Android SpannableString在部分文字后面设置背景

Android SpannableString在部分文字后面设置背景

如果有人在处理罗斯福的代码示例时遇到困难（我肯定是，也许是因为它是Xamarin.Android？），这是一个更基本的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);        }    }

为了便于使用，以下代码段取自Activity，基本上在每个标签字符串周围放置了一个圆角背景，每个标签之间都有一个空格缓冲区。请注意，注释掉的行仅带有背景色，看起来效果不佳。

    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);