Android自定义可拖拽的悬浮按钮DragFloatingActionButton

悬浮按钮FloatingActionButton是Android 5.0系统添加的新控件,FloatingActionButton是继承至ImageView，所以FloatingActionButton拥有ImageView的所有属性。本文讲解的是一个实现了可拖拽的悬浮按钮，并为此添加了类似于qq的吸附边框的功能。在此之前，先了解下其简单的使用方式吧：

首先你得添加其依赖

compile 'com.android.support:design:25.3.1'

然后在布局文件中使用。

<android.support.design.widget.FloatingActionButton
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_gravity="right|bottom"
   android:src="@drawable/ic_launcher"
   />

如图：

FloatingActionButton正常显示的情况下有个填充的颜色，有个阴影；点击的时候会有一个rippleColor，并且阴影的范围可以增大。其中：

1、填充的颜色默认使用就是style当中的colorAccent。

2、rippleColor默认取的是Theme当中的colorControlHighlight。

3、elevation和pressedTranslationZ，前者用户设置正常显示的阴影大小；后者是点击时显示的阴影大小。

好了，现在介绍本文的重点：可拖拽的，有吸附功能的悬浮按钮

先上代码。

import android.animation.ObjectAnimator;
import android.content.Context;
import android.support.design.widget.FloatingActionButton;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.animation.DecelerateInterpolator;
public class DragFloatActionButton extends FloatingActionButton {
 private int screenWidth;
 private int screenHeight;
 private int screenWidthHalf;
 private int statusHeight;
 private int virtualHeight;
 public DragFloatActionButton(Context context) {
  super(context);
  init();
 }
 public DragFloatActionButton(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }
 public DragFloatActionButton(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init();
 }
 private void init() {
  screenWidth = ScreenUtils.getScreenWidth(getContext());
  screenWidthHalf = screenWidth / 2;
  screenHeight = ScreenUtils.getScreenHeight(getContext());
  statusHeight = ScreenUtils.getStatusHeight(getContext());
  virtualHeight=ScreenUtils.getVirtualBarHeigh(getContext());
 }
 private int lastX;
 private int lastY;
 private boolean isDrag;
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  int rawX = (int) event.getRawX();
  int rawY = (int) event.getRawY();
  switch (event.getAction() & MotionEvent.ACTION_MASK) {
   case MotionEvent.ACTION_DOWN:
    isDrag = false;
    getParent().requestDisallowInterceptTouchEvent(true);
    lastX = rawX;
    lastY = rawY;
    Log.e("down---->", "getX=" + getX() + "；screenWidthHalf=" + screenWidthHalf);
    break;
   case MotionEvent.ACTION_MOVE:
    isDrag = true;
    //计算手指移动了多少
    int dx = rawX - lastX;
    int dy = rawY - lastY;
    //这里修复一些手机无法触发点击事件的问题
    int distance= (int) Math.sqrt(dx*dx+dy*dy);
    Log.e("distance---->",distance+"");
    if(distance<3){//给个容错范围，不然有部分手机还是无法点击
     isDrag=false;
     break;
    }
    float x = getX() + dx;
    float y = getY() + dy;
    //检测是否到达边缘 左上右下
    x = x < 0 ? 0 : x > screenWidth - getWidth() ? screenWidth - getWidth() : x;
    // y = y < statusHeight ? statusHeight : (y + getHeight() >= screenHeight ? screenHeight - getHeight() : y);
    if (y<0){
     y=0;
    }
    if (y>screenHeight-statusHeight-getHeight()){
     y=screenHeight-statusHeight-getHeight();
    }
    setX(x);
    setY(y);
    lastX = rawX;
    lastY = rawY;
    Log.e("move---->", "getX=" + getX() + "；screenWidthHalf=" + screenWidthHalf + " " + isDrag+" statusHeight="+statusHeight+ " virtualHeight"+virtualHeight+ " screenHeight"+ screenHeight+" getHeight="+getHeight()+" y"+y);
    break;
   case MotionEvent.ACTION_UP:
    if (isDrag) {
     //恢复按压效果
     setPressed(false);
     Log.e("ACTION_UP---->", "getX=" + getX() + "；screenWidthHalf=" + screenWidthHalf);
     if (rawX >= screenWidthHalf) {
      animate().setInterpolator(new DecelerateInterpolator())
        .setDuration(500)
        .xBy(screenWidth - getWidth() - getX())
        .start();
     } else {
      ObjectAnimator oa = ObjectAnimator.ofFloat(this, "x", getX(), 0);
      oa.setInterpolator(new DecelerateInterpolator());
      oa.setDuration(500);
      oa.start();
     }
    }
    Log.e("up---->",isDrag+"");
    break;
  }
  //如果是拖拽则消耗事件，否则正常传递即可。
  return isDrag || super.onTouchEvent(event);
 }
}

