简单述说
最近没有什么事情，就看到了京东的首页，感觉还不错，但是我目前也只是粗略的模仿了出来。
github 地址
V2版本
仿京东首页.gif
设计思路
简单画图.png
滚动黄色的recycleView，和viewPager里面的RecyclerView，都需要先确认Frame的位置，如果Frame的translationY == 0了，就只能滚动黄色的recyclerView，如果Frame的translationY == -Frame.getHeight()，就只能滚动viewPager里面的recyclerview了，如果处于-Frame.getHeight() < translationY < 0 都将滚动事件给吃掉，都不让其滚动。这里MyMainLinLerLayout，是继承了LinLayout的，里面实现了 NestedScrollingParent3，当我们滚动viewPager里面的recyclerview的时候，我们会收到 onStartNestedScroll 的回调通知，我们将其返回true，这样最顶层的CoordinatorLayout，就不会收到滚动通知事件了
此次总结
1、如果顶层是CoordinatorLayout，子容器为MyMainLinLerLayout，MyMainLinLerLayout并实现了NestedScrollingParent3，当MyMainLinLerLayout 子容器里面的recyclerview滚动的时候，会通知MyMainLinLerLayout 里面的onStartNestedScroll方法，如果被MyMainLinLerLayout里面的onStartNestedScroll方法拦截了，不会继续将事件返回给CoordinatorLayout里面的onStartNestedScroll
核心代码展示
xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_behavior="@string/main_myframe_behaivor">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/main_header_recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</FrameLayout>
<com.example.imitationjd.weiget.MyMainLinLerLayout
android:id="@+id/first_my_linlayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_behavior=".behavior.main.MainMyLinlayoutBehavior">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/ctl_first_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
...省略部分代码
</LinearLayout>
<LinearLayout
android:id="@+id/ll_first_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent">
...省略部分代码
</LinearLayout>
<LinearLayout
android:id="@+id/ll_first_title_desc"
android:layout_width="match_parent"
android:layout_height="@dimen/first_title_desc"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="@+id/ll_first_title">
...省略部分代码
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.viewpager.widget.ViewPager
android:id="@+id/first_viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</com.example.imitationjd.weiget.MyMainLinLerLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
public class MainMyLinlayoutBehavior extends CoordinatorLayout.Behavior<MyMainLinLerLayout> {
private int titleHeight = 0;
@Override
public boolean layoutDependsOn(@NonNull CoordinatorLayout parent, @NonNull MyMainLinLerLayout child, @NonNull View dependency) {
return dependency instanceof FrameLayout;
}
@Override
public boolean onDependentViewChanged(@NonNull CoordinatorLayout parent, @NonNull MyMainLinLerLayout child, @NonNull View dependency) {
if (titleHeight == 0) {
titleHeight = child.findViewById(R.id.ctl_first_layout).getHeight();
}
FrameLayout frameLayout = (FrameLayout) dependency;
float transY = frameLayout.getHeight() + frameLayout.getTranslationY() / frameLayout.getHeight() * frameLayout.getHeight();
if (transY < 0) {
transY = 0;
}
child.setTranslationY(transY);
return true;
}
}
public class MainMyFrameLayoutBehavior extends CoordinatorLayout.Behavior<FrameLayout> {
...省略部分代码
@Override
public void onNestedPreScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull FrameLayout child, @NonNull View target, int dx, int dy, @NonNull int[] consumed, int type) {
super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
if (myMainLinLerLayout == null) {
myMainLinLerLayout = coordinatorLayout.findViewById(R.id.first_my_linlayout);
}
if (target instanceof RecyclerView) {
float transY = child.getTranslationY() - dy;
if (target.getId() == R.id.main_header_recyclerview) {
RecyclerView recyclerView = (RecyclerView) target;
mainRecyclerView = recyclerView;
if (dy > 0) {//手指向上
if (recyclerView.canScrollVertically(dy)) {
recyclerView.scrollBy(0, dy);
} else {
if (child.getTranslationY() < -child.getHeight()) {
transY = -child.getHeight();
}
child.setTranslationY(transY);
}
}
if (dy < 0) {//手指向下
if (child.getTranslationY() == 0) {
child.setTranslationY(0);
recyclerView.scrollBy(0, dy);
} else {
if (child.getTranslationY() > -child.getHeight()) {
if (child.getTranslationY() > 0) {
child.setTranslationY(0);
} else {
if (child.getTranslationY() + transY > 0) {
transY = 0;
}
consumed[1] = dy;
child.setTranslationY(transY);
}
if (child.getTranslationY() == 0) {
recyclerView.scrollBy(0, dy);
}
} else {
recyclerView.scrollBy(0, dy);
}
}
}
} else if (target.getId() == R.id.fragment_recyclerview) { //viewpager里面的Recyclerview
if (dy > 0) {//手指向上
if (myMainLinLerLayout.getTranslationY() != 0) {
if (transY < -child.getHeight()) {
transY = -child.getHeight();
}
child.setTranslationY(transY);
consumed[1] = dy;
}
}
if (dy < 0) {//手指向下
if (transY > -child.getHeight() && transY < 0) {
child.setTranslationY(transY);
} else if (transY >0){
if (mainRecyclerView!=null){
mainRecyclerView.scrollBy(0,dy);
}
child.setTranslationY(0);
}
consumed[1] = dy;
}
}
}
}
}
