我刚刚创建了以下方法(基于Chase的想法)，如果你想在任何画布上绘制文本，它可能会帮助你:

private static void drawText(Canvas canvas, int xStart, int yStart,
        int xWidth, int yHeigth, String textToDisplay,
        TextPaint paintToUse, float startTextSizeInPixels,
        float stepSizeForTextSizeSteps) {

    // Text view line spacing multiplier
    float mSpacingMult = 1.0f;
    // Text view additional line spacing
    float mSpacingAdd = 0.0f;
    StaticLayout l = null;
    do {
        paintToUse.setTextSize(startTextSizeInPixels);
        startTextSizeInPixels -= stepSizeForTextSizeSteps;
        l = new StaticLayout(textToDisplay, paintToUse, xWidth,
                Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
    } while (l.getHeight() > yHeigth);

    int textCenterX = xStart + (xWidth / 2);
    int textCenterY = (yHeigth - l.getHeight()) / 2;

    canvas.save();
    canvas.translate(textCenterX, textCenterY);
    l.draw(canvas);
    canvas.restore();
}

这可以在任何自定义视图的任何onDraw()方法中使用。

实际上解决方案是在谷歌的DialogTitle类…虽然它不如公认的方法有效，但它更简单，也更容易适应。

public class SingleLineTextView extends TextView {

  public SingleLineTextView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    setSingleLine();
    setEllipsize(TruncateAt.END);
  }

  public SingleLineTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
    setSingleLine();
    setEllipsize(TruncateAt.END);
  }

  public SingleLineTextView(Context context) {
    super(context);
    setSingleLine();
    setEllipsize(TruncateAt.END);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    final Layout layout = getLayout();
    if (layout != null) {
      final int lineCount = layout.getLineCount();
      if (lineCount > 0) {
        final int ellipsisCount = layout.getEllipsisCount(lineCount - 1);
        if (ellipsisCount > 0) {

          final float textSize = getTextSize();

          // textSize is already expressed in pixels
          setTextSize(TypedValue.COMPLEX_UNIT_PX, (textSize - 1));

          super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
      }
    }
  }

}

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

更新:下面的代码也满足了一个理想的AutoScaleTextView的要求，如这里所述:自动适合Android的TextView，并被标记为赢家。

更新2:增加了对maxlines的支持，现在在API级别16之前工作正常。

更新3:支持android: drawablleft, android:drawableRight, android:drawableTop和android:drawableBottom标签添加，感谢MartinH在这里的简单修复。

我的要求有点不同。我需要一种有效的方法来调整大小，因为我是动画一个整数从，可能是0 ~4000在TextView在2秒内，我想相应地调整大小。我的解决方法有点不同。这是最终的结果:

以及产生它的代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp" >

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:ellipsize="none"
        android:maxLines="2"
        android:text="Auto Resized Text, max 2 lines"
        android:textSize="100sp" /> <!-- maximum size -->

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:ellipsize="none"
        android:gravity="center"
        android:maxLines="1"
        android:text="Auto Resized Text, max 1 line"
        android:textSize="100sp" /> <!-- maximum size -->

    <com.vj.widgets.AutoResizeTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Auto Resized Text"
        android:textSize="500sp" /> <!-- maximum size -->

</LinearLayout>

最后是java代码:

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.RectF;
import android.os.Build;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.SparseIntArray;
import android.util.TypedValue;
import android.widget.TextView;

public class AutoResizeTextView extends TextView {
private interface SizeTester {
    /**
     * 
     * @param suggestedSize
     *            Size of text to be tested
     * @param availableSpace
     *            available space in which text must fit
     * @return an integer < 0 if after applying {@code suggestedSize} to
     *         text, it takes less space than {@code availableSpace}, > 0
     *         otherwise
     */
    public int onTestSize(int suggestedSize, RectF availableSpace);
}

private RectF mTextRect = new RectF();

private RectF mAvailableSpaceRect;

private SparseIntArray mTextCachedSizes;

private TextPaint mPaint;

private float mMaxTextSize;

private float mSpacingMult = 1.0f;

private float mSpacingAdd = 0.0f;

private float mMinTextSize = 20;

private int mWidthLimit;

private static final int NO_LINE_LIMIT = -1;
private int mMaxLines;

private boolean mEnableSizeCache = true;
private boolean mInitiallized;

public AutoResizeTextView(Context context) {
    super(context);
    initialize();
}

public AutoResizeTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initialize();
}

public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    initialize();
}

private void initialize() {
    mPaint = new TextPaint(getPaint());
    mMaxTextSize = getTextSize();
    mAvailableSpaceRect = new RectF();
    mTextCachedSizes = new SparseIntArray();
    if (mMaxLines == 0) {
        // no value was assigned during construction
        mMaxLines = NO_LINE_LIMIT;
    }
    mInitiallized = true;
}

