Android运用onTouchEvent自定义滑动布局

/** 
 * Author：Biligle. 
 * 自定义布局 
 */ 
 
public class MyViewGroup extends ViewGroup { 
 
 private MyViewGroupListener listener;//接口，监听滑动事件 
 private int vertical = 0;//布局距离顶端距离（默认0） 
 
 public MyViewGroup(Context context) { 
  super(context); 
 } 
 
 public MyViewGroup(Context context, AttributeSet attrs) { 
  super(context, attrs); 
 } 
 
 public MyViewGroup(Context context, AttributeSet attrs, int defStyleAttr) { 
  super(context, attrs, defStyleAttr); 
 } 
 
 @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) 
 public MyViewGroup(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 
  super(context, attrs, defStyleAttr, defStyleRes); 
 } 
 
 
 private int downY = 0;//按下时的点 
 private int slide = 0;//最终移动距离 
 @Override 
 public boolean onTouchEvent(MotionEvent event) { 
  switch (event.getAction()){ 
   case MotionEvent.ACTION_DOWN: 
    downY = (int) event.getY(); 
    break; 
   case MotionEvent.ACTION_MOVE: 
    slide = downY - (int)event.getY(); 
    if(slide < 0){//下滑 
     vertical = listener.marginTop(Math.abs(slide)); 
    }else if(slide > 0){//上滑 
     vertical = listener.marginTop(-slide); 
    } 
    break; 
   case MotionEvent.ACTION_UP: 
    if(vertical < 300){ 
     //布局距离屏幕顶部小于300，就让布局充满整个屏幕 
     vertical = listener.marginTop(0); 
    } 
    break; 
  } 
  return true; 
 } 
 
 /** 
  * 测量子View 
  * @param widthMeasureSpec 
  * @param heightMeasureSpec 
  */ 
 @Override 
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
  super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
  for (int i = 0; i < getChildCount(); i++) { 
   View child = getChildAt(i); 
   //系统测量 
   measureChild(child, widthMeasureSpec, heightMeasureSpec); 
  } 
 } 
 
 /** 
  * 安排子View的位置 
  * @param changed 
  * @param l 左边距 
  * @param t 上边距 
  * @param r 右边距 
  * @param b 下边距 
  */ 
 @Override 
 protected void onLayout(boolean changed, int l, int t, int r, int b) { 
  int left = 0, top = 0, right = 0, bottom = 0; 
  for (int i = 0; i < getChildCount(); i++) { 
   View child = getChildAt(i); 
   right = left + child.getMeasuredWidth(); 
   bottom = top + child.getMeasuredHeight(); 
   child.layout(left, top, right, bottom); 
  } 
 } 
 
 public void setListener(MyViewGroupListener listener){ 
  this.listener = listener; 
 } 
 
 interface MyViewGroupListener { 
  /** 
   * 设置topMargin，上下滑动时触发 
   * @param slide 滑动距离 
   * @return 当前上边距 
   */ 
  int marginTop(int slide); 
 } 
}

public class MainActivity extends AppCompatActivity implements MyViewGroup.MyViewGroupListener{ 
 
