Smudge tool leaves a white trail instead of a transparent one

[lucaspontoexe]

Issue Summary

Smudge tool leaves a white trail instead of a transparent one. That can lead to problems if someone uses other background color than white.

Image Reference

https://puu.sh/wZhYJ/bd24d1e241.png

Steps to reproduce

1. Change the background to checkerboard on Preferences
2. Draw something on a bitmap layer
3. Drag using smudge tool
4. and there's it

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[lucaspontoexe]

such an abstract modern art tho :P

[Jose-Moreno]

@lucaspontoexe Can you test the latest development version to see if this continues to happen for you? I've seen the smudge tool works better now, however the blur tool has this same problem still (Smudge: ALT+LMB), however if the smudge has been fixed for you then please close this and open a new issue for the blur tool if you want. Thanks :slightly_smiling_face:

[lucaspontoexe]

I did some tests with the latest nightly build and the result is still the same. This time, I created a layer behind the main one

[data from "about" dialog] Versão: 0.6.1.1 commit: 52db352d2bc25e650448f5b0e9c92aba14e11a64 date: 2018-06-16_11:45:26 Development build Operating System: Windows 10 (10.0) CPU Architecture: x86_64

[Jose-Moreno]

@lucaspontoexe Thanks a lot. Then we'll leave this issue open until devs can visit it again and fix it. :smile:

[davidlamhauge]

I have spent some time looking into this problem, and it puzzles me that it ever worked, so my first question is: can anyone confirm if smudge ever worked? and when?

[Jose-Moreno]

@davidlamhauge It worked quite better in 0.5.4 dev (you know it is that version because it had an additional debug window that was removed) but it still was more akin to Photoshop's "finger painting" where you smudge and apply color (white in this case), but it was still a bit of a WIP, however, somehow, on later versions the behavior worsened and even crashed the software plenty when using it.

[davidlamhauge]

@Jose-Moreno Yeah, but it still smudges with white paint as I see it, and that can't be the wanted behaviour? Is that from the time when it worked? It should smudge the line in a fashion that blurs it with transparency, imo.

[Jose-Moreno]

Yeah the white paint is unwanted.

[lucaspontoexe]

I'm not experienced with Qt, but I think the white trail might be related to the source mode that is being used.

I'm pasting a link of all modes, just for convenience https://doc.qt.io/qt-5/qpainter.html#composition-modes

[MrStevns]

Fixed in 79ede5042ddf29af993768725b614eb6a0495276 Will be available in next nightly build.

[Jose-Moreno]

@CandyFace @scribblemaniac I'm reopening this. I've tested the following build

Development Build Jul 30 2020 commit: b2d8535ea71c9140d78ad6329df64d823e74220e date: 2020-07-30_12:19:20

Operating System: Windows 10 (10.0) CPU Architecture: x86_64 Qt Version: 5.12.9

And I get the same result as Lucas as seen here:

[Kaikogf]

[REVIEW Jan2021]

I tested with the last build [04Jan2021], and I must say it its a LOT better.

After playing around this issue I came to a conclusion.

The mixing feature provided by the Smudge tool is a lot better. In order to avoid the white artefacts while using this tool, we should take into account to have a maximum range value of 45 approximately between the feather and the width tool for the Smudge tool to work properly without showing the white artefacts. Meaning that if the feather tool displays a value of 99 so the width tool should displays a value higher than 50.