Android中实现一个可拖动的悬浮按钮，点击弹出菜单的功能

如图：

         

实现思路
通过重写控件的onTouchEvent方法监听触摸效果
通过View的setX()和setY()方法实现移动
使用属性动画实现边缘吸附效果
手指按下
首先是处理手指按压下的事件，这里我们把拖拽标识符设置为false并记录当前点击的屏幕坐标。然后我们在移动事件处

手指移动
这里我们把拖拽标识符设置为true，因为手指移动了。然后我们需要计算手指移动了多少偏移量

//计算手指移动了多少
int dx=rawX-lastX;
int dy=rawY-lastY;

而后的两行代码表示控件需要移动的具体距离，后面有一个简单的边缘检测计算。最终通过调用setX以及setY方法实现控件的移动

手指松开
这里如果是拖拽动作我们才需要处理自己的逻辑否则直接跳过即可。在这里我们首先恢复了按钮的按压效果，在源代码中找到setPressed(boolean)方法，这是处理按钮点击效果用的，在这里当手指松开后我们需要恢复按钮原来的效果。然后在判断控件需要往哪边吸附，吸附的过程就是做属性动画而已，原理还是不断的改变setX方法让按钮靠边移动

代码区
关于自定义的拖拽View (核心部分)
继承类(均可实现拖拽)

有的继承AppCompatImageView下的ImageView
有的继承FloatingActionButton(如果继承此类需要导入以下依赖)

compile 'com.android.support:design:26.1.0'
implementation 'com.android.support:appcompat-v7:26.1.0'

DragFloatActionButton （Kotlin版）

package com.example.mychartdemo

import android.animation.ObjectAnimator
import android.annotation.SuppressLint
import android.content.Context
import android.util.AttributeSet
import android.util.Log
import android.view.MotionEvent
import android.view.ViewGroup
import android.view.animation.DecelerateInterpolator
import android.widget.ImageView
//https://blog.csdn.net/qq_20451879/article/details/87876673
//效果可以
@SuppressLint("AppCompatCustomView")
class DragFloatActionButton : ImageView {
    private var parentHeight: Int = 0
    private var parentWidth: Int = 0

    constructor(context: Context?) : super(context)
    constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)

    private var lastX: Int = 0
    private var lastY: Int = 0

    public var isDrag: Boolean = false
    public var isRight: Boolean = false
    public var isTop: Boolean = true
    public var isCanMove: Boolean = true

    override fun onTouchEvent(event: MotionEvent): Boolean {
        val rawX = event.rawX.toInt()
        val rawY = event.rawY.toInt()
        Log.i("打印X轴、Y轴坐标：","rawX：$rawX  ,rawY: $rawY")
         if (!isCanMove){//不可移动
             return super.onTouchEvent(event)
         }

        when (event.action and MotionEvent.ACTION_MASK) {
            MotionEvent.ACTION_DOWN -> {
                isPressed = true
                isDrag = false
                parent.requestDisallowInterceptTouchEvent(true)
                lastX = rawX
                lastY = rawY
                val parent: ViewGroup
                if (getParent() != null) {
                    parent = getParent() as ViewGroup
                    parentHeight = parent.height
                    parentWidth = parent.width
                }
            }
            MotionEvent.ACTION_MOVE -> {
                isDrag = !(parentHeight <= 0 || parentWidth === 0)
                /*if (parentHeight <= 0 || parentWidth === 0) {
                    isDrag = false
                } else {
                    isDrag = true
                }*/
                val dx = rawX - lastX
                val dy = rawY - lastY
                //这里修复一些华为手机无法触发点击事件
                val distance = Math.sqrt((dx * dx + dy * dy).toDouble()).toInt()
                if (distance == 0) {
                    isDrag = false
                } else {
                    var x = x + dx
                    var y = y + dy
                    //检测是否到达边缘 左上右下
                    x = if (x < 0) 0F else if (x > parentWidth - width) (parentWidth - width).toFloat() else x
                    y = if (getY() < 0) 0F else if (getY() + height > parentHeight) (parentHeight - height).toFloat() else y
                    setX(x)
                    setY(y)
                    lastX = rawX
                    lastY = rawY
                    Log.i("aa", "isDrag=" + isDrag + "getX=" + getX() + ";getY=" + getY() + ";parentWidth=" + parentWidth)
                }
            }
            MotionEvent.ACTION_UP -> if (!isNotDrag()) {
                //恢复按压效果
                isPressed = false
                //Log.i("getX="+getX()+"；screenWidthHalf="+screenWidthHalf);
                if (rawX >= parentWidth / 2) {
                    //靠右吸附
                    animate().setInterpolator(DecelerateInterpolator())
                        .setDuration(500)
                        .xBy(parentWidth - width - x)
                        .start()

                    isRight = true
                } else {
                    //靠左吸附
                    val oa = ObjectAnimator.ofFloat(this, "x", x, 0F)
                    oa.interpolator = DecelerateInterpolator()
                    oa.duration = 500
                    oa.start()

                    isRight = false
                }
                //判断是否位于上半部分
                isTop = rawY <= parentHeight/2
                Log.i("打印是否位于顶部：",""+isTop)
            }
        }
        //如果是拖拽则消s耗事件，否则正常传递即可。
        return !isNotDrag() || super.onTouchEvent(event)
    }

    private fun isNotDrag(): Boolean {
        return !isDrag && (x == 0f || x == (parentWidth - width).toFloat())
    }
}

