Android SpannableString 在部分文本后面设置背景

Question

我想创建与此图片类似的东西:

我设法用 SpannableStringBuilder 创建了evertyhing，橙色圆角矩形除外。我可以使用 BackgroundColorSpan 将背景设置为该颜色，但我找不到使它变圆的方法。有什么想法可以实现吗？

提前致谢!

编辑: 我正在使用 Xamarin.Android，但这是我的代码:

stringBuilder.SetSpan(new BackgroundColorSpan(Application.Context.Resources.GetColor(Resource.Color.orangeColor)), stringBuilder.Length() - length, stringBuilder.Length(), SpanTypes.ExclusiveExclusive);

Answer 1

如果有人对 Roosevelt 的代码示例有疑问(我确定是，可能是因为它是 Xamarin.Android？)，这里是一个更基本的 Android java 版本的翻译:

    public class RoundedBackgroundSpan extends ReplacementSpan {

        private static int CORNER_RADIUS = 8;
        private int backgroundColor = 0;
        private int textColor = 0;

        public RoundedBackgroundSpan(Context context) {
            super();
            backgroundColor = context.getResources().getColor(R.color.gray);
            textColor = context.getResources().getColor(R.color.white);
        }

        @Override
        public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, Paint paint) {
            RectF rect = new RectF(x, top, x + measureText(paint, text, start, end), bottom);
            paint.setColor(backgroundColor);
            canvas.drawRoundRect(rect, CORNER_RADIUS, CORNER_RADIUS, paint);
            paint.setColor(textColor);
            canvas.drawText(text, start, end, x, y, paint);
        }

        @Override
        public int getSize(Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
            return Math.round(paint.measureText(text, start, end));
        }

        private float measureText(Paint paint, CharSequence text, int start, int end) {
            return paint.measureText(text, start, end);
        }
    }

为了使用，下面的代码段取自一个 Activity ，基本上在每个标签字符串周围放置了一个漂亮的圆角背景，每个标签之间有一个空间缓冲区。请注意，注释掉的行只是添加了背景颜色，不会产生很好的外观...

    SpannableStringBuilder stringBuilder = new SpannableStringBuilder();

    String between = "";
    for (String tag : eventListing.getTags()) {
       stringBuilder.append(between);
       if (between.length() == 0) between = "  ";
       String thisTag = "  "+tag+"  ";
       stringBuilder.append(thisTag);
       stringBuilder.setSpan(new RoundedBackgroundSpan(this), stringBuilder.length() - thisTag.length(), stringBuilder.length() - thisTag.length() + thisTag.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
       //stringBuilder.setSpan(new BackgroundColorSpan(getResources().getColor(R.color.gray)), stringBuilder.length() - thisTag.length(), stringBuilder.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    }

    TextView tv = new TextView(this);
    tv.setText(stringBuilder);