PHP短视频源码，按钮拖拽

bt.setOnTouchListener(object : OnTouchListener {
            //上次view的坐标位置
            internal var lastX: Int = 0
            internal var lastY: Int = 0
            var moveX = 0
            var moveY = 0
            var btnHeight = 0
            var btnWith = 0
            override fun onTouch(v: View, event: MotionEvent): Boolean {
                // TODO Auto-generated method stub
                val ea = event.action
                Log.i("TAG", "Touch:$ea")
                when (ea) {
                    MotionEvent.ACTION_DOWN -> {
                        //按下记录view坐标
                        lastX = event.rawX.toInt()
                        lastY = event.rawY.toInt()
                        btnHeight = bt.height
                        btnWith = bt.width
                    }
                    MotionEvent.ACTION_MOVE -> {
                        //移动时记录相对上次的坐标
                        val dx = event.rawX.toInt() - lastX
                        val dy = event.rawY.toInt() - lastY
                        moveX = dx
                        moveY = dy
                        //相对于parent 的View上下左右位置
                        var left = v.left + dx
                        var top = v.top + dy
                        var right = v.right + dx
                        var bottom = v.bottom + dy
                        //如果left < 0，则是左移，右边框上次位置加上左移部分
                        if (left < 0) {
                            left = 0
                            right = left + v.width
                        }
                        //
                        if (right > screenWidth) {
                            right = screenWidth
                            left = right - v.width
                        }
                        //如果top < 0，则是上移，下边框上次位置加上移部分
                        if (top < 0) {
                            top = 0
                            bottom = top + v.height
                        }
                        if (bottom > screenHeight) {
                            bottom = screenHeight
                            top = bottom - v.height
                        }
                        //重新layout
                        v.layout(left, top, right, bottom)
                        Log.i("", "position$left, $top, $right, $bottom")
                        lastX = event.rawX.toInt()
                        lastY = event.rawY.toInt()
                    }
                    MotionEvent.ACTION_UP -> {
                        isDrag = Math.abs(moveX) == 0 && Math.abs(moveY) == 0
                        // 向四周吸附
                        var dx1 = event.rawX - lastX
                        var dy1 =event.rawY - lastY
                        var left1 = v.left + btnWith/2  + dx1
                        var top1 = v.top + dy1
                        var right1 = v .right + dx1
                        var bottom1 = v .bottom + dy1
                        if (left1 < (screenWidth / 2)) {
//                            when {
//                                top1 < 100 -> v.layout(left1.toInt(), 0, right1.toInt(), btnHeight)
//                                bottom1 > (screenHeight - 200) -> v.layout(left1.toInt(), (screenHeight - btnHeight), right1.toInt(), screenHeight)
//                                else ->
//                                    v.layout(0, top1.toInt(), btnHeight, bottom1.toInt())
//                            }
                            v.layout(0, top1.toInt(), btnWith, bottom1.toInt())
                        } else {
//                            when {
//                                top1 < 100 -> v.layout(left1.toInt(), 0, right1.toInt(), btnHeight)
//                                bottom1 > (screenHeight - 200) -> v.layout(left1.toInt(), (screenHeight - btnHeight), right1.toInt(), screenHeight)
//                                else -> v.layout((screenWidth - btnHeight), top1.toInt(), screenWidth, bottom1.toInt())
//                            }
                            v.layout((screenWidth - btnWith), top1.toInt(), screenWidth, bottom1.toInt())
                        }
                    }
                }
                return false
            }
        })