Inform 7 IDE allows Figures to be png,jpg,gif no release gif

Authoring Inform 7
1

I did a quick scan of the Inform 7 issues for ‘gif’ but didn’t find anything.

It is an official thing to not allow ‘gif’ images as part of Glulx VM standard? They seem to work fine in the IDE when running the code… but when you go to do a Release Inform 7 complains Error: image file has unknown file extension (expected e.g. ‘.png’ for PNG, ‘.jpeg’ for JPEG). I know it wasn’t “until 2004 all the relevant patents had expired” and it may have been avoided in the past due to that issue? But a lot of free images off Wikimedia are image/gif, etc.

2

This isn’t a limitation of Glulx per se; Glulx just passes images through to Glk, and Glk doesn’t specify particular image formats.

However, the Blorb package format specifies only PNG or JPEG. The error arises when Inform tries to insert the GIF image into the Blorb.

From the spec: “GIF is a popular format, but was previously owned by twits who restricted its use. (Life has improved, but we have PNG now and we will stick with it.) […] Blorb is likely to stay with PNG and JPEG for the foreseeable future […] GIF and MP3 are not going to become standard Blorb format types.”

3

Converting gif to png is always possible. (Unless you want animation, but the spec has never supported animated images.)

4

Well, most graphic rendering libraries don’t go by filename and actually look at the binary header of the file. So I renamed it to a .jpg (despite being a gif) and it works fine this way in the Inform 7 internal VM… not an ideal solution, but it works within the IDE and Quixe :wink: Well, I guess it causes Gargoyle to immediately crash (exit), as it detects the issue (“Not a JPEG file: starts with 0x47 0x49”) haha.

I was surprised that Chrome doesn’t run animated png. Because of this, a lot of people use gif. phoronix.com/scan.php?page= … mated-APNG

5

It would be better if Inform did this, yes. But as you see, trying to fool the system in this way is a bad idea all around.