[BUG] Selection mask always has padding applied even when padding is disabled

[Pauan]

1. Create this custom graph workflow:
   

2. Disable all padding related settings:
   

3. Create a selection and run the custom workflow. There is black padding around the selection, even though there shouldn't be:
   

[Acly]

Is your selection smaller than 256 pixels?

krita-ai-diffusion/ai_diffusion/model.py

Line 521 in 33993f9

mods = get_selection_modifiers(Arch.sdxl, InpaintMode.fill, self.strength)

This call has a default min_size=256, maybe set it to 0 will fix it.

[Pauan]

It happens on all selections, even very large selections. This is an 800x800 selection that still has the black padding:

I also confirmed that setting min_size=0 does not fix the bug.

[Acly]

Looks like it's

1. min_size=256 (if smaller than 256)
2. multiple=8 (if not multiple of 8)
3. sub-pixel size of the selection (when size is not exactly 800.0, but something like 800.2)

My take:

1. should be fixed.
2. should maybe be fixed? it means you can't use it as-is for diffusion or it will be auto-padded later by ComfyUI and you might get output size mismatch if you're not careful, so not sure if it's actually a good idea. but you could argue that mask bounds should really mean (exact) mask bounds.
3. not a bug, snap your Krita selection to full pixels if you want to avoid it

[Pauan]

but you could argue that mask bounds should really mean (exact) mask bounds.

But what if the user wants the mask bounds to be a multiple of 8? Now there's no longer any way to do that, since it's cropped too small, and there's no way to enlarge the crop.

But with the Krita Selection Bounds node the user can choose how to round it however they want.

[Acly]

Well the idea is:

• automatic: do sensible stuff according to user settings, including min size and multiple of 8 (now 16)
• mask bounds: use mask bounds exactly, 0 magic (+ fixed padding from workflow)
• entire image: full flexibility to do your own crops in the workflow

so that covers everything.

I did find some more places with padding after last release unfortunately, but I think with the latest commit it now gives mask bounds precisly.

[Pauan]

entire image: full flexibility to do your own crops in the workflow

That might be your intention, but it is not reality, because without the Krita Selection Bounds node there is no way to get the selection bounds in entire image mode.

Since you are so convinced that you are right, it should be easy for you to prove it by creating a workflow that:

• Uses entire image mode.
• Crops the canvas to the selection bounds, rounded up to the nearest multiple of 8.

This emulates the old behavior of mask bounds mode.

Note that using automatic mode is not acceptable for this, since it adds automatic padding, so it really must be in entire image mode.