Question

我有一个 LinearLayout ，每个视图都按照其权重值填充空间。

我有一个layout_weight 8的片段和一个layout_weight 2的TextView。

这是下图：

使用以下代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    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"
    xmlns:tools="http://schemas.android.com/tools"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:orientation="vertical">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="8"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:padding="20dp"
        android:layout_weight="2"
        app:layout_constraintVertical_weight="2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        tools:text="Lorem Ipsum is simply dummy text \nof the printing and typesetting industry" />

</LinearLayout>

现在，将其转换为 ConstraintLayout 后，我发现很难通过使用约束链定义加权布局来复制它。

片段充满了屏幕，TextView位于屏幕顶部，而不是仅占用layout_constraintVertical_weight = 8和layout_constraintVertical_weight = 2的指定空间。

这是下图：

使用以下代码：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    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"
    xmlns:tools="http://schemas.android.com/tools"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintVertical_chainStyle="spread"
        app:layout_constraintVertical_weight="8"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:padding="20dp"
        app:layout_constraintVertical_weight="2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        tools:text="Lorem Ipsum is simply dummy text \nof the printing and typesetting industry" />

</androidx.constraintlayout.widget.ConstraintLayout>

根据文档，它说using the layout_constraintHorizontal_weight and layout_constraintVertical_weight attributes. If you're familiar with layout_weight in a linear layout, this works the same way.不适用于我，或者我执行的方式有误。

如何将我的LinearLayout正确转换为约束布局？

Answer 1

要链接视图，您需要将它们彼此绑定。在您的xml中，您需要将片段app:layout_constraintBottom_toBottomOf="parent"更改为app:layout_constraintBottom_toTopOf="@+id/textView2"并将app:layout_constraintTop_toBottomOf="@id/nav_host_fragment"添加到TextView。

此外，我将片段和TextView的android:layout_width="match_parent"更改为android:layout_width="0dp"，因为使用0dp在约束之间扩展视图是正确的。

这是解决方案。

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:app="http://schemas.android.com/apk/res-auto"
    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"
    xmlns:tools="http://schemas.android.com/tools"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    android:orientation="vertical">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toTopOf="@id/textView2"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_weight="8"/>

    <TextView
        android:id="@+id/textView2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:padding="20dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@id/nav_host_fragment"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintVertical_weight="2"
        tools:text="Lorem Ipsum is simply dummy text \nof the printing and typesetting industry" />

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 2

对于片段，您使用了错误的底部约束。片段底部约束应位于textview的顶部。

此外，您无需使用layout_constraintVertical_chainStyle

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/textView2"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_weight="8"
        app:navGraph="@navigation/nav_graph" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:padding="20dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintVertical_weight="2"
        tools:text="Lorem Ipsum is simply dummy text \nof the printing and typesetting industry" />

</androidx.constraintlayout.widget.ConstraintLayout>

第二种方式->同样，您也可以不用重量。如果没有layout_constraintVertical_weight，则可以使用指南。

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/guideline"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.9" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:padding="20dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/guideline"
        tools:text="Lorem Ipsum is simply dummy text \nof the printing and typesetting industry" />

</androidx.constraintlayout.widget.ConstraintLayout>

如何使用约束布局实现垂直链接

2 个答案: