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Editorial Team
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Asked: 2026-05-13T07:17:01+00:00

The PHP code below generates text as a dynamically created image, how would I

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The PHP code below generates text as a dynamically created image, how would I be able to get the image to only be as large as the text? Thanks.

<?php
    header('Content-Type: image/jpeg');

    $text='Test';

    $img = imageCreate(200,200);

    imagecolorallocate($img, 255, 255, 255);

    $textColor = imagecolorallocate($img, 0, 0, 0); 

    imagefttext($img, 15, 0, 0, 55, $textColor, 'bgtbt.ttf', $text);

    imagejpeg($img);

    imagedestroy($img);
?>

UPDATE 1: I found the answer here with the example of the original poster – Creating IMage from Text in PHP – how can I make multiline?

UPDATE 2: Martin Geisler’s version also works well

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1 Answer

  1. Editorial Team

    When using a TrueType font, you use the imageftbbox function to obtain the bounding box for a string typeset with your font. The bounding box gives the offsets from the base-point to the four corners in the rectangle occupied by the text. So if you store the bounding box in $bb and use imagefttext to put text at ($x, $y), then the corners will have these coordinates:

    ($x + $bb[6], $y + $bb[7])         ($x + $bb[4], $y + $bb[5])
                          +-------+
                          | Hello |
                          +-------+
($x + $bb[0], $y + $bb[1])         ($x + $bb[2], $y + $bb[3])

    That tells us that we want an image width of ($x + $bb[2]) - ($x + $bb[6]) = $bb[2] - $bb[6] and similarly an image height of $bb[3] - $bb[7]. The text should then be rendered at coordinates (-$bb[6], -$bb[7]) inside that picture since we want to have

    (0, 0) = ($x + $bb[6], $y + $bb[7]) ==> $x = -$bb[6]  and $y = -$bb[7]

    You can try it out with this code. Put it into a file called img.php and browse to img.php?q=Hello to test:

    <?php
header("Content-type: image/png");

$q     = $_REQUEST['q'];
$font  = "Impact.ttf";
$size  = 30;
$bbox   = imageftbbox($size, 0, $font, $q);

$width  = $bbox[2] - $bbox[6];
$height = $bbox[3] - $bbox[7];

$im    = imagecreatetruecolor($width, $height);
$green = imagecolorallocate($im, 60, 240, 60);

imagefttext($im, $size, 0, -$bbox[6], -$bbox[7], $green, $font, $q);
imagepng($im);
imagedestroy($im);
?>

    If you use the bitmap fonts instead, then look at the imagefontwidth and imagefontheight functions.

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