Edit report at https://bugs.php.net/bug.php?id=53504&edit=1
ID: 53504
Comment by: mplomer at gmx dot de
Reported by: chris at nugc dot net
Summary: imagettfbbox gives incorrect values for bounding box
Status: Open
Type: Bug
Package: GD related
Operating System: Windows 7
PHP Version: 5.3.3
Block user comment: N
Private report: N
New Comment:
I had similar problems and created a pull-request which should fix several (hopefully all :-))
concurring bugs/problems in calculating the bounding box in imagettfbbox/imageftbbox. Also fixed
kerning for angle != 0.
It would be nice to have the fix in PHP 5.6 branch (and above of course):
https://github.com/php/php-src/pull/1845
Previous Comments:
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[2016-02-23 12:43:55] cmb@php.net
Related To: Bug #71602
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[2010-12-09 10:59:20] chris at nugc dot net
Description:
------------
imagettfbbox() function is unreliable. Tried at several different angles (including 0) with several
characters at the test script. The spacing around some letters is wrong, seemingly random parts of
letters are chopped off, some have too much space etc. I have tested this with 4 or 5 different TTF
fonts at different sizes, and the results are the same.
I am trying to use this to calculate spacing between letters, and can't, because of this
function's behaviour. I am having to write my own php function to accomplish the same thing,
and cache the results due to the poorer performance.
Script used in the example is 'Bauhaus 93', a font bundled with Windows, but the behaviour
is common to all fonts.
Test script:
---------------
<?php
$strText = "EXAMPLE";
$imgOutput = imagecreate(1640, 1640);
$colWhite = imagecolorallocate($imgOutput, 255, 255, 255);
$colBlack = imagecolorallocate($imgOutput, 0, 0, 0);
$colRed = imagecolorallocate($imgOutput, 255, 0, 0);
imagefilledrectangle($imgOutput, 0, 0, 1640, 1640, $colWhite);
for ($angle = 0; $angle < 360; $angle += 30)
for ($i = 0; $i < strlen($strText); $i++) {
$intX = 820 + (200 + ($i * 90)) * cos(deg2rad($angle));
$intY = 820 - (200 + ($i * 90)) * sin(deg2rad($angle));
imagettftext($imgOutput, 70, $angle, $intX, $intY, $colBlack, "./fonts/BAUHS93.TTF",
$strText{$i});
$arrBoundingBox = imagettfbbox(70, $angle, "./fonts/BAUHS93.TTF", $strText{$i});
imageline($imgOutput, $arrBoundingBox[0] + $intX, $arrBoundingBox[1] + $intY,
$arrBoundingBox[2] + $intX, $arrBoundingBox[3] + $intY, $colRed);
imageline($imgOutput, $arrBoundingBox[2] + $intX, $arrBoundingBox[3] + $intY,
$arrBoundingBox[4] + $intX, $arrBoundingBox[5] + $intY, $colRed);
imageline($imgOutput, $arrBoundingBox[4] + $intX, $arrBoundingBox[5] + $intY,
$arrBoundingBox[6] + $intX, $arrBoundingBox[7] + $intY, $colRed);
imageline($imgOutput, $arrBoundingBox[6] + $intX, $arrBoundingBox[7] + $intY,
$arrBoundingBox[0] + $intX, $arrBoundingBox[1] + $intY, $colRed);
}//for
header('Content-type: image/png');
imagepng($imgOutput);
Expected result:
----------------
An image with the word 'EXAMPLE' printed out in angles incrementing by 30 degrees, and
with a red box around each letter marking the bounding box of each character in turn.
Actual result:
--------------
The red boxes do not indicate the bounds of the character, but chop parts off and leave big spaces
in other places, seemingly unpredictably.
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Edit this bug report at https://bugs.php.net/bug.php?id=53504&edit=1