当我在我的协调器布局中在xml中设置锚点时，我看到onDependentViewChanged函数被无限调用。如果我没有设置锚点，则不会重复调用它，只会在我实际滚动（正确）时调用它，但是一旦我设置了锚点，它就会在页面加载时无限调用，而不会触及滚动条。但后来我的东西并没有摆放到我想要的位置。
我知道我必须遗漏一些东西，但没有一个例子讨论这个问题。它只会在我尝试设置锚点时发生。
public class ViewBehavior extends CoordinatorLayout.Behavior<HeaderView> {
private Context mContext;
private int mStartMarginLeft;
private int mEndMargintLeft;
private int mMarginRight;
private int mStartMarginBottom;
private boolean isHide;
public ViewBehavior(Context context, AttributeSet attrs) {
mContext = context;
}
@Override
public boolean layoutDependsOn(CoordinatorLayout parent, HeaderView child, View dependency) {
return dependency instanceof LinearLayout;
}
@Override
public boolean onDependentViewChanged(CoordinatorLayout parent, HeaderView child, View dependency) {
shouldInitProperties(child, dependency);
int maxScroll = 100;//((AppBarLayout) dependency).getTotalScrollRange();
float percentage = Math.abs(dependency.getY()) / (float) maxScroll;
float childPosition = dependency.getHeight()
+ dependency.getY()
- child.getHeight()
- (getToolbarHeight() - child.getHeight()) * percentage / 2;
childPosition = childPosition - mStartMarginBottom * (1f - percentage);
Log.d("CHILD POSTION ", "" + childPosition);
CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) child.getLayoutParams();
lp.leftMargin = (int) (percentage * mEndMargintLeft) + mStartMarginLeft;
lp.rightMargin = mMarginRight;
child.setLayoutParams(lp);
child.setY(childPosition);
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
if (isHide && percentage < 1) {
child.setVisibility(View.VISIBLE);
isHide = false;
} else if (!isHide && percentage == 1) {
child.setVisibility(View.GONE);
isHide = true;
}
}
return false;
}
private void shouldInitProperties(HeaderView child, View dependency) {
if (mStartMarginLeft == 0)
mStartMarginLeft = mContext.getResources().getDimensionPixelOffset(R.dimen.header_view_start_margin_left);
if (mEndMargintLeft == 0)
mEndMargintLeft = mContext.getResources().getDimensionPixelOffset(R.dimen.header_view_end_margin_left);
if (mStartMarginBottom == 0)
mStartMarginBottom = mContext.getResources().getDimensionPixelOffset(R.dimen.header_view_start_margin_bottom);
if (mMarginRight == 0)
mMarginRight = mContext.getResources().getDimensionPixelOffset(R.dimen.header_view_end_margin_right);
}
public int getToolbarHeight() {
int result = 0;
TypedValue tv = new TypedValue();
if (mContext.getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) {
result = TypedValue.complexToDimensionPixelSize(tv.data, mContext.getResources().getDisplayMetrics());
}
return result;
}
}
XML
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@color/transparent"
android:fitsSystemWindows="true">
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="@+id/appBarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
android:layout_marginTop="0dp"
android:fitsSystemWindows="true">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap"
android:fitsSystemWindows="true">
<LinearLayout
android:id="@+id/main.framelayout.title"
android:layout_width="match_parent"
android:layout_height="200dp"
android:background="@color/lightGreen"
android:orientation="vertical"
app:layout_collapseMode="parallax"
android:fitsSystemWindows="true"
>
</LinearLayout>
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
>
<include
android:id="@+id/toolbar_header_view"
layout="@layout/header_view"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:visibility="gone"
/>
</android.support.v7.widget.Toolbar>
</android.support.design.widget.CollapsingToolbarLayout>
<android.support.constraint.ConstraintLayout
android:id="@+id/cardConstraintLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:background="@drawable/gradient"
android:layout_marginTop="0dp"
android:visibility="visible">
<android.support.v4.view.ViewPager
android:id="@+id/viewPager"
android:layout_width="0dp"
android:layout_height="175dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0"
android:paddingBottom="50dp"/>
<android.support.design.widget.TabLayout
android:layout_width="wrap_content"
android:layout_height="20dp"
android:id="@+id/viewPagerIndicator"
app:tabBackground="@drawable/pager_indicator_selector_gray"
app:tabGravity="center"
app:tabIndicatorHeight="0dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="@id/viewPager"
android:layout_marginBottom="10dp"/>
</android.support.constraint.ConstraintLayout>
</android.support.design.widget.AppBarLayout>
<include
android:id="@+id/float_header_view"
layout="@layout/header_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_behavior="com.test.ViewBehavior"
app:layout_anchorGravity="top"
/>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
</android.support.v7.widget.RecyclerView>
</android.support.design.widget.CoordinatorLayout>
</RelativeLayout>