PercentFrameLayout:您必须提供layout_width属性 [英] PercentFrameLayout: You must supply a layout_width attribute

问题描述

我尝试使用 PercentFrameLayout ，但收到以下错误消息:

I try to use a PercentFrameLayout but I get this error message:

Binary XML file line #: You must supply a layout_width attribute.

这是我使用的xml:

<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">

    <ImageView
        app:layout_heightPercent="50%"
        app:layout_marginLeftPercent="25%"
        app:layout_marginTopPercent="25%"
        app:layout_widthPercent="50%"/>
</android.support.percent.PercentFrameLayout>

这是错误还是我的错误?

Is this a bug or is it my mistake?

推荐答案

由于XML布局规范，仍然需要layout_width和layout_height属性，但是在PercentFrameLayout或PercentRelativeLayout中实际上将忽略它们.

The layout_width and layout_height attributes are still required due to the XML layout specifications, but are effectively ignored in a PercentFrameLayout or PercentRelativeLayout.

您只需要将值设置为0dp或wrap_content:

You just have to set the values to 0dp or wrap_content:

<ImageView
    android:layout_height="0dp"
    android:layout_width="0dp"
    app:layout_heightPercent="50%"
    app:layout_marginLeftPercent="25%"
    app:layout_marginTopPercent="25%"
    app:layout_widthPercent="50%" />

这与标准LinearLayout和layout_weight的用法类似，在该情况下，您也必须指定layout_width.

This is similar to the usage of a standard LinearLayout with layout_weight where you have to specify a layout_width too.

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