Hi,
I sent this message two days ago but I still haven't gotten any answers.
Basically I want to understand how should I use getImageSize() and doTransform() on a
subclass of ImageHandler in a way to defer calculation of the image size only after the
transformation is done.
On my specific case, I want to use "dia" to convert .dia files to .png, and then
use PHP's getimagesize() to get the dimensions of the resulting .png file. The problem
is that, from what I saw, doTransform() is called after getImageSize(). Yes, I'm aware
of the "Dia" extension, but I found out that it does not handle the image size
correctly.
On the code of ImageHandler, there is a comment that suggests that I could return
"false" on getImageSize() if I still don't know the size of the image, but I
did not understand how to do that and set the appropriate size later.
If any of you could help me with this or point me to the appropriate resources or point me
to another mailing list where this subject could be handled I would really appreciate it.
Thanks!
Filipe
-----Original Message-----
From: "Filipe Brandenburger" <lists.filbranden(a)idilia.com>
Sent: Tuesday, September 2, 2008 11:22am
To: "Wikimedia developers" <wikitech-l(a)lists.wikimedia.org>
Subject: [Wikitech-l] Extension to render Dia as a PNG
Hello,
I need an extension to render Dia files as PNGs. I was using this one:
http://www.mediawiki.org/wiki/Extension:Dia
However I saw many problems with it, one of them being the wrong way to
calculate the size of the image.
I tried to fix it, but I did not find a good way to do it.
The extension creates a new class that extends ImageHandler. In
"doTransform" it calls the "dia" binary with special arguments to
convert a .dia file to a .png file. Nothing wrong there.
The problem is that it implements a "getImageSize" method where it
implements a method that reads the XML file to try to "guess" the size
of the image that "dia" will produce in "doTransform", and the
problem
is that it guesses wrong.
I think that the best way to do it would be actually to first generate
the PNG image by calling "dia", and then later returning the dimensions
of this PNG by using "getimagesize". The problem is that, as far as I
understood the source code, getImageSize will always be called before
doTransform. In fact, it seems to me that the name of the PNG image that
doTransform receives will start with the width of the image returned by
getImageSize itself.
I implemented a workaround^W^W a dirty hack to fix this issue. In
getImageSize, I am calling "dia" (without the size argument) saving it
to a tmpfile, then using "getimagesize" to get the dimensions of the PNG
in the tmpfile, and then deleting the tmpfile. Then doTransform is
called and it will basically do the same again, call "dia" to create the
image that will be displayed. It works, but it calls "dia" twice, thus
it is twice as slow as it should be.
Is there a way around this? To actually generate the PNG image just once
and calculate its size only once it is generated?
Thanks!
Filipe