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$append_string:
Ein optionaler String welcher bei gekürzten Texten angehängt wird. Standardmässig "..."

Beispiel

Sie können die Methode nach folgendem Schema aufrufen:

echo trim_by_width('this is a long text',55,dirname(__FILE__) . '/verdana.ttf',8);

Das Script geht davon aus, dass sich die Datei verdana.ttf im gleichen Verzeichnis wie das PHP Script befindet. Anschliessend wird der Text nach 55 Pixel gekürzt und ausgegeben.

Fertig!

Measuring string width

PHP offers several methods to measure a string width. You can use the built in method ImageFontWidth to measure the width of a string using the built in PHP fonts. This is quite easy and works well if you want to create a captcha or something similar, using the PHP fonts.

But there's another method which you can easily use to get the complete bounding box of a true type font string. It's called imagettfbbox. The return value is an array which contains several values needed for a bounding box.

The trimming method

As you've probably seen on the picure at the beginning of the article, I needed a method that cuts off a string after a certain width and adds a string to indicate that the text isn't completely shown. Here's some code:

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function trim_by_width($text,$width,$font_file,$font_size=7,$append_string = '...')
{
	$append_string_box = imagettfbbox($font_size,0,$font_file,$append_string);
	$append_string_width = $append_string_box[2];
 
	$str_len = strlen($text);
	for ($i = 0; $i<=$str_len; $i++)
	{
		$trimmed_text = substr($text,0,$i);
		$bounding_box = imagettfbbox($font_size,0,$font_file,$trimmed_text);
		$trimmed_text_width = $bounding_box[2];
		if ($trimmed_text_width + $append_string_width > $width && $i > 0)
		{
			$str_to_return = substr($trimmed_text,0,strlen($trimmed_text)-1);
			if ($trimmed_text_width != $str_len)
			{
				$str_to_return .= $append_string;
			}
			return $str_to_return;
		}
	}
	return $text;
}

$trimmed_text = trim_by_width($text, $width, $font_file, $font_size, $append_string='...');

$text:
The first parameter is the string which you want to trim

$width:
This defines the maximum width of the text in pixels! Not in characters or anything else

$font_file:
Here you have to specify the location of your true type font file.

$font_size:
The font size you want to use. Please note that unit depends on the version of the GD library you're using. GD1 uses pixels, whereas GD2 uses points

$append_string:
An optional string to define the text appended at the end of a trimmed text. By default set to "..."

An example

You can call the method like this:

echo trim_by_width('this is a long text',55,dirname(__FILE__) . '/verdana.ttf',8);

It assumes that the file verdana.ttf is in the same directory as the php script. It will cut the text "this is a long text" after 55 pixels.

That's it!