In this tutorial, we’ll look at how we can implement TextView such that it auto resizes itself based on the available space and properties specified in our Android Application.

在本教程中，我们将研究如何实现TextView，使其能够根据Android应用程序中指定的可用空间和属性自动调整自身大小。

自动调整TextView的大小 (Auto-Sizing TextView)

Auto-sizing TextView was introduced with Android Oreo. Provided you set the required properties, the text size would automatically change inside its view. Auto-sizing TextView supports backward compatibility all the way till API 4.

Android Oreo引入了自动调整TextView大小的功能。 如果您设置了必需的属性，则文本大小将在其视图内自动更改。 自动调整TextView的大小一直支持向后兼容，直到API 4。

To use Auto-sizing TextView you must use SDK 26 dependency or above:

要使用自动调整TextView大小，您必须使用SDK 26依赖关系或更高版本：

implementation 'com.android.support:appcompat-v7:26.1.0'

Following are the core properties you must add on the TextView to enable Auto-sizing TextView:

以下是您必须在TextView上添加的核心属性才能启用自动调整TextView的大小：

• android:autoSizeTextType – This is set to the value uniform or none. Uniform sizes the text uniformly vertically and horizontallyandroid:autoSizeTextType –设置为统一值或无值。 统一在垂直和水平方向上均匀调整文本大小
• android:autoSizeMaxTextSize – Maximum text size for the TextViewandroid:autoSizeMaxTextSize – TextView的最大文本大小
• android:autoSizeMinTextSize – Minimum text size for the TextViewandroid:autoSizeMinTextSize – TextView的最小文本大小

An Auto-sizing TextView can be defined in the xml as:

可以在xml中将自动调整大小的TextView定义为：

<TextViewandroid:id="@+id/autoTextView"android:layout_width="match_parent"android:layout_height="125dp"android:text="Resizable TextView here."android:autoSizeMaxTextSize="100sp"android:autoSizeMinTextSize="12sp"android:autoSizeTextType="uniform" />

How is the text auto-sized?

文字如何自动调整大小？

There are three ways to do it:

有三种方法可以做到：

• Default – Size changes happen by 1 px. That means granularity is 1 px默认值 -尺寸更改发生1像素。 这表示粒度为1像素
• Granularity – This is a dimension by which the text size increases or decreases in steps between the minimum and maximum text size. Example : android:autoSizeStepGranularity="2sp" increments/decrements the text size by 2 sp.粒度 –这是一个尺寸，文本大小可在最小和最大文本大小之间逐步增大或减小。 示例： android:autoSizeStepGranularity="2sp"将文本大小增加/减少2 sp。
• Presets – This is used to auto-size the text from an array of predefined text size values.预设 –用于从一组预定义的文本大小值中自动调整文本大小。

使用预设 (Using Presets)

We can define the predefined in an arrays.xml in the values folder.

我们可以在values文件夹的arrays.xml中定义预定义。

<resources><array name="autosize"><item>10sp</item><item>30sp</item><item>20sp</item><item>40sp</item><item>100sp</item></array>
</resources>

Set this in the TextView as:

在TextView中将此设置为：

<TextViewandroid:layout_width="match_parent"android:layout_height="200dp"android:autoSizeTextType="uniform"app:autoSizePresetSizes="@array/autosize" />

自动调整Or-Preeo设备的尺寸 (Auto-size for Pre-Oreo Devices)

The above properties work fine only on Android Oreo and above. To make it compatible with the older version we need to do two things:

以上属性仅在Android Oreo及更高版本上可以正常使用。 为了使其与旧版本兼容，我们需要做两件事：

• Use AppCompatTextView widget in place of TextView使用AppCompatTextView小部件代替TextView
• Use app: nomenclature使用app:术语

Define the Auto-size TextView in the XML as:

在XML中定义自动调整大小的TextView为：

<android.support.v7.widget.AppCompatTextViewandroid:layout_width="match_parent"android:layout_height="60dp"android:text="TextView"app:autoSizeMaxTextSize="100sp"app:autoSizeMinTextSize="8sp"app:autoSizeStepGranularity="2sp"app:autoSizeTextType="uniform"/>

以编程方式自动调整TextView的大小 (Auto-size TextView programmatically)

To set properties on the Auto-size TextView programmatically we use the TextViewCompat class.

要以编程方式在自动调整大小的TextView上设置属性，我们使用TextViewCompat类。

You need to pass the TextView instance and the respective sizes for the properties.

您需要传递TextView实例以及属性的相应大小。

Set the autoSize text types as: TextViewCompat.AUTO_SIZE_TEXT_TYPE_NONE or TextViewCompat.AUTO_SIZE_TEXT_TYPE_UNIFORM.

将autoSize文本类型设置为： TextViewCompat.AUTO_SIZE_TEXT_TYPE_NONE或TextViewCompat.AUTO_SIZE_TEXT_TYPE_UNIFORM 。

Setting Presets programmatically:

以编程方式设置预设：

To set the presets programmatically you need to define the arrays.xml differently.

要以编程方式设置预设，您需要不同地定义arrays.xml。

<?xml version="1.0" encoding="utf-8"?>
<resources><array name="autosize"><item>20</item><item>40</item><item>50</item><item>60</item><item>70</item></array>
</resources>

To set it on the TextView do the following:

要在TextView上进行设置，请执行以下操作：

TextViewCompat.setAutoSizeTextTypeUniformWithPresetSizes(textView, getResources().getIntArray(R.array.autosize), TypedValue.COMPLEX_UNIT_SP);

Let’s build an android application that demonstrates the various use cases of Auto-sizing TextView.

