php imagettftext letter spacing

function imagettftextSp($image, $size, $angle, $x, $y, $color, $font, $text, $spacing = 0)
{        
    if ($spacing == 0)
    {
        imagettftext($image, $size, $angle, $x, $y, $color, $font, $text);
    }
    else
    {
        $temp_x = $x;
        for ($i = 0; $i < strlen($text); $i++)
        {
            $bbox = imagettftext($image, $size, $angle, $temp_x, $y, $color, $font, $text[$i]);
            $temp_x += $spacing + ($bbox[2] - $bbox[0]);
        }
    }
}

and the call:

imagettftextSp($image, 30, 0, 30, 30, $black, 'arial.ttf', $text, 23);

Function parameters order meets standard imagettftext parameters order, and the last parameter is optional $spacing parameter. If not set or the passed value is 0, the kerning / letter spacing is not set.

I know this was answered a while back, but I needed a solution that had letter spacing and maintained the angular offsets.

I modified radzi's code to accomplish this:

function imagettftextSp($image, $size, $angle, $x, $y, $color, $font, $text, $spacing = 0)
{        
    if ($spacing == 0)
    {
        imagettftext($image, $size, $angle, $x, $y, $color, $font, $text);
    }
    else
    {
        $temp_x = $x;
        $temp_y = $y;
        for ($i = 0; $i < strlen($text); $i++)
        {
            imagettftext($image, $size, $angle, $temp_x, $temp_y, $color, $font, $text[$i]);
            $bbox = imagettfbbox($size, 0, $font, $text[$i]);
            $temp_x += cos(deg2rad($angle)) * ($spacing + ($bbox[2] - $bbox[0]));
            $temp_y -= sin(deg2rad($angle)) * ($spacing + ($bbox[2] - $bbox[0]));
        }
    }
}

Just to complete pidalia's answer (which is the best) to avoid some trouble with special char (like "é" or "à")

static function imagettftextSp($image, $size, $angle, $x, $y, $color, $font, $text, $spacing = 0) {
    if ($spacing == 0) {
        imagettftext($image, $size, $angle, $x, $y, $color, $font, $text);
    } else {
        $temp_x = $x;
        $temp_y = $y;
        //to avoid special char problems
        $char_array = preg_split('//u',$text, -1, PREG_SPLIT_NO_EMPTY);
        foreach($char_array as $char) {
            imagettftext($image, $size, $angle, $temp_x, $temp_y, $color, $font, $char);
            $bbox = imagettfbbox($size, 0, $font, $char);
            $temp_x += cos(deg2rad($angle)) * ($spacing + ($bbox[2] - $bbox[0]));
            $temp_y -= sin(deg2rad($angle)) * ($spacing + ($bbox[2] - $bbox[0]));
        }
    }
}