如果有人对罗斯福的代码示例感到困难(我确信是这样,也许是因为它是Xamarin.Android?),那么这里有一个更基本的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);
}
}
关于用法,下面的代码段来自一个Activity,基本上是在每个标签字符串周围放置了一个漂亮的圆角背景,并在每个标签之间加入了一个特殊缓冲区。请注意,被注释的行仅仅添加了一个背景颜色,这样做不会产生很好看的效果...
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);
}
TextView tv = new TextView(this);
tv.setText(stringBuilder);