Using Layer Masks in Python 3.0 plugins

stargazy · **Joined:** Jun 28, 2025 **Posts:** 6

Hi, I am writing a smart sharpener plugin using python 3.0. I use a layer mask to define edges in the image which will be sharpened. Problem is: I can create and attach the layer mask, but I cannot apply the mask to the layer using the Gimp python library (the attach plugin doesn't exist - though it did in Gimp 2.10!). Without it the sharpener ignores the mask (and likewise for any plugin that uses a layer mask). Can anybody suggest a fix? Thanks.

gasMask · **Posted:** Fri Aug 08, 2025 12:01 pm **(#2)**

Hi stargazy,

I sifted through LMDT code and found this where I successfully applied a mask to its layer:

Code: Select all

if layer.get_mask():
    layer.set_apply_mask(True)
    layer.remove_mask(Gimp.MaskApplyMode.APPLY)

stargazy · **Joined:** Jun 28, 2025 **Posts:** 6

Hi gasMask,

Many thanks for your response. I will give your suggestion a try and report back!

Stargazy

stargazy · **Joined:** Jun 28, 2025 **Posts:** 6

Hi gasMask!

I have tried your suggestion and can confirm that it works as expected. Many thanks for your help - I would never have got there without your input. I had tried the layer.set_mask but didn't realize the mask had to be removed afterwards. It wasn't that way with Gimp 2.10, but I guess that's a common complaint these days!

Stargazy

quietreader · **Joined:** Apr 11, 2024 **Posts:** 306

Sometimes you really have to be creative using this new API.
But we'll get used to that ....
BTW...
Just in case you have not found it yet, API References are here:
https://developer.gimp.org/resource/api/

(Difficult to find if you don't know where to click on GIMP's homepage.
Would be nice to have it in the top navigation )