记录贴1:可拖动,可吸附侧面的悬浮控件

主要功能项:
1. 可以拖动
2. 拖动完可以自动贴边
3. 可处理点击事件 
4. 可变化背景图(美术改图,弃之不用啊,可惜可惜)
   4.1 吸附左边的时候,背景为左边直角右边圆角的矩形
   4.2 吸附右边的时候,背景为右边直角左边圆角的矩形
   4.3 移动的时候,背景为圆角的矩形

第一步.上代码

class FloatView(context: Context, attributeSet: AttributeSet) :
    RelativeLayout(context, attributeSet) {

    private val MORE_SPACE = 10.0 //移动距离像素,超过才算移动
    private var mView: View? = null

    init {
        mView = LayoutInflater.from(context).inflate(R.layout.layout_float_view, this, true)

        val rotation = ObjectAnimator.ofFloat(mView?.iv_playing_bg, "rotation", 0f, 360f)
        rotation.duration = 15000
        rotation.repeatCount = -1
        rotation.start()
        val scaleX = ObjectAnimator.ofFloat(mView?.iv_playing_bg, "scaleX", 0.5f, 1f, 0.5f)
        scaleX.duration = 15000
        scaleX.repeatCount = -1
        scaleX.start()
        val scaleY = ObjectAnimator.ofFloat(mView?.iv_playing_bg, "scaleY", 0.5f, 1f, 0.5f)
        scaleY.duration = 15000
        scaleY.repeatCount = -1
        scaleY.start()
    }
    
    //控件的宽高
    private var mWidth = 0
    private var mHeight = 0
    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
        super.onSizeChanged(w, h, oldw, oldh)
        mWidth = w
        mHeight = h
    }

    //屏幕宽高以及半屏和上下边距
    private var mScreenWith = 0
    private var mScreenHeight = 0
    private var halfWith = 0
    private var mTop = 0
    private var mBottom = 0

    /**
     * 设置父布局的大小
     */
    fun setParentSize(width: Int, height: Int, top: Int, bottom: Int) {
        mScreenWith = width
        mScreenHeight = height
        halfWith = width / 2

        mTop = top
        mBottom = bottom
    }

    private var lastX = 0f //按下x
    private var lastY = 0f //按下y
    private var isMove = false //是拖动?
    private var isPress = false //是点击?
    private var offsetX = 0f  //偏移量x,移动的时候不加偏移量,按钮会发生位置错误,手指下会是按钮的左上角,而不是最初按下位置
    private var offsetY = 0f //偏移量y
    private var isChangeBg = false //吸边的时候可以更改变化按钮的左右两边圆角,后面美术改了个方图,不用了,但思路留在这

    override fun onTouchEvent(ev: MotionEvent): Boolean {
        val x = ev.rawX
        val y = ev.rawY
        when (ev.action) {
            MotionEvent.ACTION_DOWN -> {
                isMove = false
                isPress = true
                lastX = x
                lastY = y
                offsetX = getX() - x
                offsetY = getY() - y
            }
            MotionEvent.ACTION_MOVE -> {
                isMove = isMove(ev)
                isPress = if (isMove) {
                    if (!isChangeBg) {
                        isChangeBg = true
                        //思路:这里换背景图
                    }
                    val xandY = getXandY(x + offsetX, y + offsetY)
                    setX(xandY[0].toFloat())
                    setY(xandY[1].toFloat())
                    false
                } else {
                    true
                }
            }
            MotionEvent.ACTION_UP -> {
                isChangeBg = false
                if (isPress) {
                    callback?.click()
                    isPress = true
                }
                if (isMove) {
                    isMove = false
                }
                if (x != 0f || x != (mScreenWith - mWidth).toFloat()) {
                    if (x <= halfWith) {
                        //在左半边,吸附左边
                        if (x >lastX) {
                            animate().setInterpolator(DecelerateInterpolator())
                                .setDuration(500)
                                .xBy(-x - offsetX)
                                .start()
                                //思路:这里换背景图
                        }
                    } else {
                        //在右半边,吸附右边
                        if (x < laxtX) {
                            animate().setInterpolator(DecelerateInterpolator())
                                .setDuration(500)
                                .xBy(mScreenWith - mWidth - x - offsetX)
                                .start()
                               //思路:这里换背景图
                        }
                    }
                }
            }
        }
        return true
    }

    /**
     * 获取移动到的x和y
     */
    private fun getXandY(x: Float, y: Float): IntArray {
        val resultX = when {
            x < 0 -> {
                0
                 //思路:这里换背景图
            }
            x > mScreenWith - mWidth -> {
                mScreenWith - mWidth
                 //思路:这里换背景图
            }
            else -> {
                x.toInt()
            }
        }
        val resultY: Int = when {
            y < mTop -> {
                mTop
            }
            y > mScreenHeight - mBottom - mWidth -> {
                mScreenHeight - mBottom - mWidth
            }
            else -> {
                y.toInt()
            }
        }
        return intArrayOf(resultX, resultY)
    }


    private var callback: OnClickCallback? = null

    fun setOnClickCallback(callback: OnClickCallback) {
        this.callback = callback
    }

    interface OnClickCallback {
        fun click()
    }

    private fun isMove(ev: MotionEvent): Boolean {
        val x = ev.rawX
        val y = ev.rawY
        val moreSpace =
            Math.sqrt(((x - lastX) * (x - lastX) + (y - lastY) * (y - lastY)).toDouble())
        return moreSpace > MORE_SPACE
    }
}

第二步.上布局

第三步.使用

//设置可移动范围,正常是要贴边手机两侧,所以仅需要特别标注上下边距,毕竟不能滑动到状态栏和底部tab上去
floatView.setParentSize(手机宽,手机高,上边距,下边距)
//点击事件嘛,处理点击后的业务
floatView.setOnClickCallback(...)