Android实现单页面浮层可拖动view的一种方法

import android.content.Context;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatImageView;
import android.util.AttributeSet;
import android.view.MotionEvent;

/**
 * Created by hq on 2017/10/10.
 * 参考：http://blog.csdn.net/zane_xiao/article/details/51188867
 */

public class DragImageView extends AppCompatImageView {
  String TAG = "DragImageView";

  public DragImageView(Context context) {
    this(context, null);
  }

  public DragImageView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public DragImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
  }

  /**
   * 设置在父布局中的边界
   * @param l
   * @param t
   * @param r
   * @param b
   */
  public void initEdge(int l,int t,int r,int b) {
    edgeLeft = l;
    edgeTop = t;
    edgeRight = r;
    edgeBottom = b;
  }

  int edgeLeft, edgeTop, edgeRight, edgeBottom;
  int lastX, lastY, movex, movey, dx, dy;

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:
        lastX = (int) event.getRawX();
        lastY = (int) event.getRawY();
        movex = lastX;
        movey = lastY;
        break;
      case MotionEvent.ACTION_MOVE:
        dx = (int) event.getRawX() - lastX;
        dy = (int) event.getRawY() - lastY;

        int left = getLeft() + dx;
        int top = getTop() + dy;
        int right = getRight() + dx;
        int bottom = getBottom() + dy;
        if (left < edgeLeft) {
          left = edgeLeft;
          right = left + getWidth();
        }
        if (right > edgeRight) {
          right = edgeRight;
          left = right - getWidth();
        }
        if (top < edgeTop) {
          top = edgeTop;
          bottom = top + getHeight();
        }
        if (bottom > edgeBottom) {

          bottom = edgeBottom;
          top = bottom - getHeight();
        }

        layout(left, top, right, bottom);
        lastX = (int) event.getRawX();
        lastY = (int) event.getRawY();
        break;
      case MotionEvent.ACTION_UP:
        //避免滑出触发点击事件
        if ((int) (event.getRawX() - movex) != 0
          || (int) (event.getRawY() - movey) != 0) {
          return true;
        }
        break;
      default:
        break;
    }
    return super.onTouchEvent(event);
  }
}

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/df_content"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.windfindtech.ishanghai.view.SwipeScrollView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@color/default_white"
  android:scrollbars="none">

  <RelativeLayout
    android:id="@+id/network_tab_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/default_white">

    ...........

  </RelativeLayout>
</com.windfindtech.ishanghai.view.SwipeScrollView>

<com.windfindtech.ishanghai.view.DragImageView
  android:id="@+id/iv_drag_adver"
  android:layout_width="40dp"
  android:layout_height="40dp"
  android:layout_gravity="right|top"
  android:src="@drawable/ic_launcher" />
</FrameLayout>