如何在Android中使用另一种颜色获得UnderlineSpan？

Question

我希望在IDE中看起来像错误的Spannable - 用另一种颜色加下划线.

我试图创建ColorUnderlineSpan扩展android的类UnderlineSpan,但它使所有文本成为另一种颜色(我只需要添加彩色下划线):

/**
 * Underline Span with color
 */
public class ColorUnderlineSpan extends android.text.style.UnderlineSpan {

    private int underlineColor;

    public ColorUnderlineSpan(int underlineColor) {
        super();
        this.underlineColor = underlineColor;
    }

    @Override
    public void updateDrawState(TextPaint ds) {
        super.updateDrawState(ds);
        ds.setColor(underlineColor);
    }
}

我也找到了DynamicDrawableSpan课程,但我看不到画布边界要画.

使用带有bounds参数的抽象绘制方法获得任何Spannable impl会很棒.

Answer 1

这不是最漂亮的解决方案,但它最终为我工作:

public class CustomUnderlineSpan implements LineBackgroundSpan {

int color;
Paint p;
int start, end;
public CustomUnderlineSpan(int underlineColor, int underlineStart, int underlineEnd) {
    super();
    color = underlineColor;
    this.start = underlineStart;
    this.end = underlineEnd;
    p = new Paint();
    p.setColor(color);
    p.setStrokeWidth(3F);
    p.setStyle(Paint.Style.FILL_AND_STROKE);
}

@Override
public void drawBackground(Canvas c, Paint p, int left, int right, int top, int baseline, int bottom, CharSequence text, int start, int end, int lnum) {

    if (this.end < start) return;
    if (this.start > end) return;

    int offsetX = 0;
    if (this.start > start) {
        offsetX = (int)p.measureText(text.subSequence(start, this.start).toString());
    }

    int length = (int)p.measureText(text.subSequence(Math.max(start, this.start), Math.min(end, this.end)).toString());
    c.drawLine(offsetX, baseline + 3F, length + offsetX, baseline + 3F, this.p);
}

这很奇怪,因为你必须指定字符索引来开始和结束你的下划线,但它对我有用.