import android.app.Activity
import android.content.Context
import android.graphics.Rect
import android.support.constraint.ConstraintLayout
import android.util.AttributeSet
import android.view.Gravity
import android.view.View
import android.view.ViewGroup
import android.view.ViewGroup.LayoutParams.WRAP_CONTENT
import android.widget.FrameLayout

/**
 * 输入法上悬浮框（没有使用单独的window实现，直接加在原有的decor view内）
 */
open class InputFloatView @JvmOverloads constructor(context: Context, attributeSet: AttributeSet? = null, defThemeInt: Int = 0)
    : ConstraintLayout(context, attributeSet, defThemeInt) {

    var activity: Activity? = null

    var isListening = true
    open var customInputViewThreshold: Int? = null
    open var needFixStatusBar: Boolean = false
    private var listener: ((view: View, isShow: Boolean, inputViewHeight: Int) -> Unit)? = null

    init {
        if (context is Activity) {
            register(context)
        }
    }

    fun register(activity: Activity, needFixStatusBar: Boolean = false) {

        this.activity = activity
        val decorView = activity.window.decorView
        this.needFixStatusBar = needFixStatusBar
        decorView.viewTreeObserver.addOnGlobalLayoutListener {
            if (!isListening) {
                return@addOnGlobalLayoutListener
            }
            val r = Rect()
            // 注意我们是沉浸式的页面，这个地方会少算一个status bar的高度
            decorView.getWindowVisibleDisplayFrame(r)
            val screenHeight = decorView.height
            val heightDifference = screenHeight - (r.bottom - r.top)
            // todo 能不能主动获取是否是沉浸式的页面？
            val fixStatusBar = if (this.needFixStatusBar) {
                getStatusHeight()
            } else {
                0
            }
            if (this.parent == null) {
                val layoutParams = initLayoutParams()
                layoutParams.gravity = Gravity.BOTTOM
                (decorView as? ViewGroup)?.addView(this, layoutParams)
            }
            if (heightDifference > customInputViewThreshold ?: INPUT_VIEW_THRESHOLD) {
                val inputViewHeight = heightDifference - fixStatusBar
                (this.layoutParams as? ViewGroup.MarginLayoutParams)?.bottomMargin = inputViewHeight
                this.visibility = View.VISIBLE
                this.listener?.invoke(this, true, heightDifference)
            } else {
                this.visibility = View.GONE
                this.listener?.invoke(this, false, heightDifference)
            }
        }
    }

    fun setOnInputViewToggleListener(listener: ((view: View, isShow: Boolean, inputViewHeight: Int) -> Unit)?) {
        this.listener = listener
    }

    open fun initLayoutParams(): FrameLayout.LayoutParams = FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT)

    companion object {

        /**
         * 随便写了个输入法高度阈值
         */
        const val INPUT_VIEW_THRESHOLD = 800

    }

}