Check if font is embedded? - actionscript-3

Question

Can I check if I'm using an actual font when I create TextFormat/TextField ? If I specify a not embedded font or use any random string, no text is displayed and I don't know why.
import flash.display.Sprite;
import flash.text.TextField;
import flash.text.TextFieldAutoSize;
import flash.text.TextFormat;
public class SimpleSprite extends Sprite
{
//[Embed(source="C:/Windows/Fonts/Arial.ttf",fontName="default_font",mimeType="application/x-font",fontWeight="normal",fontStyle="normal",advancedAntiAliasing="true",embedAsCFF="false")]
//private static var defaultFont: String;
public function SimpleSprite()
{
var t: TextField = new TextField;
t.autoSize = TextFieldAutoSize.LEFT;
t.defaultTextFormat = new TextFormat("default_font", 16, 0xff0000);
t.embedFonts = true;
t.text = "hello world";
addChild(t);
}
}
It doesn't display any text when the embed lines are missing.
Important: My package that creates TextFields does not embed anything and I wish to keep it that way. The embedding must be done by the programmer who uses the package. I want to check if the font is embedded and throw an error if not.

Answer 1

You can use Font.enumerateFonts which will return an array of available embedded fonts. You could use that to create a function like the following:
private function hasEmbeddedFont(fontName:String):Boolean
{
var fonts:Array = Font.enumerateFonts();
for each(var font:Font in fonts)
{
if (font.fontName == fontName)
{
return true;
}
}
return false;
}
And then use it something like this:
t.autoSize = TextFieldAutoSize.LEFT;
t.defaultTextFormat = new TextFormat("default_font", 16, 0xff0000);
t.embedFonts = hasEmbeddedFont("default_font");
t.text = "hello world";
If you're building a library for others to use, you might consider abstracting it into your own custom subclass of TextField so it's all handled automatically.