Android中ScrollView 滑到头部或尾部可伸缩放大效果

package com.kokjuis.travel.customView; import android.animation.ObjectAnimator; import android.animation.ValueAnimator; import android.content.Context; import android.graphics.Rect; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.TranslateAnimation; import android.widget.ScrollView; /**  * 注意使用的时候需要放大的view,一般是第一个RelativeLayout或者LinearLayout。要加上 android:layout_gravity="center_horizontal"  * <p>  * Created by kokJuis on 2017/3/14. 189155278@qq.com  */ public class BounceZoomScrollView extends ScrollView {  private static final String TAG = "BounceScrollView";  //----头部收缩属性--------  // 记录首次按下位置  private float mFirstPosition = 0;  // 头部图片是否正在放大  private Boolean mScaling = false;  private View dropZoomView;//需要被放大的view  private int dropZoomViewWidth;  private int dropZoomViewHeight;  //----头部收缩属性end--------  //------尾部收缩属性--------  private View inner;// 子View  private float y;// 点击时y坐标  private Rect normal = new Rect();// 矩形(这里只是个形式，只是用于判断是否需要动画.)  private boolean isCount = false;// 是否开始计算  //最后的坐标  private float lastX = 0;  private float lastY = 0;  //当前坐标  private float currentX = 0;  private float currentY = 0;  //移动的坐标量  private float distanceX = 0;  private float distanceY = 0;  private boolean upDownSlide = false; //判断上下滑动的flag  //------尾部收缩属性end--------  public BounceScrollView(Context context, AttributeSet attrs) {  super(context, attrs);  }  //初始化  private void init() {  setOverScrollMode(OVER_SCROLL_NEVER);  if (getChildAt(0) != null) {   inner = getChildAt(0);//这个是底部收缩的view   //头部收缩的   ViewGroup vg = (ViewGroup) getChildAt(0);   if (vg.getChildAt(0) != null) {   dropZoomView = vg.getChildAt(0);   }  }  }  /***  * 生成视图工作完成.该函数在生成视图的最后调用，在所有子视图添加完之后. 即使子类覆盖了 onFinishInflate  * 方法，也应该调用父类的方法，使该方法得以执行.  */  @Override  protected void onFinishInflate() {  //初始化  init();  super.onFinishInflate();  }  @Override  public boolean dispatchTouchEvent(MotionEvent ev) {  //这里只是计算尾部坐标  currentX = ev.getX();  currentY = ev.getY();  switch (ev.getAction()) {   case MotionEvent.ACTION_MOVE:   distanceX = currentX - lastX;   distanceY = currentY - lastY;   if (Math.abs(distanceX) < Math.abs(distanceY) && Math.abs(distanceY) > 12) {    upDownSlide = true;   }   break;  }  lastX = currentX;  lastY = currentY;  if (upDownSlide && inner != null) commOnTouchEvent(ev);  return super.dispatchTouchEvent(ev);  }  /***  * 触摸事件  *  * @param ev  */  public void commOnTouchEvent(MotionEvent ev) {  //头部缩放计算  if (dropZoomViewWidth <= 0 || dropZoomViewHeight <= 0) {   dropZoomViewWidth = dropZoomView.getMeasuredWidth();   dropZoomViewHeight = dropZoomView.getMeasuredHeight();  }  switch (ev.getAction()) {   case MotionEvent.ACTION_UP:   //手指离开后头部恢复图片   mScaling = false;   replyImage();   // 手指松开尾部恢复   if (isNeedAnimation()) {    animation();    isCount = false;   }   clear0();   break;   //这里头尾分开处理，互不干扰   case MotionEvent.ACTION_MOVE:   //尾部处理   final float preY = y;// 按下时的y坐标   float nowY = ev.getY();// 时时y坐标   int deltaY = (int) (preY - nowY);// 滑动距离   if (!isCount) {    deltaY = 0; // 在这里要归0.   }   y = nowY;   // 当滚动到最上或者最下时就不会再滚动，这时移动布局   if (isNeedMove()) {    // 初始化头部矩形    if (normal.isEmpty()) {    // 保存正常的布局位置    normal.set(inner.getLeft(), inner.getTop(),     inner.getRight(), inner.getBottom());    }    // 移动布局    inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,     inner.getRight(), inner.getBottom() - deltaY / 2);   }   isCount = true;   //尾部处理end   //头部处理   if (!mScaling) {    if (getScrollY() == 0) {    mFirstPosition = ev.getY();// 滚动到顶部时记录位置，否则正常返回    } else {    break;    }   }   int distance = (int) ((ev.getY() - mFirstPosition) * 0.6); // 滚动距离乘以一个系数   if (distance < 0) { // 当前位置比记录位置要小，正常返回    break;   }   // 处理放大   mScaling = true;   setZoom(1 + distance);   //头部处理end   break;  }  }  /***  * 回缩动画,尾部往下缩动画  */  public void animation() {  // 开启移动动画  TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),   normal.top);  ta.setDuration(200);  inner.startAnimation(ta);  // 设置回到正常的布局位置  inner.layout(normal.left, normal.top, normal.right, normal.bottom);  normal.setEmpty();  }  // 是否需要开启动画  public boolean isNeedAnimation() {  return !normal.isEmpty();  }  // 回弹动画，header往上缩动画 (使用了属性动画)  public void replyImage() {  final float distance = dropZoomView.getMeasuredWidth() - dropZoomViewWidth;  // 设置动画  ValueAnimator