在2017年谷歌IO大会上，谷歌介绍了TextView的autoSize属性

https://youtu.be/fjUdJ2aVqE4

<android.support.v7.widget.AppCompatTextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/my_text"
        app:autoSizeTextType="uniform"
        app:autoSizeMaxTextSize="10sp"
        app:autoSizeMinTextSize="6sp"
        app:autoSizeStepGranularity="1sp"/>

你可以使用android.text.StaticLayout类。这就是TextView内部使用的。

扩展TextView和覆盖onDraw与下面的代码。它将保持文本纵横比，但将其大小填充空间。如果需要，您可以轻松地修改代码以进行拉伸。

  @Override
  protected void onDraw(@NonNull Canvas canvas) {
    TextPaint textPaint = getPaint();
    textPaint.setColor(getCurrentTextColor());
    textPaint.setTextAlign(Paint.Align.CENTER);
    textPaint.drawableState = getDrawableState();

    String text = getText().toString();
    float desiredWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight() - 2;
    float desiredHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom() - 2;
    float textSize = textPaint.getTextSize();

    for (int i = 0; i < 10; i++) {
      textPaint.getTextBounds(text, 0, text.length(), rect);
      float width = rect.width();
      float height = rect.height();

      float deltaWidth = width - desiredWidth;
      float deltaHeight = height - desiredHeight;

      boolean fitsWidth = deltaWidth <= 0;
      boolean fitsHeight = deltaHeight <= 0;

      if ((fitsWidth && Math.abs(deltaHeight) < 1.0)
          || (fitsHeight && Math.abs(deltaWidth) < 1.0)) {
        // close enough
        break;
      }

      float adjustX = desiredWidth / width;
      float adjustY = desiredHeight / height;

      textSize = textSize * (adjustY < adjustX ? adjustY : adjustX);

      // adjust text size
      textPaint.setTextSize(textSize);
    }
    float x = desiredWidth / 2f;
    float y = desiredHeight / 2f - rect.top - rect.height() / 2f;
    canvas.drawText(text, x, y, textPaint);
  }

我从Chase的AutoResizeTextView类开始，并做了一个微小的更改，以便它可以垂直和水平地适应。

我还发现了一个bug，在一些相当模糊的条件下，在布局编辑器(在Eclipse中)中导致空指针异常。

更改1:垂直和水平对齐文本

Chase的原始版本减小了文本大小，直到垂直对齐，但允许文本比目标更宽。在我的例子中，我需要文本符合指定的宽度。

这一更改使它调整大小，直到文本垂直和水平都适合。

在resizeText(int,int)中更改为:

// Get the required text height
int textHeight = getTextHeight(text, textPaint, width, targetTextSize);

// Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes
while(textHeight > height && targetTextSize > mMinTextSize) {
    targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
    textHeight = getTextHeight(text, textPaint, width, targetTextSize);
    }

to:

// Get the required text height
int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
int textWidth  = getTextWidth(text, textPaint, width, targetTextSize);

// Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes
while(((textHeight >= height) || (textWidth >= width) ) && targetTextSize > mMinTextSize) {
    targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
    textHeight = getTextHeight(text, textPaint, width, targetTextSize);
    textWidth  = getTextWidth(text, textPaint, width, targetTextSize);
    }

然后，在文件的末尾追加getTextWidth()例程;它只是稍微修改了一下getTextHeight()。将它们组合成一个返回高度和宽度的例程可能会更有效。

// Set the text size of the text paint object and use a static layout to render text off screen before measuring
private int getTextWidth(CharSequence source, TextPaint paint, int width, float textSize) {
    // Update the text paint object
    paint.setTextSize(textSize);
    // Draw using a static layout
    StaticLayout layout = new StaticLayout(source, paint, width, Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
    layout.draw(sTextResizeCanvas);
    return layout.getWidth();
}  

变更2:修复Eclipse Android布局编辑器中的EmptyStackException

在相当模糊和非常精确的条件下，布局编辑器将无法显示布局的图形显示;它会在com.android.ide.eclipse.adt中抛出一个"EmptyStackException: null"异常。