@Override
public void setText(final CharSequence text, BufferType type) {
    super.setText(text, type);
    adjustTextSize(text.toString());
}

@Override
public void setTextSize(float size) {
    mMaxTextSize = size;
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

@Override
public void setMaxLines(int maxlines) {
    super.setMaxLines(maxlines);
    mMaxLines = maxlines;
    reAdjust();
}

public int getMaxLines() {
    return mMaxLines;
}

@Override
public void setSingleLine() {
    super.setSingleLine();
    mMaxLines = 1;
    reAdjust();
}

@Override
public void setSingleLine(boolean singleLine) {
    super.setSingleLine(singleLine);
    if (singleLine) {
        mMaxLines = 1;
    } else {
        mMaxLines = NO_LINE_LIMIT;
    }
    reAdjust();
}

@Override
public void setLines(int lines) {
    super.setLines(lines);
    mMaxLines = lines;
    reAdjust();
}

@Override
public void setTextSize(int unit, float size) {
    Context c = getContext();
    Resources r;

    if (c == null)
        r = Resources.getSystem();
    else
        r = c.getResources();
    mMaxTextSize = TypedValue.applyDimension(unit, size,
            r.getDisplayMetrics());
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

@Override
public void setLineSpacing(float add, float mult) {
    super.setLineSpacing(add, mult);
    mSpacingMult = mult;
    mSpacingAdd = add;
}

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

private void reAdjust() {
    adjustTextSize(getText().toString());
}

private void adjustTextSize(String string) {
    if (!mInitiallized) {
        return;
    }
    int startSize = (int) mMinTextSize;
    int heightLimit = getMeasuredHeight() - getCompoundPaddingBottom()
        - getCompoundPaddingTop();
    mWidthLimit = getMeasuredWidth() - getCompoundPaddingLeft()
        - getCompoundPaddingRight();
    mAvailableSpaceRect.right = mWidthLimit;
    mAvailableSpaceRect.bottom = heightLimit;
    super.setTextSize(
            TypedValue.COMPLEX_UNIT_PX,
            efficientTextSizeSearch(startSize, (int) mMaxTextSize,
                    mSizeTester, mAvailableSpaceRect));
}

private final SizeTester mSizeTester = new SizeTester() {
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    @Override
    public int onTestSize(int suggestedSize, RectF availableSPace) {
        mPaint.setTextSize(suggestedSize);
        String text = getText().toString();
        boolean singleline = getMaxLines() == 1;
        if (singleline) {
            mTextRect.bottom = mPaint.getFontSpacing();
            mTextRect.right = mPaint.measureText(text);
        } else {
            StaticLayout layout = new StaticLayout(text, mPaint,
                    mWidthLimit, Alignment.ALIGN_NORMAL, mSpacingMult,
                    mSpacingAdd, true);
            // return early if we have more lines
            if (getMaxLines() != NO_LINE_LIMIT
                    && layout.getLineCount() > getMaxLines()) {
                return 1;
            }
            mTextRect.bottom = layout.getHeight();
            int maxWidth = -1;
            for (int i = 0; i < layout.getLineCount(); i++) {
                if (maxWidth < layout.getLineWidth(i)) {
                    maxWidth = (int) layout.getLineWidth(i);
                }
            }
            mTextRect.right = maxWidth;
        }

        mTextRect.offsetTo(0, 0);
        if (availableSPace.contains(mTextRect)) {
            // may be too small, don't worry we will find the best match
            return -1;
        } else {
            // too big
            return 1;
        }
    }
};

