Testing PNG images

Post by **Sophia** » Tue Mar 07, 2006 8:42 pm

Gambit37 wrote:I was privileged to have 7 beta versions of v0.35 .... but at no point did GG hint at PNG support or all those extra sound formats!

I guess I didn't see the point of keeping even the beta testers in the dark about the new features-- they can't test what they never see, and the amount of bugs in the new features suggests that a bit more testing would've been nice.

Post by **Gambit37** » Tue Mar 07, 2006 10:01 pm

I understand where you're coming from, but at the same time, I can understand the 'wow' factor about including something that we've been asking for and more or less given up on. It was a great surprise!

Post by **Sophia** » Tue Mar 07, 2006 10:21 pm

Hehe, yeah..

"Wow! This is so cool!"

5 minutes later...

"Wow! It doesn't work!"

Post by **Gambit37** » Tue Mar 07, 2006 10:28 pm

I've tried a few things with PNG already and they worked for me. Don't be so harsh about one image that crashed your dungeon. Maybe it's a weird flavour of PNG? How are you saving it?

Post by **Sophia** » Tue Mar 07, 2006 10:48 pm

I think it has to do with trying to replace blue haze and fluxcages with a PNG with an alpha channel, and not anything to do with the PNG itself... I tried a few images and they all crashed when used like this. Of course, they were all generated by the same program (Paint Shop Pro) so if the program itself does something weird when saving, who knows!

The PNGs themselves are noninterlaced, truecolor with an alpha channel obviously... beyond that, I don't really know enough about the format to say anything useful about it.

For the record, it wasn't my intention to be 'harsh,' merely point out that the surprise was two-fold.

Post by **Gambit37** » Tue Mar 07, 2006 10:56 pm

I'll try with one from PhotoShop and I'll clean it up using the various PNG utils I've got and see if anything has the same effect.

George Gilbert · Post by **George Gilbert** » Tue Mar 07, 2006 11:18 pm

I've now reproduced the problem - it's nothing to do with PNG at all.

You can get it to crash by using an ordinary bitmap for the blue haze, but with setting the transparent flag to TRUE. So I'd say, you didn't test the code you were given in the first place well enough

Post by **Sophia** » Tue Mar 07, 2006 11:34 pm

Oh! Can't trust those beta testers to do anything right, can you?

Will a PNG still be transparent even if you don't set the transparent flag?

George Gilbert · Post by **George Gilbert** » Wed Mar 08, 2006 12:02 am

The transparent flag gives every pixel in the bitmap an alpha value of 0.5 (128). If the image already had an alpha channel, then it halves the value of each existing alpha value.

So, to answer your question - yes. In fact, for PNG images, you'd probably never want to set the transparent flag to TRUE (because even if you wanted it to be 50% transparent, you might as well do it explicitly in the alpha channel).