Android滑动拦截实例代码解析

 package demo.hq.com.fby;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.LinearLayout;
/**
 * Created by huqing on 2016/12/7.
 * 思路：
 * 分内外部拦截
 * 在父布局中，onInterceptTouchEvent先判断是否拦截滑动，true 拦截 直接进入父布局的onTouch方法 ；false 进入子布局的onTouch方法
 */
public class MyParentView extends LinearLayout
{
  /**
   * 每向下Move移动的距离
   */
  private int mMove;
  /**
   * 落下点的位置
   */
  private int yDown;
  /**
   * 移动点的位置
   */
  private int yMove;
  /**
   * 一共向下挪动的距离
   */
  private int downDistance = 0;
  public MyParentView(Context context, AttributeSet attrs)
  {
    super(context, attrs);
  }
  boolean intercept = false;
  /**
   * 外部拦截，
   * 如果是向下滑动 则为true,交给该控件处理，向上false就交给子控件处理吧
   * 所以向上的事件 子控件都能获取到的
   *
   * @param ev
   * @return
   */
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev)
  {
    switch (ev.getAction())
    {
      case MotionEvent.ACTION_DOWN:
        yDown =(int) ev.getY();
        break;
      case MotionEvent.ACTION_MOVE:
        yMove = (int) ev.getY();
        if (yMove > yDown)
        {
          intercept = true;
          Log.d("hqq", "拦截~~~~~~~~~~~~~~~~~~");
        }
        else if (yMove =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 super.onTouchEvent(event);
  }
}

package demo.hq.com.fby;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.ScrollView;
/**
 * 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)
  {
    Log.e("hq","child onTouch----------------");
    switch (ev.getAction()){
      case MotionEvent.ACTION_DOWN:
        getParent().requestDisallowInterceptTouchEvent(true);
        break;
      case MotionEvent.ACTION_MOVE:
        if (getScrollY()==0){//ScrollView没有滑动时 ，即滑动高度没变化的话就允许父控件拦截
          getParent().requestDisallowInterceptTouchEvent(false);
        }else {//禁止拦截
          getParent().requestDisallowInterceptTouchEvent(true);
        }
        break;
    }
    return super.onTouchEvent(ev);
  }
}

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