android - Styling notification InboxStyle

Question

I try to implement an extendable notification and I have used the InboxStyle for that.

Based on the following image from the documentation:

it should be possible to style the text. In this case make "Google Play" bold.

InboxStyle has only addLine() where I can pass a CharSequence. I tried with Html.fromHtml() and used some html formatting but I couldn't succeed.

NotificationCompat.InboxStyle inboxStyle = new NotificationCompat.InboxStyle();
inboxStyle.setBigContentTitle("title");
inboxStyle.setSummaryText("summarytext");
// fetch push messages
synchronized (mPushMessages) {
    HashMap<String, PushMessage> messages = mPushMessages.get(key);
    if (messages != null) {
        for (Entry<String, PushMessage> msg : messages.entrySet()) {
            inboxStyle.addLine(Html.fromHtml("at least <b>one word</b> should be bold!");
        }
        builder.setStyle(inboxStyle);
        builder.setNumber(messages.size());
    }
}

Any idea about this?

Answer 1

You don't need to use fromHtml. I've had issues with fromHtml in the past (when what you display comes from user, code injection can result in ugly things). Also, I don't like putting formatting elements in strings.xml (if you use services for translation, they might screw up your HTML tags).

The addLine method, as most methods to set text in notifications (setTicker, setContentInfo, setContentTitle, etc.) take a CharSequence as parameter.

So you can pass a Spannable. Let's say you want "Bold this and italic that.", you can format it this way (of course don't hardcode positions):

Spannable sb = new SpannableString("Bold this and italic that.");
sb.setSpan(new StyleSpan(android.graphics.Typeface.BOLD), 0, 4, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
sb.setSpan(new StyleSpan(android.graphics.Typeface.ITALIC), 14, 20, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
inboxStyle.addLine(sb);

Now if you need to build string dynamically with localized strings, like "Today is [DAY], good morning!", put string with a placeholder in strings.xml:

<string name="notification_line_format">Today is %1$s, good morning!</string>

Then format this way:

String today = "Sunday";
String lineFormat = context.getString(R.string.notification_line_format);
int lineParamStartPos = lineFormat.indexOf("%1$s");
if (lineParamStartPos < 0) {
  throw new InvalidParameterException("Something's wrong with your string! LINT could have caught that.");
}
String lineFormatted = context.getString(R.string.notification_line_format, today);

Spannable sb = new SpannableString(lineFormatted);
sb.setSpan(new StyleSpan(android.graphics.Typeface.BOLD), lineParamStartPos, lineParamStartPos + today.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
inboxStyle.addLine(sb);

You'll get "Today is Sunday, good morning!", and as far as I know it works with all versions of Android.