ScreenUtils.Java

package com.example.cmos.retrofitdemo;
import android.app.Activity;
import android.content.Context;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.Window;
import android.view.WindowManager;
import java.lang.reflect.Method;
/**
 * Created by gongwq on 2017/6/14 0014.
 */
public class ScreenUtils {
 private ScreenUtils() {
  /* cannot be instantiated */
  throw new UnsupportedOperationException("cannot be instantiated");
 }
 /**
  * 获得屏幕高度
  *
  * @param context
  * @return
  */
 public static int getScreenWidth(Context context) {
  WindowManager wm = (WindowManager) context
    .getSystemService(Context.WINDOW_SERVICE);
  DisplayMetrics outMetrics = new DisplayMetrics();
  wm.getDefaultDisplay().getMetrics(outMetrics);
  return outMetrics.widthPixels;
 }
 /**
  * 获得屏幕宽度
  *
  * @param context
  * @return
  */
 public static int getScreenHeight(Context context) {
  WindowManager wm = (WindowManager) context
    .getSystemService(Context.WINDOW_SERVICE);
  DisplayMetrics outMetrics = new DisplayMetrics();
  wm.getDefaultDisplay().getMetrics(outMetrics);
  return outMetrics.heightPixels;
 }
 /**
  * 获得状态栏的高度
  *
  * @param context
  * @return
  */
 public static int getStatusHeight(Context context) {
  int statusHeight = -1;
  try {
   Class<?> clazz = Class.forName("com.android.internal.R$dimen");
   Object object = clazz.newInstance();
   int height = Integer.parseInt(clazz.getField("status_bar_height")
     .get(object).toString());
   statusHeight = context.getResources().getDimensionPixelSize(height);
  } catch (Exception e) {
   e.printStackTrace();
  }
  return statusHeight;
 }
 /**
  * 获取虚拟功能键高度
  */
 public static int getVirtualBarHeigh(Context context) {
  int vh = 0;
  WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
  Display display = windowManager.getDefaultDisplay();
  DisplayMetrics dm = new DisplayMetrics();
  try {
   @SuppressWarnings("rawtypes")
   Class c = Class.forName("android.view.Display");
   @SuppressWarnings("unchecked")
   Method method = c.getMethod("getRealMetrics", DisplayMetrics.class);
   method.invoke(display, dm);
   vh = dm.heightPixels - windowManager.getDefaultDisplay().getHeight();
  } catch (Exception e) {
   e.printStackTrace();
  }
  return vh;
 }
 public static int getVirtualBarHeigh(Activity activity) {
  int titleHeight = 0;
  Rect frame = new Rect();
  activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
  int statusHeight = frame.top;
  titleHeight = activity.getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop() - statusHeight;
  return titleHeight;
 }
}

上面的代码也很简单，相信看代码中的注释就可以看的明白了。但是这里还是讲下其实现原理：这个自定义的悬浮按钮，我们主要是重写了其onTouch事件，捕捉触摸事件，然后利用setX(),setY()方法将其移动。而吸附效果，主要是利用的属性动画，最后，不要忘了return 是否还在拖拽的结果，免得无法触发点击事件。

PS

最后贴一个弹出框。推荐用popmenu,相比于popwindow，这个会自动调整显示的位置，这在拖拽的悬浮按钮中很有用，因为如果用后者，你将按钮移到屏幕上方，而当你的弹出框也是设置在显示的悬浮按钮的上方，那么就有可能会遮挡弹出框的内容。

dragFloatActionButton= (DragFloatActionButton) findViewById(R.id.floatBtn);
  dragFloatActionButton.setOnClickListener(this);
....
 @Override
 public void onClick(View view) {
  switch (view.getId()) {
   case R.id.floatBtn:
    PopupMenu popupMenu=new PopupMenu(this,view);
    getMenuInflater().inflate(R.menu.pop_item,popupMenu.getMenu());
    popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
     @Override
     public boolean onMenuItemClick(MenuItem menuItem) {
      switch (menuItem.getItemId()){
       case R.id.action_last:
        Toast.makeText(TestActivity.this,""+menuItem.getItemId(),Toast.LENGTH_SHORT).show();
        break;
       case R.id.action_next:
        Toast.makeText(TestActivity.this,""+menuItem.getItemId(),Toast.LENGTH_SHORT).show();
        break;
      }
      return false;
     }
    });
    popupMenu.show();
    Log.e("****--->","float");
    // Toast.makeText(this,"flaot---",Toast.LENGTH_SHORT).show();
    break;
  }
 }

新建menu文件夹，在里面添加pop_item.xml文件

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto">
 <item
  android:id="@+id/action_delete"
  android:orderInCategory="100"
  android:title="删除"
  app:showAsAction="never" />
 <item
  android:id="@+id/action_save"
  android:orderInCategory="200"
  android:title="保存"
  app:showAsAction="never" />
 <item
  android:id="@+id/action_last"
  android:orderInCategory="300"
  android:title="上一步"
  app:showAsAction="never" />
 <item
  android:id="@+id/action_next"
  android:icon="@null"
  android:orderInCategory="400"
  android:title="下一步"
  app:showAsAction="never" />
</menu>

以上所述是小编给大家介绍的Android自定义可拖拽的悬浮按钮DragFloatingActionButton，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！