android.text.TextPaint#setLetterSpacing ( )源码实例Demo

private static float getLetterSpacing(CharSequence text, TextPaint paint, float targetWidth,
                                      float low, float high, float precision) {
    float mid = (low + high) / 2.0f;
    paint.setLetterSpacing(mid);

    float measuredWidth = paint.measureText(text, 0, text.length());

    if (high - low < precision) {
        if (measuredWidth < targetWidth) {
            return mid;
        } else {
            return low;
        }
    } else if (measuredWidth > targetWidth) {
        return getLetterSpacing(text, paint, targetWidth, low, mid, precision);
    } else if (measuredWidth < targetWidth) {
        return getLetterSpacing(text, paint, targetWidth, mid, high, precision);
    } else {
        return mid;
    }
}
 

private void apply(TextPaint paint) {
  // mLetterSpacing and paint.getTextSize() are both in pixels,
  // yielding an accurate em value.
  if (!Float.isNaN(mLetterSpacing)) {
    paint.setLetterSpacing(mLetterSpacing / paint.getTextSize());
  }
}
 

private Layout createLayout(ReflowData data, Context context, boolean enforceMaxLines) {
    TextPaint paint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
    paint.setTextSize(data.textSize);
    paint.setColor(data.textColor);
    paint.setLetterSpacing(data.letterSpacing);
    if (data.fontName != null) {
        paint.setTypeface(FontUtil.get(context, data.fontName));
    }

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        StaticLayout.Builder builder =  StaticLayout.Builder.obtain(
                data.text, 0, data.text.length(), paint, data.textWidth)
                .setLineSpacing(data.lineSpacingAdd, data.lineSpacingMult)
                .setBreakStrategy(data.breakStrategy);
        if (enforceMaxLines && data.maxLines != -1) {
            builder.setMaxLines(data.maxLines);
            builder.setEllipsize(TextUtils.TruncateAt.END);
        }
        return builder.build();
    } else {
        return new StaticLayout(
                data.text,
                paint,
                data.textWidth,
                Layout.Alignment.ALIGN_NORMAL,
                data.lineSpacingMult,
                data.lineSpacingAdd,
                true);
    }
}
 

private void apply(TextPaint paint) {
    paint.setLetterSpacing(mLetterSpacing / paint.getTextSize());
}
 

/**
 * 初始化画笔
 */
private void initPaint() {
    Typeface typeface;
    try {
        if (!TextUtils.isEmpty(readBookControl.getFontPath())) {
            typeface = Typeface.createFromFile(readBookControl.getFontPath());
        } else {
            typeface = Typeface.SANS_SERIF;
        }
    } catch (Exception e) {
        Toast.makeText(mContext, "字体文件未找,到恢复默认字体", Toast.LENGTH_SHORT).show();
        readBookControl.setReadBookFont(null);
        typeface = Typeface.SANS_SERIF;
    }
    // 绘制提示的画笔
    mTipPaint = new TextPaint();
    mTipPaint.setColor(readBookControl.getTextColor());
    mTipPaint.setTextAlign(Paint.Align.LEFT); // 绘制的起始点
    mTipPaint.setTextSize(ScreenUtils.spToPx(DEFAULT_TIP_SIZE)); // Tip默认的字体大小
    mTipPaint.setTypeface(Typeface.create(typeface, Typeface.NORMAL));
    mTipPaint.setAntiAlias(true);
    mTipPaint.setSubpixelText(true);

    // 绘制标题的画笔
    mTitlePaint = new TextPaint();
    mTitlePaint.setColor(readBookControl.getTextColor());
    mTitlePaint.setTextSize(mTitleSize);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        mTitlePaint.setLetterSpacing(readBookControl.getTextLetterSpacing());
    }
    mTitlePaint.setStyle(Paint.Style.FILL_AND_STROKE);
    mTitlePaint.setTypeface(Typeface.create(typeface, Typeface.BOLD));
    mTitlePaint.setTextAlign(Paint.Align.CENTER);
    mTitlePaint.setAntiAlias(true);

    // 绘制页面内容的画笔
    mTextPaint = new TextPaint();
    mTextPaint.setColor(readBookControl.getTextColor());
    mTextPaint.setTextSize(mTextSize);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        mTextPaint.setLetterSpacing(readBookControl.getTextLetterSpacing());
    }
    int bold = readBookControl.getTextBold() ? Typeface.BOLD : Typeface.NORMAL;
    mTextPaint.setTypeface(Typeface.create(typeface, bold));
    mTextPaint.setAntiAlias(true);

    // 绘制结束的画笔
    mTextEndPaint = new TextPaint();
    mTextEndPaint.setColor(readBookControl.getTextColor());
    mTextEndPaint.setTextSize(mTextEndSize);
    mTextEndPaint.setTypeface(Typeface.create(typeface, Typeface.NORMAL));
    mTextEndPaint.setAntiAlias(true);
    mTextEndPaint.setSubpixelText(true);
    mTextEndPaint.setTextAlign(Paint.Align.CENTER);

    // 绘制电池的画笔
    mBatteryPaint = new TextPaint();
    mBatteryPaint.setAntiAlias(true);
    mBatteryPaint.setDither(true);
    mBatteryPaint.setTextSize(ScreenUtils.spToPx(DEFAULT_TIP_SIZE - 3));
    mBatteryPaint.setTypeface(Typeface.createFromAsset(mContext.getAssets(), "number.ttf"));

    setupTextInterval();
    // 初始化页面样式
    initPageStyle();
}