 /** 自定义布局（外层布局）*/ 
 private MyViewGroup myViewGroup; 
 /** 两个圆形图（在外层布局）*/ 
 private ImageView iv1,iv2/*,cloud*/; 
 /** 包裹圆形图的布局*/ 
 private RelativeLayout relativeLayout; 
 /** 外层布局参数类（这里用到了params.topMargin：上边距）*/ 
 private ViewGroup.MarginLayoutParams params; 
 /** 透明值（改变两个圆图的透明值）*/ 
 private float f; 
 /** 左右内边距（改变RelativeLayout内边距）*/ 
 private int p; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  myViewGroup = (MyViewGroup) findViewById(R.id.my); 
  myViewGroup.setListener(this); 
  iv1 = (ImageView) findViewById(R.id.iv1); 
  iv2 = (ImageView) findViewById(R.id.iv2); 
  relativeLayout = (RelativeLayout) findViewById(R.id.relative); 
  params = (ViewGroup.MarginLayoutParams) myViewGroup.getLayoutParams(); 
  //初始化动画（自动下滑一段儿距离），我这里写死了900 
  ObjectAnimator animator = ObjectAnimator.ofFloat(myViewGroup,"translationY", 900); 
  animator.setDuration(2000); 
  animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { 
   @Override 
   public void onAnimationUpdate(ValueAnimator animation) { 
    float y = (float)animation.getAnimatedValue(); 
    f = y/800; 
    p = (int) y/3; 
    alpha(f); 
    padding(p); 
   } 
  }); 
  animator.start(); 
//  cloud = (ImageView) findViewById(R.id.cloud); 
 } 
 
 
 /** 
  * 设置上边距 
  * @param slide 滑动距离 
  * @return 返回下滑布局，距离屏幕左上角的垂直距离 
  */ 
 @Override 
 public int marginTop(int slide) { 
  params.topMargin += slide; 
  myViewGroup.setLayoutParams(params); 
  int vertical = (900 + params.topMargin); 
  if(slide == 0){ 
   //为了隐藏两张圆图，所以把Relativelayout的高度一并减除。 
   params.topMargin -= (vertical+relativeLayout.getHeight()); 
   myViewGroup.setLayoutParams(params); 
  } 
  float alpha = f + (float) params.topMargin/800;//自定义一个算法 
  alpha(alpha); 
  int padding = p + params.topMargin/3;//自定义一个算法 
  padding(padding); 
  return vertical; 
 } 
 
 /** 
  * 设置透明度 
  * @param alpha 透明值 
  */ 
 public void alpha(float alpha) { 
  iv1.setAlpha(alpha); 
  iv2.setAlpha(alpha); 
 } 
 
 /** 
  * 设置左右边距 
  * @param padding 边距值 
  */ 
 public void padding(int padding) { 
  relativeLayout.setPadding(padding, 0, padding, 0); 
 } 

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout 
 xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:app="http://schemas.android.com/apk/res-auto" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:id="@+id/activity_main" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 tools:context="com.wgl.viewgroup1.MainActivity"> 
 <ImageView 
  android:id="@+id/iv" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:src="@mipmap/pic" 
  android:scaleType="fitXY"/> 
  <!--<ImageView--> 
   <!--android:id="@+id/cloud"--> 
   <!--android:layout_width="wrap_content"--> 
   <!--android:layout_height="wrap_content"--> 
   <!--android:layout_centerHorizontal="true"--> 
   <!--android:alpha="0.8"--> 
   <!--android:src="@mipmap/cloud3"--> 
   <!--android:clickable="true"/>--> 
 
 <com.wgl.viewgroup1.MyViewGroup 
  android:id="@+id/my" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:alpha="0.8" 
  android:layout_alignParentTop="true"> 
  <LinearLayout 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical"> 
   <RelativeLayout 
    android:id="@+id/relative" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:orientation="horizontal"> 
    <com.wgl.viewgroup1.CircleImageView 
     android:id="@+id/iv1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:src="@mipmap/iv1" 
     app:civ_border_width="2dp" 
     app:civ_border_color="@color/colorAccent" 
     android:layout_alignParentLeft="true"/> 
 
    <com.wgl.viewgroup1.CircleImageView 
     android:id="@+id/iv2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:src="@mipmap/iv2" 
     app:civ_border_width="2dp" 
     app:civ_border_color="@color/colorAccent" 
     android:layout_alignParentRight="true"/> 
   </RelativeLayout> 
   <LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:alpha="0.8" 
    android:background="@color/colorPrimary"> 
 
   </LinearLayout> 
  </LinearLayout> 
 
 </com.wgl.viewgroup1.MyViewGroup> 
</RelativeLayout>