anim = ObjectAnimator.ofFloat(0.0F, 1.0F).setDuration((long) (distance * 0.7));  anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {   @Override   public void onAnimationUpdate(ValueAnimator animation) {   float cVal = (Float) animation.getAnimatedValue();   setZoom(distance - ((distance) * cVal));   }  });  anim.start();  }  //头部缩放  public void setZoom(float s) {  if (dropZoomViewHeight <= 0 || dropZoomViewWidth <= 0) {   return;  }  ViewGroup.LayoutParams lp = dropZoomView.getLayoutParams();  lp.width = (int) (dropZoomViewWidth + s);  lp.height = (int) (dropZoomViewHeight * ((dropZoomViewWidth + s) / dropZoomViewWidth));  dropZoomView.setLayoutParams(lp);  }  /***  * 是否需要移动布局 inner.getMeasuredHeight():获取的是控件的总高度  *  * getHeight()：获取的是屏幕的高度  *  * @return  */  public boolean isNeedMove() {  int offset = inner.getMeasuredHeight() - getHeight();  int scrollY = getScrollY();  // 0是顶部，后面那个是底部  if (scrollY == 0 || scrollY == offset) {   return true;  }  return false;  }  //清理尾部属性值  private void clear0() {  lastX = 0;  lastY = 0;  distanceX = 0;  distanceY = 0;  upDownSlide = false;  } }

<?xml version="1.0" encoding="utf-8"?> <com.kokjuis.travel.customView.BounceZoomScrollView xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:imagecontrol="http://schemas.android.com/apk/res-auto"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:scrollbars="none">  <!-- <LinearLayout   android:id="@+id/ui_allchatlist_header_relativelayout"   android:layout_width="match_parent"   android:layout_height="45dp"   android:background="@drawable/bar_bg"   android:orientation="horizontal"   android:paddingBottom="5dp"   android:paddingTop="5dp">   <Button   android:id="@+id/ui_allchatlist_backbtn"   android:layout_width="wrap_content"   android:layout_height="match_parent"   android:layout_marginBottom="3dp"   android:layout_marginLeft="5dp"   android:layout_marginTop="3dp"   android:background="@null"   android:gravity="center"   android:text="我"   android:textColor="@color/white"   android:textSize="18sp" />  </LinearLayout>  -->  <LinearLayout  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical">  <RelativeLayout   android:layout_width="match_parent"   android:layout_height="250dp"   android:layout_gravity="center_horizontal">   <ImageView   android:layout_width="match_parent"   android:layout_height="match_parent"   android:layout_marginBottom="40dp"   android:background="@drawable/personinfo_bg" />   <com.kokjuis.travel.customView.RoundImageView   android:id="@+id/headImage"   android:layout_width="80dp"   android:layout_height="80dp"   android:layout_alignParentBottom="true"   android:layout_centerHorizontal="true"   android:src="@drawable/headimg"   imagecontrol:border_inside_color="#fff7f2e9"   imagecontrol:border_outside_color="#ffd5d1c8"   imagecontrol:border_thickness="2dp" />  </RelativeLayout>  <LinearLayout   android:layout_width="match_parent"   android:layout_height="wrap_content"   android:orientation="vertical">   <TextView   android:id="@+id/name_tv"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:layout_gravity="center_horizontal"   android:layout_marginTop="6dp"   android:gravity="center_vertical"   android:text="昵称："   android:textSize="20sp" />   <TextView   android:id="@+id/motto_tv"   android:layout_width="wrap_content"   android:layout_height="40dp"   android:layout_gravity="center_horizontal"   android:gravity="center_vertical"   android:text="座右铭："   android:textSize="11sp" />   <LinearLayout   android:layout_width="150dp"   android:layout_height="wrap_content"   android:layout_gravity="center_horizontal"   android:orientation="vertical">   <TextView    android:id="@+id/accounts_tv"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_marginTop="8dp"    android:gravity="center_vertical"    android:text="帐号："    android:textSize="12sp" />   <TextView    android:id="@+id/gender_tv"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_marginTop="2dp"    android:gravity="center_vertical"    android:text="性别："    android:textSize="12sp" />   </LinearLayout>   <Button   android:id="@+id/logout_btn"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:layout_gravity="center_horizontal"   android:layout_marginTop="20dp"   android:text="注销" />  </LinearLayout>  </LinearLayout> </com.kokjuis.travel.customView.BounceZoomScrollView>