修复了 ViewPager 内容布局中的视图，在 CoordinatorLayout 下

Question

我的应用有一个 Activity 和 TabLayout，以及 3 个 Fragments。在 Activity's 布局中，我有 CoordinatorLayout 和 ViewPager。我还需要为 toolbar 设置动画。现在在 Fragments 布局中，我需要在底部放置一个固定的 TextView。下面给出的是 activity 的 XML 和片段。

I am facing the problem that this fixed TextView in Fragment's layout is going under the bottom navigation bar and is scrolling also, that I don't want.

怎样才能做到这一点？

activity.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/clMain"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/app_name"
                android:textColor="#FFFFFF"
                android:textSize="22sp"
                android:textStyle="bold" />
        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</android.support.design.widget.CoordinatorLayout>

fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:background="@color/colorWhite"
    android:orientation="vertical">

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/rlParent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="fill_vertical"
        android:layout_weight="1"
        android:fitsSystemWindows="true"
        android:orientation="vertical">


    </android.support.v4.widget.NestedScrollView>

    <TextView
        android:id="@+id/tvConfirmOrder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorDarkGreen"
        android:gravity="center"
        android:padding="10dp"
        android:text="@string/confirm_order"
        android:textColor="@color/colorWhite"
        android:textSize="18sp"
        android:textStyle="bold"></TextView>
</LinearLayout>

Answer 1

由于您希望每个片段的底部固定 TextView，因此可以通过将您的 TextView 转移到 activity.xml 并向其添加自定义行为来解决。

因此，首先，创建一个代表自定义行为的class：

public class FixedBottomViewBehavior extends CoordinatorLayout.Behavior<View> {

    public FixedBottomViewBehavior() {
    }

    public FixedBottomViewBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, View child, View dependency) {
        //making our bottom view depends on ViewPager (or whatever that have appbar_scrolling_view_behavior behavior)
        return dependency instanceof ViewPager;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {
        if (ViewCompat.isLaidOut(parent)) {
            //attach our bottom view to the bottom of CoordinatorLayout
            child.setY(parent.getBottom() - child.getHeight());

            //set bottom padding to the dependency view to prevent bottom view from covering it
            dependency.setPadding(dependency.getPaddingLeft(), dependency.getPaddingTop(),
                    dependency.getPaddingRight(), child.getHeight());
        }
        return false;
    }
}

这里没有魔法，我们只是让我们的底部视图依赖于带有 appbar_scrolling_view_behavior 的某个视图（在我们的例子中是 ViewPager），然后将它附加到 [= 的底部18=] 并设置一些填充到依赖项。

其次，更改你的activity.xml，在其中添加你的TextView：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/clMain"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <TextView
                android:id="@+id/toolbar_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/app_name"
                android:textColor="#FFFFFF"
                android:textSize="22sp"
                android:textStyle="bold" />
        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <TextView
        android:id="@+id/tvConfirmOrder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/colorDarkGreen"
        android:gravity="center"
        android:padding="10dp"
        android:text="@string/confirm_order"
        android:textColor="@color/colorWhite"
        android:textSize="18sp"
        android:textStyle="bold"
        app:layout_behavior="your.package.name.FixedBottomViewBehavior" />

</android.support.design.widget.CoordinatorLayout>

确保您已从 fragment.xml 中删除 TextView。也不要忘记将 your.package.name.FixedBottomViewBehavior 准确更改为您的包名称。

瞧！适当的工具栏动画和底部的固定视图应该很有魅力。

此外： 如果您不知道如何将 OnClick 事件传递给您的片段，您可以按照这样在你的 Activity:

    public interface OnConfirmOrderClickListener {
        void onConfirmOrderClick(View v);
    }

    public Fragment getActiveFragment() {
        String name = makeFragmentName(pager.getId(), pager.getCurrentItem());
        return getSupportFragmentManager().findFragmentByTag(name);
    }

    public String makeFragmentName(int viewId, int index) {
        return "android:switcher:" + viewId + ":" + index;
    } 

    tvConfirmOrder.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Fragment current = getActiveFragment();
            if (current instanceof OnConfirmOrderClickListener)
                ((OnConfirmOrderClickListener) current).onConfirmOrderClick(v);
        }
    });

别忘了制作片段implements OnConfirmOrderClickListener。希望对您有所帮助！

Answer 2

对于那些希望按钮仅出现在一个片段中的用户，可以使用 onPageChangeListener 或 ViewPager 使按钮随 ViewPager

一起滚动

viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        updateButtonPosition(position, positionOffsetPixels);
    }
});


//Move the button according to the tab you want it to be fixed. 
//Here is the 3rd tab of a 3 tab viewPager, for instance
private void updateButtonPosition(int position, int positionOffsetPixels) {
    int fixedRewardXPos;
    if (position == 0) {
        fixedRewardXPos = viewPager.getWidth() * 2 - positionOffsetPixels;
    } else if (position == 1) {
        fixedRewardXPos = viewPager.getWidth() - positionOffsetPixels;
    } else {
        fixedRewardXPos = -positionOffsetPixels;
    }

    //Add getLeft() to keep the button to its former position in it's fragment
    aButton.setX(fixedRewardXPos + aButton.getLeft());
}

修复了 ViewPager 内容布局中的视图，在 CoordinatorLayout 下

Fixed view in ViewPager's content layout, under CoordinatorLayout

android

android-viewpager

material-design

android-coordinatorlayout

android-appbarlayout