public class MainActivity extends AppCompatActivity { private CircleImageView ivPortrait; private ObservableScrollView scrollView; private ViewGroup.MarginLayoutParams marginLayoutParams; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } private void initView() { ivPortrait = (CircleImageView) findViewById(R.id.iv_portrait); scrollView = (ObservableScrollView) findViewById(R.id.scrollView); marginLayoutParams = new ViewGroup.MarginLayoutParams(ivPortrait.getLayoutParams()); scrollView.setScrollViewListener(new ObservableScrollView.ScrollViewListener() { @Override public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy) { // 設置頭像距離頂部的距離 int top = dp2px(70) - y; if (top < dp2px(10)) {  // 固定在標題欄  marginLayoutParams.setMargins(dp2px(20), dp2px(10), 0, 0); } else {  // 向上移動  marginLayoutParams.setMargins(dp2px(20), dp2px(70) - y, 0, 0); } // 根據向上滑動的距離設置頭像的大小 FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(marginLayoutParams); // 頭像最大為45dp，最小為30dp int height = dp2px(45) - y < dp2px(30) ? dp2px(30) : dp2px(45) - y; layoutParams.height = height; layoutParams.width = height; ivPortrait.setLayoutParams(layoutParams); } }); } private int dp2px(float dp) { return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, getResources().getDisplayMetrics()); }}

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFF"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <RelativeLayout android:layout_width="match_parent" android:layout_height="50dp" android:background="#F2F4F7"> ... </RelativeLayout> <com.yl.jdfinanceindex.ObservableScrollView android:id="@+id/scrollView" android:layout_width="match_parent" android:layout_height="match_parent" android:overScrollMode="never" android:scrollbars="none"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <RelativeLayout  android:layout_width="match_parent"  android:layout_height="80dp"  android:background="#F2F4F7">  ... </RelativeLayout> <View  android:layout_width="match_parent"  android:layout_height="1000dp" /> </LinearLayout> </com.yl.jdfinanceindex.ObservableScrollView> </LinearLayout> <com.yl.jdfinanceindex.CircleImageView android:id="@+id/iv_portrait" android:layout_width="45dp" android:layout_height="45dp" android:layout_marginLeft="20dp" android:layout_marginTop="70dp" android:src="@mipmap/ic_portrait" /></FrameLayout>

public class ObservableScrollView extends ScrollView { private ScrollViewListener scrollViewListener; public ObservableScrollView(Context context) { super(context); } public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public ObservableScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public void setScrollViewListener(ScrollViewListener scrollViewListener) { this.scrollViewListener = scrollViewListener; } @Override protected void onScrollChanged(int x, int y, int oldx, int oldy) { super.onScrollChanged(x, y, oldx, oldy); if (scrollViewListener != null) { scrollViewListener.onScrollChanged(this, x, y, oldx, oldy); } } public interface ScrollViewListener { void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy); }}