我正在尝试使用约束布局,如下所示。但在实际布局中不考虑纵横比。相反,高度实际上是将内容包装在里面
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/content"
android:layout_height="0dp"
android:layout_width="match_parent">
<!-- some content inside -->
</android.support.constraint.ConstraintLayout>
我认为这可能是因为我没有设置width="0dp"
(让约束决定宽度)。所以我尝试了下面的另一种方式。但随后宽度变为零。
这样做的正确方法是什么?
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/content"
android:layout_height="0dp"
android:layout_width="0dp"
app:layout_constraintStart_toEndOf="parent"
app:layout_constraintEnd_toEndOf="parent">
<!-- some content inside -->
</android.support.constraint.ConstraintLayout>
编辑:工作解决方案受到Anddenver的回答(修改)的启发:
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto">
<FrameLayout
android:background="@android:color/holo_green_dark"
android:layout_width="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="2:1">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
进一步编辑:
看来我需要为我的内部内容包装一层约束布局....:
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto">
<FrameLayout
android:background="@android:color/holo_green_dark"
android:layout_width="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="2:1">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<actual contents here..../>
</android.support.constraint.ConstraintLayout>
</FrameLayout>
</android.support.constraint.ConstraintLayout>
或者,只需删除FrameLayout
,并在ConstraintLayout
中包装ConstraintLayout
:
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto">
<android.support.constraint.ConstraintLayout
android:background="@android:color/holo_green_dark"
android:layout_width="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="2:1">
contents here...
</android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>
你需要内部视图,例如:
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<FrameLayout
android:background="@color/colorPrimary"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="1:1">
<YOUR CONTENT>
</FrameLayout>
对于ListView,你需要给定制的list_item.xml
充气
这应该是H,2:1
,以将高度限制为2:1
纵横比。
默认的android.R.layout.simple_list_item_1
只是一个TextView
:
<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/text1"
android:layout_height="0dp"
android:layout_width="0dp"
app:layout_constraintDimensionRatio="H,2:1"
...
/>