Comments on: libPNG Tutorial: Loading PNG files from streams

By: Michael

Michael — Sun, 27 Jun 2010 14:14:38 +0000

Thanks for this tutorial, it’s been of great value!

By: Ra

Ra — Fri, 02 Apr 2010 23:42:57 +0000

Thanks and congratulations for this great tutorial! Salud!

By: Wracky

Wracky — Wed, 17 Mar 2010 20:41:30 +0000

Thanks for noticing! You’re the first to notice it out of the 2.400+ people that have viewed the tutorial so far I’ve made a test case and it would indeed crash. I’ve updated the tutorial. Thanks again!!

By: Tom

Tom — Mon, 15 Mar 2010 22:34:03 +0000

I’m not sure, but you use all those filters to change bit depths and stuff, and you still use the old depths and everything for you arrays. Shouldn’t you update these values as well?

By: Wracky

Wracky — Thu, 11 Mar 2010 22:39:36 +0000

yeah you are right…I know its not the best option. I think i’ll spend some more time on this later and change the tutorial to use the callbacks for error handling. Thanks for the reply!

By: xlq

xlq — Thu, 11 Mar 2010 21:46:47 +0000

Watch out for setjmp/longjmp and C++. If you’re using function-scope non-pod objects and you’re not careful, libpng could longjmp over some destructor calls and leak memory/cause undefined behaviour. Also, if something throws an exception in there, such as new, you’ll leak all your buffers and PNG structures.

By: DPurple

DPurple — Sat, 20 Feb 2010 05:43:00 +0000

Great tutorial, helped me a lot!
thanks!

By: Wracky

Wracky — Tue, 02 Feb 2010 15:06:01 +0000

Changed it! Thanks for the comment

By: nevelis

nevelis — Mon, 01 Feb 2010 21:21:27 +0000

Shouldn’t:

for (size_t i = 0; i < bufferHeight; i++)

be:

for (size_t i = 0; i < imgHeight; i++)
?

Great tut

Cheers!

By: Guest

Guest — Tue, 19 Jan 2010 22:42:35 +0000

Thank you for this tutorial, very helpful.

>Funnily enough, this is also how a .BMP image is stored. (I don’t know why! if anyone knows, leave a comment! )

That’s because in 3D applications one of the axises (Y or Z) is usually directed straight up, not down. This would create additional inconsistency, if (U, V) image coordinates and (X, Y)/(X, Z) world coordinates will not be conformed.