Android仿京东金融首页头像效果

publicclassMainActivityextendsAppCompatActivity {

 privateCircleImageView ivPortrait;

 privateObservableScrollView scrollView;

 privateViewGroup.MarginLayoutParams marginLayoutParams;

 @Override

 protectedvoidonCreate(Bundle savedInstanceState) {

 super.onCreate(savedInstanceState);

 setContentView(R.layout.activity_main);

 initView();

 }

 privatevoidinitView() {

 ivPortrait = (CircleImageView) findViewById(R.id.iv_portrait);

 scrollView = (ObservableScrollView) findViewById(R.id.scrollView);

 marginLayoutParams =newViewGroup.MarginLayoutParams(ivPortrait.getLayoutParams());

 scrollView.setScrollViewListener(newObservableScrollView.ScrollViewListener() {

 @Override

 publicvoidonScrollChanged(ObservableScrollView scrollView,intx,inty,intoldx,intoldy) {

 // 设置头像距离顶部的距离

 inttop = dp2px(70) - y;

 if(top < dp2px(10)) {

  // 固定在标题栏

  marginLayoutParams.setMargins(dp2px(20), dp2px(10),0,0);

 }else{

  // 向上移动

  marginLayoutParams.setMargins(dp2px(20), dp2px(70) - y,0,0);

 }

 // 根据向上滑动的距离设置头像的大小

 FrameLayout.LayoutParams layoutParams =newFrameLayout.LayoutParams(marginLayoutParams);

 // 头像最大为45dp，最小为30dp

 intheight = dp2px(45) - y < dp2px(30) ? dp2px(30) : dp2px(45) - y;

 layoutParams.height = height;

 layoutParams.width = height;

 ivPortrait.setLayoutParams(layoutParams);

 }

 });

 }

 privateintdp2px(floatdp) {

 return(int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,

 getResources().getDisplayMetrics());

 }

}

 android:layout_width="match_parent"

 android:layout_height="match_parent"

 android:background="#FFF">

 android:layout_width="match_parent"

 android:layout_height="match_parent"

 android:orientation="vertical">

 android:layout_width="match_parent"

 android:layout_height="50dp"

 android:background="#F2F4F7">

 ...

 android:id="@+id/scrollView"

 android:layout_width="match_parent"

 android:layout_height="match_parent"

 android:overScrollMode="never"

 android:scrollbars="none">

 android:layout_width="match_parent"

 android:layout_height="match_parent"

 android:orientation="vertical">

  android:layout_width="match_parent"

  android:layout_height="80dp"

  android:background="#F2F4F7">

  ...

  android:layout_width="match_parent"

  android:layout_height="1000dp"/>

 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"/>

publicclassObservableScrollViewextendsScrollView {

 privateScrollViewListener scrollViewListener;

 publicObservableScrollView(Context context) {

 super(context);

 }

 publicObservableScrollView(Context context, AttributeSet attrs,intdefStyle) {

 super(context, attrs, defStyle);

 }

 publicObservableScrollView(Context context, AttributeSet attrs) {

 super(context, attrs);

 }

 publicvoidsetScrollViewListener(ScrollViewListener scrollViewListener) {

 this.scrollViewListener = scrollViewListener;

 }

 @Override

 protectedvoidonScrollChanged(intx,inty,intoldx,intoldy) {

 super.onScrollChanged(x, y, oldx, oldy);

 if(scrollViewListener !=null) {

 scrollViewListener.onScrollChanged(this, x, y, oldx, oldy);

 }

 }

 publicinterfaceScrollViewListener {

 voidonScrollChanged(ObservableScrollView scrollView,intx,inty,intoldx,intoldy);

 }

}