让我们构建一个Android应用程序，演示自动调整TextView大小的各种用例。

项目结构 (Project Structure)

码 (Code)

The code for the activity_main.xml layout is given below:

下面给出了activity_main.xml布局的代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"xmlns:app="https://schemas.android.com/apk/res-auto"xmlns:tools="https://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity"><TextViewandroid:id="@+id/textView"android:layout_width="0dp"android:layout_height="125dp"android:background="@android:color/black"android:text="Not resizable TextView. The text size is fixed here."android:textColor="@android:color/white"app:layout_constraintEnd_toStartOf="@+id/autoTextView"app:layout_constraintHorizontal_bias="0.5"app:layout_constraintHorizontal_chainStyle="packed"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/editTextPreset" /><android.support.v7.widget.AppCompatTextViewandroid:id="@+id/autoTextView"android:layout_width="0dp"android:layout_height="125dp"android:background="@android:color/black"android:text="Resizable TextView here. This can vary the text size based on it."android:textColor="@android:color/white"app:autoSizeMaxTextSize="100sp"app:autoSizeMinTextSize="12sp"app:autoSizeStepGranularity="2sp"app:autoSizeTextType="uniform"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintHorizontal_bias="0.5"app:layout_constraintStart_toEndOf="@+id/textView"app:layout_constraintTop_toBottomOf="@+id/editTextPreset" /><android.support.v7.widget.AppCompatTextViewandroid:id="@+id/autoTextViewDynamic"android:layout_width="match_parent"android:layout_height="60dp"android:layout_marginEnd="8dp"android:layout_marginLeft="8dp"android:layout_marginRight="8dp"android:layout_marginStart="8dp"android:layout_marginTop="8dp"android:text="TextView"app:autoSizeMaxTextSize="100sp"app:autoSizeMinTextSize="8sp"app:autoSizeStepGranularity="2sp"app:autoSizeTextType="uniform"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent" /><EditTextandroid:id="@+id/editText"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginEnd="8dp"android:layout_marginLeft="8dp"android:layout_marginRight="8dp"android:layout_marginStart="8dp"android:layout_marginTop="8dp"android:ems="10"android:hint="Enter here"android:maxLines="1"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/autoTextViewDynamic" /><EditTextandroid:id="@+id/editTextPreset"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginEnd="8dp"android:layout_marginLeft="8dp"android:layout_marginRight="8dp"android:layout_marginStart="8dp"android:layout_marginTop="8dp"android:ems="10"android:hint="Enter here for preset size changes"android:maxLines="1"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/editText" /><android.support.v7.widget.AppCompatTextViewandroid:id="@+id/autoTextViewEllipsize"android:layout_width="match_parent"android:layout_height="50dp"android:layout_marginTop="16dp"android:ellipsize="end"android:maxLines="1"android:text="Auto sizing TextView with ellipsize at the end. AppCompat TextVie2"app:autoSizeMaxTextSize="100sp"app:autoSizeMinTextSize="16sp"app:autoSizeStepGranularity="2sp"app:autoSizeTextType="uniform"app:layout_constraintEnd_toEndOf="parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toBottomOf="@+id/textView" /></android.support.constraint.ConstraintLayout>

We’ve added an ellipisize property on one of the Auto-sizing TextView. This way if the content is filled at min text size the remaining Text is truncated

我们在自动调整大小的TextView之一上添加了ellipisize属性。 这样，如果内容以最小文本大小填充，则剩余文本将被截断

The code for the MainActivity.java class is given below:

MainActivity.java类的代码如下：

package com.journaldev.androidautosizingtextview;import android.support.v4.widget.TextViewCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.TypedValue;
import android.widget.EditText;
import android.widget.TextView;public class MainActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);final TextView txtAutoSizeTextViewDynamic = findViewById(R.id.autoTextViewDynamic);final TextView textView = findViewById(R.id.textView);EditText editText = findViewById(R.id.editText);EditText editTextWithPresetChanges = findViewById(R.id.editTextPreset);editText.addTextChangedListener(new TextWatcher() {@Overridepublic void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {}@Overridepublic void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {txtAutoSizeTextViewDynamic.setText(charSequence.toString());}@Overridepublic void afterTextChanged(Editable editable) {}});editTextWithPresetChanges.addTextChangedListener(new TextWatcher() {@Overridepublic void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {TextViewCompat.setAutoSizeTextTypeUniformWithPresetSizes(textView, getResources().getIntArray(R.array.autosize), TypedValue.COMPLEX_UNIT_SP);}@Overridepublic void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {textView.setText(charSequence);}@Overridepublic void afterTextChanged(Editable editable) {}});}
}

We’ve added TextWatchers on two of the EditTexts which will update the Auto-sizing TextViews whenever the edit text is changed.

我们已经在两个EditText上添加了TextWatchers，它们将在更改编辑文本时更新自动调整大小的TextView。

We’ve changed the normal text view to an auto-sizing one when text is entered in the second EditText.

在第二个EditText中输入文本时，我们已将普通文本视图更改为自动调整大小的视图。

The output of the above application in action is given below:

上面应用程序的输出如下：

This brings an end to this tutorial. You can download the project from the link below:

本教程到此结束。 您可以从下面的链接下载项目：

翻译自: https://www.journaldev.com/22399/android-auto-sizing-textview