tlfTextField - Highlight a part of text with "Code" - actionscript-3

Question

I wonder how to set the text "Highlight" of a part of text inside tlfTextField with the code?
I tried "tf.backgroundColor = 0x990000" property, but did not help.
For instance, I can change the Font Color of any contents inside Parenthesis, by this code:
private function decorate():void {
var tf:TextFormat = new TextFormat();
tf.color = 0x990000;
var startPoint:int = 0;
while (startPoint != -1) {
var n1:int = textMc.tlfText.text.indexOf("(", startPoint);
var n2:int = textMc.tlfText.text.indexOf(")", n1 + 1);
if (n1 == -1 || n2 == -1) {
return;
}
textMc.tlfText.setTextFormat(tf, n1 + 1, n2);
startPoint = n2 + 1;
}
}
So I know "tf.color = 0x990000;" will change the Font color, however, don't know how to "highlight" some text, with code, as I do inside Flash manually.

Answer 1

You should have probably used tlfMarkup property to set the required format to the specific part of text. The attributes you seek are backgroundColor and backgroundAlpha of the span XML element that you should wrap your selection, however it should be much more difficult should there already be spans around words when you retrieve the property from your text field.
The problem with your solution is that you don't check if the two characters are located on a single line before drawing your rectangle, also you would need to redraw such rectangles each time something happens with the textfield. The proposed approach makes use of Flash HTML renderer's capabilities to preserve the formatting, however it will require a lot of work to handle this task properly.