image datablocks report 1 user if they've ever been opened in the image editor but have no actual users. #89644

New Issue

michael campbell · 2021-07-04T13:12:27+02:00

michael campbell commented

2021-07-04 13:12:27 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92

Blender Version
Broken: version: 2.93.2 Release Candidate, branch: master, commit date: 2021-06-23 12:44, hash: 03d5c8b4ed
Worked: (newest version of Blender that worked as expected)

Short description of error
image datablocks report 1 user if they've ever been opened in the image editor but have no actual users.

Exact steps for others to reproduce the error

open a Compositor editor
add an image node
load in an image
add an Image editor to the workspace
select the image you loaded to view in the image editor
now remove it from the image editor by pressing the x, (or just choose another image to view)
delete the node that uses the image
check in the blend data and you'll see it still has one user.

This is problematic, because it means you cant delete image datablocks via python if they have no users, because they always report as having one if they ever appeared in the image editor.

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.92 **Blender Version** Broken: version: 2.93.2 Release Candidate, branch: master, commit date: 2021-06-23 12:44, hash: `03d5c8b4ed` Worked: (newest version of Blender that worked as expected) **Short description of error** image datablocks report 1 user if they've ever been opened in the image editor but have no actual users. **Exact steps for others to reproduce the error** - open a Compositor editor - add an image node - load in an image - add an Image editor to the workspace - select the image you loaded to view in the image editor - now remove it from the image editor by pressing the x, (or just choose another image to view) - delete the node that uses the image check in the blend data and you'll see it still has one user. This is problematic, because it means you cant delete image datablocks via python if they have no users, because they always report as having one if they ever appeared in the image editor.

michael campbell commented

2021-07-04 13:12:27 +02:00

Added subscriber: @3di

Pratik Borhade commented

2021-07-05 05:41:30 +02:00

Added subscriber: @PratikPB2123

Germano Cavalcante commented

2021-07-07 15:26:46 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-07-07 15:26:46 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Germano Cavalcante commented

2021-07-07 15:26:46 +02:00

I'm not sure if the Compositor step is really needed to reproduce the described behavior.
If you load the image into the image editor and press the x, the users are not reset either.
This is the same behavior in older versions of Blender.
It's as if every added image already comes with 1 user by default.
You need to press Shift + X to make the amount of users 0.

Did I misunderstand the problem?

I'm not sure if the Compositor step is really needed to reproduce the described behavior. If you load the image into the image editor and press the x, the users are not reset either. This is the same behavior in older versions of Blender. It's as if every added image already comes with 1 user by default. You need to press Shift + X to make the amount of users 0. Did I misunderstand the problem?

michael campbell commented

2021-07-08 11:54:38 +02:00

Hi Germano, yes I think you may have misunderstood. You're only getting one user by default because you're creating the image from the image editor. If you create it elsewhere then the image editor won't count towards it's users (it'll still be one user (the actual user/node) until you open it in an image editor, then it'll be two users).

Basically I have some python code which needs to remove the image datablock if it's not in actual use by a part of blender which is using it for calculations. I don't think the UI should be classed as a user because there doesn't appear to be a way to differentiate between an actual user and a UI user, so you have to manually loop through and check everything in the blend file which could potentially be using that datablock, which isn't very performant.

Perhaps datablock.users could return a list of users rather than just an integer. Then the programmer could check they type of users and ignore those that are of type UI (if that is a type)

Hi Germano, yes I think you may have misunderstood. You're only getting one user by default because you're creating the image from the image editor. If you create it elsewhere then the image editor won't count towards it's users (it'll still be one user (the actual user/node) until you open it in an image editor, then it'll be two users). Basically I have some python code which needs to remove the image datablock if it's not in actual use by a part of blender which is using it for calculations. I don't think the UI should be classed as a user because there doesn't appear to be a way to differentiate between an actual user and a UI user, so you have to manually loop through and check everything in the blend file which could potentially be using that datablock, which isn't very performant. Perhaps datablock.users could return a list of users rather than just an integer. Then the programmer could check they type of users and ignore those that are of type UI (if that is a type)

Germano Cavalcante commented

2021-07-08 16:55:17 +02:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Germano Cavalcante commented

2021-07-08 16:55:17 +02:00

Maybe the fact of viewing the image in the image editor adds 1 user is intentional?
The operator in X might intentionally avoid making the user quantity 0.
I have to study the code to be sure, but I still don't think it's a bug.

Maybe the fact of viewing the image in the image editor adds `1` user is intentional? The operator in `X` might intentionally avoid making the user quantity `0`. I have to study the code to be sure, but I still don't think it's a bug.

Bastien Montagne commented

2021-07-09 10:18:33 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2021-07-09 10:18:33 +02:00

there is indeed no bug here, currently Blender relies on non-null user count to keep data-blocks around. 'shallow' users like image editors use a mechanism (check how LIB_TAG_EXTRAUSER/LIB_TAG_EXTRAUSER_SET are used in the code) that ensures that there is at least one user set when an image is assigned to an image editor e.g..

We have plans to change a bit how IDs are handled (and freed) by Blender in the future, see #61209 (Always write unused IDs on save). But currently this behavior is expected and definitely not a bug.

there is indeed no bug here, currently Blender relies on non-null user count to keep data-blocks around. 'shallow' users like image editors use a mechanism (check how `LIB_TAG_EXTRAUSER`/`LIB_TAG_EXTRAUSER_SET` are used in the code) that ensures that there is at least one user set when an image is assigned to an image editor e.g.. We have plans to change a bit how IDs are handled (and freed) by Blender in the future, see #61209 (Always write unused IDs on save). But currently this behavior is expected and definitely not a bug.

Bastien Montagne commented

2021-07-09 10:18:49 +02:00

Changed status from 'Needs Developer To Reproduce' to: 'Archived'

Bastien Montagne closed this issue

2021-07-09 10:18:49 +02:00

michael campbell commented

2021-07-09 12:45:06 +02:00

@mont29 should it not remove the user when pressing X in the image editor? And so that I can ignore the user if it's part of the UI, is there a way to differentiate in python between an actual user, and a UI user.....if not, is it possible to remove the user from the image editor and other UI elements via python? something like:

for img in bpy.data.images:

  if 'one of my images' in img:
      for ui in ui_users:
          if img.name in ui.images:
              ui.images.remove(img)

Cheers 👍

@mont29 should it not remove the user when pressing X in the image editor? And so that I can ignore the user if it's part of the UI, is there a way to differentiate in python between an actual user, and a UI user.....if not, is it possible to remove the user from the image editor and other UI elements via python? something like: for img in bpy.data.images: ``` if 'one of my images' in img: for ui in ui_users: if img.name in ui.images: ui.images.remove(img) ``` Cheers 👍

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image datablocks report 1 user if they've ever been opened in the image editor but have no actual users. #89644