所需的条件是: -创建一个AutoResizeTextView小部件 -为那个小部件创建一个样式 -指定样式中的文本项;不在小部件定义中

如:

res / layout / main。xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <com.ajw.DemoCrashInADT.AutoResizeTextView
        android:id="@+id/resizingText"
        style="@style/myTextStyle" />

</LinearLayout>

res /价值/ myStyles.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <style name="myTextStyle" parent="@android:style/Widget.TextView">
        <item name="android:layout_height">wrap_content</item>
        <item name="android:layout_width">fill_parent</item>
        <item name="android:text">some message</item>
    </style>

</resources>

使用这些文件，在编辑main.xml时选择图形布局选项卡将显示:

错误! EmptyStackException:零 “> Show View > Error Log”记录异常详细信息

而不是布局的图形视图。

为了让已经太长的故事变得更短，我追踪到以下几行(同样是在resizeText中):

// If there is a max text size set, use the lesser of that and the default text size
float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize;

问题是，在特定的条件下，mTextSize从未初始化;它的值是0。

通过上述操作，targetTextSize被设置为零(这是Math.min的结果)。

这个零被传递给getTextHeight()(和getTextWidth())作为textSize参数。当它到达 layout.draw (sTextResizeCanvas); 我们得到了异常。

在resizeText()的开始测试if (mTextSize == 0)比在getTextHeight()和getTextWidth()测试更有效;更早地测试可以节省所有的中间工作。

通过这些更新，文件(就像在我的崩溃演示测试应用程序中一样)现在是:

//
// from:  http://stackoverflow.com/questions/5033012/auto-scale-textview-text-to-fit-within-bounds
//
//

package com.ajw.DemoCrashInADT;

import android.content.Context;
import android.graphics.Canvas;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;

/**
 * Text view that auto adjusts text size to fit within the view. If the text
 * size equals the minimum text size and still does not fit, append with an
 * ellipsis.
 *
 * 2011-10-29 changes by Alan Jay Weiner
 *              * change to fit both vertically and horizontally  
 *              * test mTextSize for 0 in resizeText() to fix exception in Layout Editor
 *
 * @author Chase Colburn
 * @since Apr 4, 2011
 */
public class AutoResizeTextView extends TextView {

    // Minimum text size for this text view
    public static final float MIN_TEXT_SIZE = 20;

    // Interface for resize notifications
    public interface OnTextResizeListener {
        public void onTextResize(TextView textView, float oldSize, float newSize);
    }

    // Off screen canvas for text size rendering
    private static final Canvas sTextResizeCanvas = new Canvas();

    // Our ellipse string
    private static final String mEllipsis = "...";

    // Registered resize listener
    private OnTextResizeListener mTextResizeListener;

    // Flag for text and/or size changes to force a resize
    private boolean mNeedsResize = false;

    // Text size that is set from code. This acts as a starting point for
    // resizing
    private float mTextSize;

    // Temporary upper bounds on the starting text size
    private float mMaxTextSize = 0;

    // Lower bounds for text size
    private float mMinTextSize = MIN_TEXT_SIZE;

    // Text view line spacing multiplier
    private float mSpacingMult = 1.0f;

    // Text view additional line spacing
    private float mSpacingAdd = 0.0f;

    // Add ellipsis to text that overflows at the smallest text size
    private boolean mAddEllipsis = true;


    // Default constructor override
    public AutoResizeTextView(Context context) {
        this(context, null);
    }


    // Default constructor when inflating from XML file
    public AutoResizeTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }


    // Default constructor override
    public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mTextSize = getTextSize();
    }


    /**
     * When text changes, set the force resize flag to true and reset the text
     * size.
     */
    @Override
    protected void onTextChanged(final CharSequence text, final int start,
            final int before, final int after) {
        mNeedsResize = true;
        // Since this view may be reused, it is good to reset the text size
        resetTextSize();
    }