　　主布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity3">
    <com.example.mychartdemo.DragFloatActionButton
        android:layout_width="45dp"
        android:layout_height="45dp"
        android:id="@+id/img_btn"
        android:src="@mipmap/ic_launcher"></com.example.mychartdemo.DragFloatActionButton>


</LinearLayout>

　MainActivity

package com.example.mychartdemo

import android.graphics.drawable.BitmapDrawable
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.ImageView
import android.widget.PopupWindow
import android.widget.RadioGroup
import androidx.appcompat.app.AppCompatActivity
import com.example.mychartdemo.databinding.ActivityMain3Binding

class MainActivity : AppCompatActivity(),View.OnClickListener{

    private  var popupWindow: PopupWindow? = null

    private lateinit var binding: ActivityMain3Binding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMain3Binding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.imgBtn.setOnClickListener {
         
            if (popupWindow == null) {
                initPopWindow()
                //设置不可拖动
                binding.imgBtn.isCanMove = false
            } else if (popupWindow != null && popupWindow?.isShowing == true) {
                popupWindow?.dismiss()
                popupWindow = null
                //设置可拖动
                binding.imgBtn.isCanMove = true
                
            }

        }


    }

    private fun initPopWindow() {
        var view: View? = null
        if(binding.imgBtn.isRight){
           view = View.inflate(this, R.layout.popwindow_view, null)
        }else{
            view = View.inflate(this, R.layout.popwindow_left_view, null)
        }

        val popimg_1: ImageView = view.findViewById<ImageView>(R.id.popimg_1)
        popimg_1.setOnClickListener(this)
        val popimg_2: ImageView = view.findViewById<ImageView>(R.id.popimg_2)
        popimg_2.setOnClickListener(this)
        val popimg_3: ImageView = view.findViewById<ImageView>(R.id.popimg_3)
        popimg_3.setOnClickListener(this)
        popupWindow = PopupWindow(
            view,
            DensityUtil.dip2px(this, 160F),
            RadioGroup.LayoutParams.WRAP_CONTENT
        )
        popupWindow?.setTouchable(true) //设置可以点击
        popupWindow?.setOutsideTouchable(false) //点击外部关闭

        // popupWindow.setBackgroundDrawable(new ColorDrawable());//设置背景
        // popupWindow.setBackgroundDrawable(new ColorDrawable());//设置背景
        popupWindow?.setBackgroundDrawable(BitmapDrawable())
        if (binding.imgBtn.isTop){
            Log.i("打印是否位于顶部111：",""+binding.imgBtn.isTop)
            popupWindow?.showAsDropDown(binding.imgBtn)
        }else{
            if(binding.imgBtn.isRight){
                Log.i("打印是否位于顶部222：",""+binding.imgBtn.isTop)
                popupWindow?.showAsDropDown(binding.imgBtn)
            }else{
                Log.i("打印是否位于顶部3333：",""+binding.imgBtn.isTop)
                popupWindow?.showAsDropDown(binding.imgBtn,0,DensityUtil.dip2px(this,-200F))
            }


        }


    }

    override fun onClick(v: View) {
        when (v.id) {
            R.id.popimg_1 -> {
                if (popupWindow != null) {
                    popupWindow?.dismiss()
                    popupWindow = null
                    //设置可拖动
                    binding.imgBtn.isCanMove = true
                  Log.i("点击了","111")
                }else{
                    Log.i("点击了","2222")
                }

            }
            R.id.popimg_2 -> {
                if (popupWindow != null) {
                    popupWindow?.dismiss()
                    popupWindow = null
                    //设置可拖动
                    binding.imgBtn.isCanMove = true
                }
            }
            R.id.popimg_3 -> {
                if (popupWindow != null) {
                    popupWindow?.dismiss()
                    popupWindow = null
                    //设置可拖动
                    binding.imgBtn.isCanMove = true
                }
            }
        }
    }
}

popwindow_view 布局文件

　　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="满刻度"
            android:gravity="center|right"
            android:paddingRight="10dp"></TextView>
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_1"></ImageView>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="数据明细"
            android:gravity="center|right"
            android:paddingRight="10dp"></TextView>
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_2"></ImageView>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="选择日期"
            android:gravity="center|right"
            android:paddingRight="10dp"></TextView>
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_3"></ImageView>
    </LinearLayout>

</LinearLayout>

　　popwindow_left_view  左边布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">

        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_1"></ImageView>
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="满刻度"
            android:gravity="center|left"
            android:paddingLeft="10dp"></TextView>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_2"></ImageView>
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="数据明细"
            android:gravity="center|left"
            android:paddingLeft="10dp"></TextView>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:orientation="horizontal">
        <ImageView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:src="@mipmap/ic_launcher"
            android:id="@+id/popimg_3"></ImageView>
        <TextView
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="选择日期"
            android:gravity="center|left"
            android:paddingLeft="10dp"></TextView>
    </LinearLayout>

</LinearLayout>

　　完成

参考于：https://blog.csdn.net/qq_20451879/article/details/87876673