Android sliding intercept instance code analysis

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/**
  * Created by huqing on 2016/12/7.
  * Idea:
  * Internal and external interception
  * In the parent layout, onInterceptTouchEvent first determines whether to intercept the slide, true intercepts the onTouch method that directly enters the parent layout; false enters the onTouch method that enters the child layout
  */
public class MyParentView extends LinearLayout
{
  /**
    * Distance per downward movement
    */
  private int mMove;
  /**
    * The position of the drop point
    */
  private int yDown;
  /**
    * The position of the moving point
    */
  private int yMove;
  /**
    * The total distance to move downward
    */
  private int downDistance = 0;
  public MyParentView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }
  boolean intercept = false;
  /**
    * External interception,
    * If it is sliding down, it is true, and it is handed over to the control for processing. If it is false upward, it is handed over to the subcontrol for processing.
    * So the upward events can be obtained by sub-controls
    *
    * @param ev
    * @return
    */
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev)
  {
    switch (())
    {
      case MotionEvent.ACTION_DOWN:
        yDown =(int) ();
        break;
      case MotionEvent.ACTION_MOVE:
        yMove = (int) ();
        if (yMove > yDown)
        {
          intercept = true;
          ("hqq", "Intercept~~~~~~~~~~~~~~~~~~~~~~~~~~");
        }
        else if (yMove < yDown)
        {
          intercept = false;
          ("hqq", "No intercepting~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
        }
        break;
      case MotionEvent.ACTION_UP:
        break;
    }
    //true intercept, enter the onTouchEvent method of the control false: enter the OnTouchEvent of the child control    boolean returnInterCept = intercept;
    intercept = false;
    return returnInterCept;
  }
  @Override
  public boolean onTouchEvent(MotionEvent event)
  {
    ("hq", "father onTouch");
    int y = (int) ();
    switch (())
    {
      case MotionEvent.ACTION_DOWN:
        yDown = y;
        break;
      case MotionEvent.ACTION_MOVE:
        if (downDistance>=250){
        }else {
          yMove = y;
          if (yMove - yDown > 0)
          {
            mMove = yMove - yDown;
            downDistance += mMove;
            if (downDistance>=250){
              layout(getLeft(),downDistance, getRight(), getHeight() + downDistance);
            }else {
              layout(getLeft(), getTop() + mMove, getRight(), getBottom() + mMove);
            }
          }
        }
        break;
      case MotionEvent.ACTION_UP:
        layout(getLeft(), getTop() - downDistance, getRight(), getBottom() - downDistance);
        downDistance = 0;
        break;
    }
    return true;//    return (event);
  }
}

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import ;
import ;
import ;
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import ;
/**
 * Created by huqing on 2016/12/7.
 */
public class MyScrollView extends ScrollView
{
  public MyScrollView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }
  @Override
  public boolean onTouchEvent(MotionEvent ev)
  {
    ("hq","child onTouch----------------");
    switch (()){
      case MotionEvent.ACTION_DOWN:
        getParent().requestDisallowInterceptTouchEvent(true);
        break;
      case MotionEvent.ACTION_MOVE:
        if (getScrollY()==0){//When the ScrollView is not sliding, that is, if the sliding height does not change, the parent control is allowed to intercept it.          getParent().requestDisallowInterceptTouchEvent(false);
        }else {//Offering is prohibited          getParent().requestDisallowInterceptTouchEvent(true);
        }
        break;
    }
    return (ev);
  }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  android:
  xmlns:andro
  xmlns:tools="/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@drawable/bg"
  tools:context="">
  <
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff"
    android:orientation="vertical">
    <TextView
      android:layout_width="wrap_content"
      android:layout_height="100dp"
      android:text=" World!"/>
    <TextView
      android:layout_width="wrap_content"
      android:layout_height="100dp"
      android:text=" World!"/>
    < android:layout_width="match_parent"
                   android:layout_height="wrap_content">
      <LinearLayout android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:orientation="vertical">
        <TextView
          android:layout_width="wrap_content"
          android:layout_height="200dp"
          android:text="Hello World!"/>
        <TextView
          android:layout_width="wrap_content"
          android:layout_height="200dp"
          android:text="Hello World!"/>
      </LinearLayout>
    </>
  </>
</RelativeLayout>