    /**
     * If the text view size changed, set the force resize flag to true
     */
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        if (w != oldw || h != oldh) {
            mNeedsResize = true;
        }
    }


    /**
     * Register listener to receive resize notifications
     *
     * @param listener
     */
    public void setOnResizeListener(OnTextResizeListener listener) {
        mTextResizeListener = listener;
    }


    /**
     * Override the set text size to update our internal reference values
     */
    @Override
    public void setTextSize(float size) {
        super.setTextSize(size);
        mTextSize = getTextSize();
    }


    /**
     * Override the set text size to update our internal reference values
     */
    @Override
    public void setTextSize(int unit, float size) {
        super.setTextSize(unit, size);
        mTextSize = getTextSize();
    }


    /**
     * Override the set line spacing to update our internal reference values
     */
    @Override
    public void setLineSpacing(float add, float mult) {
        super.setLineSpacing(add, mult);
        mSpacingMult = mult;
        mSpacingAdd = add;
    }


    /**
     * Set the upper text size limit and invalidate the view
     *
     * @param maxTextSize
     */
    public void setMaxTextSize(float maxTextSize) {
        mMaxTextSize = maxTextSize;
        requestLayout();
        invalidate();
    }


    /**
     * Return upper text size limit
     *
     * @return
     */
    public float getMaxTextSize() {
        return mMaxTextSize;
    }


    /**
     * Set the lower text size limit and invalidate the view
     *
     * @param minTextSize
     */
    public void setMinTextSize(float minTextSize) {
        mMinTextSize = minTextSize;
        requestLayout();
        invalidate();
    }


    /**
     * Return lower text size limit
     *
     * @return
     */
    public float getMinTextSize() {
        return mMinTextSize;
    }


    /**
     * Set flag to add ellipsis to text that overflows at the smallest text size
     *
     * @param addEllipsis
     */
    public void setAddEllipsis(boolean addEllipsis) {
        mAddEllipsis = addEllipsis;
    }


    /**
     * Return flag to add ellipsis to text that overflows at the smallest text
     * size
     *
     * @return
     */
    public boolean getAddEllipsis() {
        return mAddEllipsis;
    }


    /**
     * Reset the text to the original size
     */
    public void resetTextSize() {
        super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
        mMaxTextSize = mTextSize;
    }


    /**
     * Resize text after measuring
     */
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        if (changed || mNeedsResize) {
            int widthLimit = (right - left) - getCompoundPaddingLeft()
                    - getCompoundPaddingRight();
            int heightLimit = (bottom - top) - getCompoundPaddingBottom()
                    - getCompoundPaddingTop();
            resizeText(widthLimit, heightLimit);
        }
        super.onLayout(changed, left, top, right, bottom);
    }


    /**
     * Resize the text size with default width and height
     */
    public void resizeText() {
        int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop();
        int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight();
        resizeText(widthLimit, heightLimit);
    }


    /**
     * Resize the text size with specified width and height
     *
     * @param width
     * @param height
     */
    public void resizeText(int width, int height) {
        CharSequence text = getText();
        // Do not resize if the view does not have dimensions or there is no
        // text
        // or if mTextSize has not been initialized
        if (text == null || text.length() == 0 || height <= 0 || width <= 0
                || mTextSize == 0) {
            return;
        }

        // Get the text view's paint object
        TextPaint textPaint = getPaint();

        // Store the current text size
        float oldTextSize = textPaint.getTextSize();

        // If there is a max text size set, use the lesser of that and the
        // default text size
        float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize)
                : mTextSize;

        // Get the required text height
        int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
        int textWidth = getTextWidth(text, textPaint, width, targetTextSize);

        // Until we either fit within our text view or we had reached our min
        // text size, incrementally try smaller sizes
        while (((textHeight > height) || (textWidth > width))
                && targetTextSize > mMinTextSize) {
            targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
            textHeight = getTextHeight(text, textPaint, width, targetTextSize);
            textWidth = getTextWidth(text, textPaint, width, targetTextSize);
        }

