Bug 503591

Summary:	"Save New Brush Preset..." dialog's brush thumbnail resolution seems dependent on Canvas Zoom factor
Product:	[Applications] krita	Reporter:	bgembara13+kdebugs
Component:	* Unknown	Assignee:	Krita Bugs <krita-bugs-null>
Status:	CONFIRMED ---
Severity:	minor	CC:	bgembara13+kdebugs, info, rand
Priority:	NOR
Version First Reported In:	5.2.9
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description bgembara13+kdebugs 2025-04-30 20:24:01 UTC

SUMMARY
The editable/drawable brush thumbnail presented on the "Save New Brush Preset..." dialog appears to be scaled (nearest neighbor) according to the canvas zoom factor at the time of entering the dialog. This affects the user's ability to create a thumbnail for new brushes.

STEPS TO REPRODUCE
1. Create a new 1024x1024 100.00 px/in canvas.
2. Zoom the canvas to 400%.
3. Enter the "Edit Brush Settings" menu from the toolbar.
4. Select "b) Basic-1" from the "Presets" pane.
5. Click "Save New Brush Preset..." in the top right of the brush settings pop-out.
6. Observe that the image displayed under "Paint in this area" appears pixelated.
7. Cancel out of that dialog.
8. Reset canvas zoom to 100%.
9. Return to the "Save New Brush Preset..." dialog via steps 3 ~ 5.
10. Observe that the image displayed under "Paint in this area" no longer appears pixelated. It seems to be "full resolution" and unscaled.

OBSERVED RESULT
Step 6: Under a zoom factor of 400%, the editable thumbnail in the "Save New Brush Preset..." dialog appears pixelated.

EXPECTED RESULT
The editable thumbnail in the "Save New Brush Preset..." dialog should appear "full resolution," as in Step 10, regardless of canvas zoom factor.

SOFTWARE/OS VERSIONS
`kinfo` output follows.

```
Operating System: Arch Linux
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.9.0
Kernel Version: 6.14.4-zen1-2-zen (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 7950X3D 16-Core Processor
Memory: 62.4 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 3080 Ti
```

Comment 1 Wolfgang Baer 2025-05-18 12:35:22 UTC

I tried in 5.3 prealpha on Windows 11.

The "paint here" in brush editor show the same zoom than the canvas.
If canvas is 400% the brush editor is also 400%
So the "stroke preview" in the brush editor is similar to the canvas.

This looks like intended behaviour to me?

Comment 2 Wolfgang Baer 2025-06-24 11:25:59 UTC

Comment to my own previous comment.

The behaviour of the "Paint here" area seems to show the same zoom step than the canvas.
Which might be intended.
But, as the op wrote, when saving the brush preset, this leads to saving a brush preview icon that looks wrong (e.g. blurry because of some kind of automatic downscaling if the canvas / paint here area was zoomed in).

I confirmed this as a bug, because a casual non tech savy user might not understand what is going on.

Comment 3 Rand Scullard 2025-09-05 14:26:09 UTC

I’ve been customizing some brush presets today, and I noticed that every time I save a preset (using the Overwrite Brush Preset button in the Brush Editor), the thumbnail image becomes progressively blurrier (not more pixelated, just blurrier). After reading this bug report, it sounds like this may be the cause. I can't recall what my canvas zoom factor was at the time I was saving presets.

I just wanted to point out that I was simply tweaking a preset and saving it, tweaking it some more and saving it, and so on. I wasn't interested in changing the thumbnail at all, yet it was getting messed up just by this simple operation. I feel like the user should be able to confidently tweak their brush presets without worrying about changing the thumbnail - if the user hasn't touched the thumbnail, it should stay exactly the same. This is an aspect of this behavior that I think is important and should be considered.