Percent Layouts
suggest changeThe Percent Support Library provides PercentFrameLayout
and PercentRelativeLayout
, two ViewGroups that provide an easy way to specify View dimensions and margins in terms of a percentage of the overall size.
You can use the Percent Support Library by adding the following to your dependencies.
compile 'com.android.support:percent:25.3.1'
If you wanted to display a view that fills the screen horizontally but only half the screen vertically you would do thie following.
<android.support.percent.PercentFrameLayout
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
app:layout_widthPercent="100%"
app:layout_heightPercent="50%"
android:background="@android:color/black" />
<android.support.percent.PercentFrameLayout>
You can also define the percentages in a separate XML file with code such as:
<fraction name="margin_start_percent">25%</fraction>
And refer to them in your layouts with @fraction/margin_start_percent
.
They also contain the ability to set a custom aspect ratio via app:layout_aspectRatio
.
This allows you to set only a single dimension, such as only the width, and the height will be automatically determined based on the aspect ratio you’ve defined, whether it is 4:3 or 16:9 or even a square 1:1 aspect ratio.
For example:
<ImageView
app:layout_widthPercent="100%"
app:layout_aspectRatio="178%"
android:scaleType="centerCrop"
android:src="@drawable/header_background"/>