        // If we had reached our minimum text size and still don't fit, append
        // an ellipsis
        if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) {
            // Draw using a static layout
            StaticLayout layout = new StaticLayout(text, textPaint, width,
                    Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false);
            layout.draw(sTextResizeCanvas);
            int lastLine = layout.getLineForVertical(height) - 1;
            int start = layout.getLineStart(lastLine);
            int end = layout.getLineEnd(lastLine);
            float lineWidth = layout.getLineWidth(lastLine);
            float ellipseWidth = textPaint.measureText(mEllipsis);

            // Trim characters off until we have enough room to draw the
            // ellipsis
            while (width < lineWidth + ellipseWidth) {
                lineWidth = textPaint.measureText(text.subSequence(start, --end + 1)
                        .toString());
            }
            setText(text.subSequence(0, end) + mEllipsis);

        }

        // Some devices try to auto adjust line spacing, so force default line
        // spacing
        // and invalidate the layout as a side effect
        textPaint.setTextSize(targetTextSize);
        setLineSpacing(mSpacingAdd, mSpacingMult);

        // Notify the listener if registered
        if (mTextResizeListener != null) {
            mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize);
        }

        // Reset force resize flag
        mNeedsResize = false;
    }


    // Set the text size of the text paint object and use a static layout to
    // render text off screen before measuring
    private int getTextHeight(CharSequence source, TextPaint paint, int width,
            float textSize) {
        // Update the text paint object
        paint.setTextSize(textSize);
        // Draw using a static layout
        StaticLayout layout = new StaticLayout(source, paint, width,
                Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        layout.draw(sTextResizeCanvas);
        return layout.getHeight();
    }


    // Set the text size of the text paint object and use a static layout to
    // render text off screen before measuring
    private int getTextWidth(CharSequence source, TextPaint paint, int width,
            float textSize) {
        // Update the text paint object
        paint.setTextSize(textSize);
        // Draw using a static layout
        StaticLayout layout = new StaticLayout(source, paint, width,
                Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        layout.draw(sTextResizeCanvas);
        return layout.getWidth();
    }

}

非常感谢Chase发布了初始代码。我很喜欢通读它，看看它是如何工作的，我很高兴能够添加它。

我已经使用代码从追逐和M-WaJeEh 我发现了一些优点和缺点

从追逐

优势: 这是完美的1行TextView 劣势: 如果它超过1行自定义字体，一些文本将消失 如果它是使能椭圆，它没有为椭圆准备空间 如果是自定义字体(字体)，则不支持

从M-WaJeEh

优势: 非常适合多线使用 劣势: 如果将height设置为wrap-content，这段代码将从最小大小开始，并尽可能减小到最小，而不是从setSize开始并减小有限的宽度 如果是自定义字体(字体)，则不支持

警告，Android蜂巢和冰淇淋三明治有bug

android版本:3.1 - 4.04有一个错误，setTextSize()内部的TextView只工作第一次(第一次调用)。

Bug描述如下:http://code.google.com/p/android/issues/detail?id=22493 http://code.google.com/p/android/issues/detail?id=17343#c9

解决方法是添加新的行字符文本分配给TextView之前改变大小:

final String DOUBLE_BYTE_SPACE = "\u3000";
textView.append(DOUBLE_BYTE_SPACE);

我在我的代码中使用它如下:

final String DOUBLE_BYTE_SPACE = "\u3000";
AutoResizeTextView textView = (AutoResizeTextView) view.findViewById(R.id.aTextView);
String fixString = "";
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.HONEYCOMB_MR1
   && android.os.Build.VERSION.SDK_INT <= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {  
    fixString = DOUBLE_BYTE_SPACE;
}
textView.setText(fixString + "The text" + fixString);

我将这个“\u3000”字符添加到文本的左侧和右侧，以保持文本居中。如果你把它对齐到左边，那么只追加到右边。当然，它也可以嵌入到AutoResizeTextView小部件中，但我希望将修复代码保留在外部。