467,875 Members | 1,464 Online
Bytes | Developer Community
New Post

Home Posts Topics Members FAQ

Post your question to a community of 467,875 developers. It's quick & easy.

Why do imagettfbbox coordinates change when angle changes?

Hi,

I'm using php 4.4.4. Maybe I'm misreading the docs, but in the
imagettfbbox manual (http://us2.php.net/imagettfbbox), it says that
text coordinates are the same regardless of what the angle is. But I
am getting two distinct sets of coordinates if I change the angle from
zero to 270.

Here's the relevant code:

$text = "hello";
$s = getImageSize($img_file);
$imgWidth = $s[0];
$imgHeight = $s[1];
$source=ImageCreateFromJPEG($img_file);
$size=16;
$black=imagecolorallocate($source,0,0,0);
$font='/usr/share/fonts/msttcorefonts/times.ttf';
$bbox=imagettfbbox($size,$angle,$font,$text);
$textWidth=$bbox[2]-$bbox[0];
$textHeight=$bbox[5]-$bbox[3];
$x=($imgWidth/2)-($textWidth/2);
$y=($imgHeight/2)-($textHeight/2);
imagettftext($source,$size,$angle,$x,$y,$black,$fo nt,$text );
header("Content-type: image/jpeg");

When I print out the bbox with 0, I get

Array ( [0] =-3 [1] =-1 [2] =41 [3] =-1 [4] =41 [5] =-16
[6] =-3 [7] =-16 )

with 270, I get

Array ( [0] =-13 [1] =-1 [2] =-13 [3] =41 [4] =-1 [5] =41
[6] =-1 [7] =-1 )

I must be misinterpreting the docs. Why are the coordinates
different? - Dave
Mar 13 '08 #1
  • viewed: 2215
Share:
2 Replies
On Thu, 13 Mar 2008 18:18:13 +0100, la***********@zipmail.com
<la***********@zipmail.comwrote:
I'm using php 4.4.4. Maybe I'm misreading the docs, but in the
imagettfbbox manual (http://us2.php.net/imagettfbbox), it says that
text coordinates are the same regardless of what the angle is.
Nope
But I
am getting two distinct sets of coordinates if I change the angle from
zero to 270.

Here's the relevant code:

$text = "hello";
$s = getImageSize($img_file);
$imgWidth = $s[0];
$imgHeight = $s[1];
$source=ImageCreateFromJPEG($img_file);
$size=16;
$black=imagecolorallocate($source,0,0,0);
$font='/usr/share/fonts/msttcorefonts/times.ttf';
$bbox=imagettfbbox($size,$angle,$font,$text);
$textWidth=$bbox[2]-$bbox[0];
$textHeight=$bbox[5]-$bbox[3];
$x=($imgWidth/2)-($textWidth/2);
$y=($imgHeight/2)-($textHeight/2);
imagettftext($source,$size,$angle,$x,$y,$black,$fo nt,$text );
header("Content-type: image/jpeg");

When I print out the bbox with 0, I get

Array ( [0] =-3 [1] =-1 [2] =41 [3] =-1 [4] =41 [5] =-16
[6] =-3 [7] =-16 )

with 270, I get

Array ( [0] =-13 [1] =-1 [2] =-13 [3] =41 [4] =-1 [5] =41
[6] =-1 [7] =-1 )

I must be misinterpreting the docs. Why are the coordinates
different? - Dave
"The points are relative to the text regardless of the angle , so "upper
left" means in the top left-hand corner seeing the text horizontally."

Which means that with normal text without an angle, you have this box with
the array-indexes:
6,7---------4,5
| |
0,1---------2,3

However, if you have an angle of 180 (text upside down), you see this
picture:
2,3---------0,1
| |
4,5---------6,7

So, 0 & 1 hold the 'lower left corner IF you see the text horizontally' as
opposed to the 'lower left corner if you look at the picture'. The
coordinates WILL change if the angele changes (how could they not?), but
the different indexes will be for the same relative position from the text
if you were to look at the image the way the text appears horizontal
again. (Damned, this is far more easily explained face-to-face by just
rotating a piece of paper...).
--
Rik Wasmus
Mar 13 '08 #2
Greetings, Rik Wasmus.
In reply to Your message dated Thursday, March 13, 2008, 21:31:59,
(Damned, this is far more easily explained face-to-face by just
rotating a piece of paper...).
QFT :D

Thanks BTW, I was about to use this function myself and You just saved me time
to uncover this info by my own trials and errors.
--
Sincerely Yours, AnrDaemon <an*******@freemail.ru>

Apr 2 '08 #3

This discussion thread is closed

Replies have been disabled for this discussion.

Similar topics

5 posts views Thread by Gerrit Holl | last post: by
5 posts views Thread by Darren Grant | last post: by
1 post views Thread by Siegfried Heintze | last post: by
9 posts views Thread by pcnerd | last post: by
8 posts views Thread by giloosh | last post: by
3 posts views Thread by jackiepatti | last post: by
eragon
12 posts views Thread by eragon | last post: by
reply views Thread by mingke | last post: by
By using this site, you agree to our Privacy Policy and Terms of Use.