Canvas drawText实现中英文居中

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

            Paint mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            // Measure a text
            Rect textBounds = new Rect();
            mTextPaint.getTextBounds(String.valueOf(mLetter), 0, 1, textBounds);
            float textWidth = mTextPaint.measureText(String.valueOf(mLetter));
            float textHeight = textBounds.height();

            FontMetrics fontMetrics = mTextPaint.getFontMetrics();
            // 计算文字高度
            float fontHeight = fontMetrics.bottom - fontMetrics.top;
            // 计算文字baseline
            float textBaseY = getHeight() - (getHeight() - fontHeight) / 2
                    - fontMetrics.bottom;

            // Draw the text
            canvas.drawText(String.valueOf(mLetter), getWidth() / 2f
                    - textWidth / 2f, textBaseY, mTextPaint);
    }