android应用内部悬浮可拖动按钮简单实现代码

WindowManager wm = (WindowManager) activity.getSystemService(Context.WINDOW_SERVICE);
    DisplayMetrics dm = new DisplayMetrics();
    activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
    //通过像素密度来设置按钮的大小
    dpi = dpi(dm.densityDpi);
    //屏宽
    screenWidth = wm.getDefaultDisplay().getWidth();
    //屏高
    screenHeight = wm.getDefaultDisplay().getHeight();
    //布局设置
    wmParams = new WindowManager.LayoutParams();
    // 设置window type
    wmParams.type = WindowManager.LayoutParams.TYPE_APPLICATION;
    wmParams.format = PixelFormat.RGBA_8888; // 设置图片格式，效果为背景透明
    wmParams.gravity = Gravity.LEFT | Gravity.TOP;
    // 设置Window flag
    wmParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
    wmParams.width = dpi;
    wmParams.height = dpi;
    wmParams.y = (screenHeight - dpi) >> 1;
    wm.addView(this, wmParams);

  /**
   * 根据密度选择控件大小
   *
   */
  private int dpi(int densityDpi) {
    if (densityDpi <= 120) {
      return 36;
    } else if (densityDpi <= 160) {
      return 48;
    } else if (densityDpi <= 240) {
      return 72;
    } else if (densityDpi <= 320) {
      return 96;
    }
    return 108;
  }

import android.app.Activity;
import android.content.Context;
import android.graphics.PixelFormat;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.RelativeLayout;
import android.widget.TextView;


/**
 * Created by xiang on 2016/12/28.
 *
 * im悬浮窗视图
 */

public class ChatView extends RelativeLayout{

  // 悬浮栏位置
  private final static int LEFT = 0;
  private final static int RIGHT = 1;
  private final static int TOP = 3;
  private final static int BUTTOM = 4;

  private int dpi;
  private int screenHeight;
  private int screenWidth;
  private WindowManager.LayoutParams wmParams;
  private WindowManager wm;
  private float x, y;
  private float mTouchStartX;
  private float mTouchStartY;
  private boolean isScroll;

  public ChatView(Activity activity) {
    super(activity);
    LayoutInflater.from(activity).inflate(R.layout.view_chat, this);
    setBackgroundResource(R.drawable.chat_btn);
    wm = (WindowManager) activity.getSystemService(Context.WINDOW_SERVICE);
    DisplayMetrics dm = new DisplayMetrics();
    activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
    //通过像素密度来设置按钮的大小
    dpi = dpi(dm.densityDpi);
    //屏宽
    screenWidth = wm.getDefaultDisplay().getWidth();
    //屏高
    screenHeight = wm.getDefaultDisplay().getHeight();
    //布局设置
    wmParams = new WindowManager.LayoutParams();
    // 设置window type
    wmParams.type = WindowManager.LayoutParams.TYPE_APPLICATION;
    wmParams.format = PixelFormat.RGBA_8888; // 设置图片格式，效果为背景透明
    wmParams.gravity = Gravity.LEFT | Gravity.TOP;
    // 设置Window flag
    wmParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
    wmParams.width = dpi;
    wmParams.height = dpi;
    wmParams.y = (screenHeight - dpi) >> 1;
    wm.addView(this, wmParams);
    hide();
  }


  /**
   * 根据密度选择控件大小
   *
   */
  private int dpi(int densityDpi) {
    if (densityDpi <= 120) {
      return 36;
    } else if (densityDpi <= 160) {
      return 48;
    } else if (densityDpi <= 240) {
      return 72;
    } else if (densityDpi <= 320) {
      return 96;
    }
    return 108;
  }

  public void show() {
    if (isShown()) {
      return;
    }
    setVisibility(View.VISIBLE);
  }


  public void hide() {
    setVisibility(View.GONE);
  }

  public void destory() {
    hide();
    wm.removeViewImmediate(this);
  }


  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // 获取相对屏幕的坐标， 以屏幕左上角为原点
    x = event.getRawX();
    y = event.getRawY();
    switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:
        // setBackgroundDrawable(openDrawable);
        // invalidate();
        // 获取相对View的坐标，即以此View左上角为原点
        mTouchStartX = event.getX();
        mTouchStartY = event.getY();
        break;
      case MotionEvent.ACTION_MOVE:
        if (isScroll) {
          updateViewPosition();
        } else {
          // 当前不处于连续滑动状态 则滑动小于图标1/3则不滑动
          if (Math.abs(mTouchStartX - event.getX()) > dpi / 3
              || Math.abs(mTouchStartY - event.getY()) > dpi / 3) {
            updateViewPosition();
          } else {
            break;
          }
        }
        isScroll = true;
        break;
      case MotionEvent.ACTION_UP:
        // 拖动
        if (isScroll) {
          autoView();
          // setBackgroundDrawable(closeDrawable);
          // invalidate();
        } else {
          // 当前显示功能区，则隐藏
          // setBackgroundDrawable(openDrawable);
          // invalidate();

        }
        isScroll = false;
        mTouchStartX = mTouchStartY = 0;
        break;
    }
    return true;
  }

  /**
   * 自动移动位置
   */
  private void autoView() {
    // 得到view在屏幕中的位置
    int[] location = new int[2];
    getLocationOnScreen(location);
    //左侧
    if (location[0] < screenWidth / 2 - getWidth() / 2) {
      updateViewPosition(LEFT);
    } else {
      updateViewPosition(RIGHT);
    }
  }

  /**
   * 手指释放更新悬浮窗位置
   *
   */
  private void updateViewPosition(int l) {
    switch (l) {
      case LEFT:
        wmParams.x = 0;
        break;
      case RIGHT:
        int x = screenWidth - dpi;
        wmParams.x = x;
        break;
      case TOP:
        wmParams.y = 0;
        break;
      case BUTTOM:
        wmParams.y = screenHeight - dpi;
        break;
    }
    wm.updateViewLayout(this, wmParams);
  }

  // 更新浮动窗口位置参数
  private void updateViewPosition() {
    wmParams.x = (int) (x - mTouchStartX);
    //是否存在状态栏（提升滑动效果）
    // 不设置为全屏（状态栏存在） 标题栏是屏幕的1/25
    wmParams.y = (int) (y - mTouchStartY - screenHeight / 25);
    wm.updateViewLayout(this, wmParams);
  }
}

//传入上下文Activity
ChatView chatView = new ChatView(this);
chatView.show();