Crop/Scale Canvas Maniplators: fixed off-by-1 errors

[dsizzle]

New fix for #552 - now you can crop to 1x1 and it's actually 1x1, and I believe other crops are accurate too.

Also fixed Canvas->Resize since it's kind of the same thing (and had the same problem).

I didn't mess with Edit->Scale; I think it's also off by 1 but it's a lot hairier in general.

[humdingerb]

Crash when invoking Canvas|Resize... twice without changing anything but confirming both times with "OK" button:
ArtPaint-11210-debug-05-10-2023-14-30-15.report.txt

No crash when cropping twice.

Otherwise it does indeed seem to fix the cropping one-off.
There's still something off with resizing. I don't have the time to test thorougly ATM, but here's one thing:

• Canvas | Resize...
• Uncheck "Lock"
• Increase width by 1

And the result is 3 pixels wider.

[dsizzle]

I fixed the weird shearing - and it seems to correctly only expand by 1 pixel in width.

Still looking into the crash. Seems like it's related to trying to change the size when clicking Ok instead of not doing anything.

[dsizzle]

I think I fixed the crash as well - but I will try to test more.

[humdingerb]

Looks good!

Can you remind me why there's a "Left" and "Top" in the Resize panel? For cropping, it works - it de/increases the canvas size. For resizing it does nothing.
It could have a use, if entering e.g. 100 in "Top" decreased the "Height" by 100 (respecting the "Lock" checkbox to decrease the width accordingly).

[dsizzle]

Honestly I don’t recall. I think it was just for consistency. But yeah, I guess it is kinda pointless. Even if it worked as you suggested, it’s no different from decreasing the width or height.

[humdingerb]

True. At max. it saves you from mental arithmatic when having to subtract, say 283 from 1292 for the new width.

[dsizzle]

Ok, after sleeping on it, I think I remember why we have the Left/Top - it's simply because of the resize box. So when you move the upper left handle, it does behave as you describe.

Anyway, since this seems to have fixed the original issue, I'll go ahead and merge it later.

[humdingerb]

👍

[dsizzle]

merged!