Android TextView:如何将文本放在行中的特定位置上方/设置ReplacementScan子类的高度

我正试图在TextView中用和弦显示歌词.为此,我需要在正文的特定部分上方放置字母或符号.到目前为止,我的想法是将ReplacementSpan子类化为:

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.FontMetricsInt;
import android.text.style.ReplacementSpan;

public class ChordSpan extends ReplacementSpan {

    String chord;

    public ChordSpan(String chord) {
        super();

        this.chord = chord;
    }

    @Override
    public void draw(Canvas canvas,
        CharSequence text, int start, int end,
        float x, int top, int y, int bottom,
        Paint paint) {

        FontMetricsInt fm = paint.getFontMetricsInt();
        int space = fm.ascent-fm.descent+fm.leading;

        canvas.drawText(text, start, end, x, y, paint);
        canvas.drawText(chord, x, y+space, paint);
    }

    @Override
    public int getSize(Paint paint, CharSequence text, int start, int end,
        FontMetricsInt fm) {

        return Math.round(paint.measureText(text, start, end));
    }

}

这可以很好地将和弦符号放在文本上方.但是,当我添加和弦时,我还没有找到一种调整行高的方法,因此和弦会在TextView中的前一行中被绘制.这段代码演示了我的意思:

package com.example.chordspan;

import android.os.Bundle;
import android.app.Activity;
import android.text.Spannable;
import android.text.SpannableStringBuilder;
import android.view.Gravity;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        TextView tv = new TextView(this.getBaseContext());
        tv.setGravity(Gravity.CENTER_VERTICAL);

        SpannableStringBuilder sb = new SpannableStringBuilder();

        sb.append("The line above\n");

        int start = sb.length();
        sb.append("A line with chords\n");
        sb.setSpan(new ChordSpan("C"), start, start+2,
            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        sb.setSpan(new ChordSpan("Am"), start+7, start+11,
            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

        sb.append("The line below");

        tv.setText(sb);

        setContentView(tv);
    }
}

您将看到和弦已对齐并正确绘制,但与"上面的线"重叠.

有没有办法实现我想要的,即在绘制我的自定义跨度时以某种方式调整线条的线条高度？我还没有找到任何有关ReplacementSpan子类的好例子.

或者,我很乐意收到有关如何达到预期效果的其他建议.也许我正在思考一个完全错误的方向.

感谢您阅读到目前为止,并提供任何帮助!