/**
 * Enables or disables size caching, enabling it will improve performance
 * where you are animating a value inside TextView. This stores the font
 * size against getText().length() Be careful though while enabling it as 0
 * takes more space than 1 on some fonts and so on.
 * 
 * @param enable
 *            enable font size caching
 */
public void enableSizeCache(boolean enable) {
    mEnableSizeCache = enable;
    mTextCachedSizes.clear();
    adjustTextSize(getText().toString());
}

private int efficientTextSizeSearch(int start, int end,
        SizeTester sizeTester, RectF availableSpace) {
    if (!mEnableSizeCache) {
        return binarySearch(start, end, sizeTester, availableSpace);
    }
    String text = getText().toString();
    int key = text == null ? 0 : text.length();
    int size = mTextCachedSizes.get(key);
    if (size != 0) {
        return size;
    }
    size = binarySearch(start, end, sizeTester, availableSpace);
    mTextCachedSizes.put(key, size);
    return size;
}

private static int binarySearch(int start, int end, SizeTester sizeTester,
        RectF availableSpace) {
    int lastBest = start;
    int lo = start;
    int hi = end - 1;
    int mid = 0;
    while (lo <= hi) {
        mid = (lo + hi) >>> 1;
        int midValCmp = sizeTester.onTestSize(mid, availableSpace);
        if (midValCmp < 0) {
            lastBest = lo;
            lo = mid + 1;
        } else if (midValCmp > 0) {
            hi = mid - 1;
            lastBest = hi;
        } else {
            return mid;
        }
    }
    // make sure to return last best
    // this is what should always be returned
    return lastBest;

}

@Override
protected void onTextChanged(final CharSequence text, final int start,
        final int before, final int after) {
    super.onTextChanged(text, start, before, after);
    reAdjust();
}

@Override
protected void onSizeChanged(int width, int height, int oldwidth,
        int oldheight) {
    mTextCachedSizes.clear();
    super.onSizeChanged(width, height, oldwidth, oldheight);
    if (width != oldwidth || height != oldheight) {
        reAdjust();
    }
}
}

我只是借用了一些其他人的想法，并在下面写了一些代码，可能会有帮助。

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

public class AutoResizeTextView extends TextView {
    private static final int MAX_SIZE = 1000;

    private static final int MIN_SIZE = 5;

    private TextPaint mTextPaint;

    private float mSpacingMult = 1.0f;

    private float mSpacingAdd = 0.0f;

    private boolean needAdapt = false;

    private boolean adapting = false;

    public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    public AutoResizeTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public AutoResizeTextView(Context context) {
        super(context);
        init();
    }

    private void init() {
        mTextPaint = new TextPaint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (adapting) {
            return;
        }
        if (needAdapt) {
            adaptTextSize();
        } else {
            super.onDraw(canvas);
        }
    }

    private void adaptTextSize() {
        CharSequence text = getText();
        int viewWidth = getMeasuredWidth();
        int viewHeight = getMeasuredHeight();

        if (viewWidth==0 || viewHeight==0
                || TextUtils.isEmpty(text)) {
            return;
        }

        adapting = true;
        /* binary search */
        int bottom=MIN_SIZE, top=MAX_SIZE, mid = 0;
        while (bottom <= top) {
            mid = (bottom + top)/2;
            mTextPaint.setTextSize(mid);
            int textWidth = (int) mTextPaint.measureText(text, 0, text.length());
            int textHeight = getTextHeight(text, viewWidth);
            if (textWidth<viewWidth && textHeight<viewHeight) {
                bottom = mid+1;
            } else {
                top = mid-1;
            }
        }

        int newSize = mid-1;
        setTextSize(TypedValue.COMPLEX_UNIT_PX, newSize);

        adapting=false;
        needAdapt = false;

        invalidate();
    }

    private int getTextHeight(CharSequence text, int targetWidth) {
        StaticLayout layout = new StaticLayout(text, mTextPaint, targetWidth,
                Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
        return layout.getHeight();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        needAdapt = true;
    }

    @Override
    protected void onTextChanged(CharSequence text, int start,
            int lengthBefore, int lengthAfter) {
        super.onTextChanged(text, start, lengthBefore, lengthAfter);
        needAdapt = true;
    }

    @Override
    public void setLineSpacing(float add, float mult) {
        super.setLineSpacing(add, mult);
        mSpacingMult = mult;
        mSpacingAdd = add;
    }
}

我的方法是:

public void changeTextSize(int initialSize, TextView tv) {

    DisplayMetrics displayMetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
    double width = displayMetrics.widthPixels / displayMetrics.xdpi;
    double height = displayMetrics.heightPixels / displayMetrics.ydpi;

    Log.i("LOG", "The width of the tested emulator is: " + width);
    Log.i("LOG", "The height of the tested emulator is: " + height);

    double scale = Math.min(width / 2.25, height / 4.0); //See the logcat >>> width = 2.25 and heigt = 4.0
    tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, (int) (initialSize * scale));

}

例如:

changeTextSize(16, findViewById(R.id.myTextView));
changeTextSize(12, findViewById(R.id.myEditText));