如何对XML中的字体使用指定的权重

问题描述

使用 XML字体功能，您可以为字体系列指定各种字体粗细.例如:

Using the Fonts in XML feature you can specify various font weights for a font family. For example:

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:app="http://schemas.android.com/apk/res-auto">

    <font android:font="@font/archivo_narrow_regular" android:fontWeight="400" android:fontStyle="normal"
        app:font="@font/archivo_narrow_regular" app:fontWeight="400" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_regular_italic" android:fontWeight="400" android:fontStyle="italic"
        app:font="@font/archivo_narrow_regular_italic" app:fontWeight="400" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_medium" android:fontWeight="500" android:fontStyle="normal"
        app:font="@font/archivo_narrow_medium" app:fontWeight="500" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_medium_italic" android:fontWeight="500" android:fontStyle="italic"
        app:font="@font/archivo_narrow_medium_italic" app:fontWeight="500" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_semibold" android:fontWeight="600" android:fontStyle="normal"
        app:font="@font/archivo_narrow_semibold" app:fontWeight="600" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_semibold_italic" android:fontWeight="600" android:fontStyle="italic"
        app:font="@font/archivo_narrow_semibold_italic" app:fontWeight="600" app:fontStyle="italic"/>

    <font android:font="@font/archivo_narrow_bold" android:fontWeight="700" android:fontStyle="normal"
        app:font="@font/archivo_narrow_bold" app:fontWeight="700" app:fontStyle="normal"/>

    <font android:font="@font/archivo_narrow_bold_italic" android:fontWeight="700" android:fontStyle="italic"
        app:font="@font/archivo_narrow_bold_italic" app:fontWeight="700" app:fontStyle="italic"/>

</font-family>

但是我无法弄清楚如何真正利用这些权重.可以是XML(布局/样式)文件中的内容，也可以是Java代码中的形式.它们不是TextView可用的fontWeight属性，并且 Typeface 对象是从 ResourcesCompat.getFont(context, R.font.archivo_narrow) 没有提及字体粗细.

But I cannot figure out how to actually make use of each of these weights; either in an XML (layout/style) file, or in Java code. Their is no fontWeight attribute available for TextView, and the Typeface object created from ResourcesCompat.getFont(context, R.font.archivo_narrow) has no mention of font weights.

我意识到我只能指定特定的字体资源(即R.font.archivo_narrow_semibold)，但是在font-family中具有fontWeight属性的意义是什么?

I realize that I can just specify the specific font resource (i.e. R.font.archivo_narrow_semibold), but then what is the point of having a fontWeight attribute in the font-family?

新的静态 create(Typeface family, int weight, boolean italic) 方法是在API级别28中添加的，以及 getWeight() 实例方法.最终，这使得可以使用Java代码中的fontWeight属性.尽管仅适用于API级别28及以上，但我在支持库中找不到任何类似物.

A new static create(Typeface family, int weight, boolean italic) method was added in API Level 28, along with a getWeight() instance method. This finally makes it possible to make use of the fontWeight attribute in Java code; though only for API Level 28 and above, I haven't found any analogs in the support library.

这很有用-并且表明fontWeight属性过去没有任何作用-但我真的很希望能够在XML样式中使用权重.

This is useful—and shows that the fontWeight attribute didn't serve any purpose in the past—but I would really like to be able to use the weight in XML styling.

推荐答案

@FlorianWalther指出， TextView.textFontWeight 属性正是我想要的.此属性显然是在API级别28中添加的，但是直到最近才被记录.

As pointed out by @FlorianWalther, the TextView.textFontWeight attribute is exactly what I was looking for. This attribute was apparently added in API level 28, but was not documented until recently.

确保所有权重都在同一个XML文件中(就像在我的问题中一样)，然后只需将属性与fontFamily属性一起使用.

Make sure all of the weights are in the same XML file (as in my question), then simply use the attribute along with the fontFamily attribute.

<TextView android:id="@+id/weightedTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:fontFamily="@font/archivo_narrow"
    android:textFontWeight="700"/>

据我所知，此属性仅在以上API级别28中可用，如果在支持库中找到对应的属性，我将进行更新.

As far as I am aware this attribute is only available in API Level 28 an above, I will update if I find its counterpart in the support library.

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