How do I deal with characters unsupported by the font file when using imagettftext()?

Question

I use Verdana font inside my images created by PHP GD library.

imagettftext($image, $fontSize, 0, 70, $y, $color, $font, $username );

Most of the cases imagettftext works very well for strings.
But some of my users use weird characters/symbols inside their names.
So when I try to print their names to images. For example:

This user uses ɦɪɲɣƙƨєʌɾ symbols. So Verdana can't print them.

I used this:

$username=iconv('UTF-8', 'ASCII//TRANSLIT', $username);

Output is this:

(Current locale changes between English and Deutsch. So maybe current locale can't handle these characters: ɦɪɲɣƙƨєʌɾ)

It seems like it's not possible to transliterate ɦ to h, ɲ to n without writing a very big str_replace() block. Like this.

• So I wonder whether is it possible to check whether the font (Verdana) can show these symbols. If one of the character can't be shown inside string, so I can pass an empty string to imagettftext method. Can I check the supported characters inside font ? Or create a character map that includes Verdana supported symbols, and check whether my string includes non-supported symbols ?
  (I think it is not possible due to this question)

• Or maybe another solution, is it possible to use multiple fonts in imagettftext() ?
  For example first try Verdana, if Verdana doesn't cover that symbols use Arial sans serif etc.

• Or any other solution ?

Edit:
It seems like Verdana doesn't support these unicode characters in my text.
Verdana supported characters: http://www.fileformat.info/info/unicode/font/verdana/grid.htm
Verdana unspported characters: http://www.fileformat.info/info/unicode/font/verdana/missing.htm

Answer 1

My first choice would be switching to a font that supports the full range of characters that you want to be able to handle. But do not expect a single font will ever implement the million-or-so possible characters in UTF-8.

Now, if you want to take the (lazy ;) transliteration route, I will refer to this answer from Kemal Dağ:

• PHP >= 5.4 : use the new built-in Transliterator class
• PHP < 5.4 : use his excellent port

I don't have a v5.4 on hand right now so I cannot tell about Transliterator, but Kemal Dağ's port of JTransliteration performs pretty well:

<?php
    require 'transliteration/JTransliteration.php';

    $input = 'ɦɪɲɣƙƨєʌɾ';
    echo JTransliteration::transliterate($input); // output: hIngk2ie^r

    $input = 'Хეλлఒ Wओრলद';
    echo JTransliteration::transliterate($input);

Finally, if you want to check wether a given font supports a given character, it gets a bit more hairy. This library will help a lot. It requires >= 5.3 (use of namespaces):

<?php
    $fontFile = 'arial.ttf';
    $charToCheck = 'ɣ';

    require_once 'php-font-lib-master/src/FontLib/Autoloader.php';

    use FontLib\Font;
    use FontLib\TrueType\Collection;


    $font = Font::load($fontFile);
    if ($font instanceof Collection) {
        $font = $font->getFont(0);
    }
    $subtable = null;
    foreach($font->getData("cmap", "subtables") as $_subtable) {
        if ($_subtable["platformID"] == 3 && $_subtable["platformSpecificID"] == 1) {
            $subtable = $_subtable;
            break;
        }
    }

    if (isset($subtable["glyphIndexArray"][ord_utf8($charToCheck)])) {
        $supported = 'Supported';
    } else {
        $supported = 'Not Supported';
    }

    echo "$charToCheck is $supported by font $fontFile";


    function ord_utf8($c) {
        $b0 = ord($c[0]);
        if ( $b0 < 0x10 ) {
            return $b0;
        }
        $b1 = ord($c[1]);
        if ( $b0 < 0xE0 ) {
            return (($b0 & 0x1F) << 6) + ($b1 & 0x3F);
        }
        return (($b0 & 0x0F) << 12) + (($b1 & 0x3F) << 6) + (ord($c[2]) & 0x3F);
    }

shamelessly pillaging code from font_info.php and R. Hill's ord_utf8()

P.S. The string "ɦɪɲɣƙƨєʌɾ" is made of characters from the International Phonetic Alphabet. I am not sure any locale supports these characters (since there is no practical need for it, as they are not used by any real human language).

Answer 2

As long as you're using UTF-8, there is no reason for UTF-8 True Type font to show those letters (disclaimer for east-asian letters!)

Here my simple example, with a true type font:

// utf-8 text
$text   = 'ɦɪɲɣƙƨєʌɾ';

// if text read from a file (for example)
// and the default locale (for most of western countries)
// is ISO-8859-1, you can simly convert it to
// utf-8 using:

//$text = utf8_encode($text);

$png    = imagecreatefrompng('/tmp/sample.png');
$color  = imagecolorallocate($png, 0, 0, 0);

// True type font that support UTF-8!!!!
$font   = '/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf';

imagettftext($png, 50, 0, 50, 50, $color, $font, $text);
imagepng($png, '/tmp/test.png');

And the results: