这篇文章给大家介绍怎么在Android中利用ScrollView 实现一个伸缩放大效果，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
核心的控件就是下面的这段代码：
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; 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); } } } @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); } 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; } } 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); } 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; } }下面是我自己使用的一个layout例子：
<?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>关于怎么在Android中利用ScrollView 实现一个伸缩放大效果就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
