Bug 367943

Summary: In wrap-around mode, dragging a brush with sharpness above or left of canvas is offset by half a pixel.
Product: [Applications] krita Reporter: Patrick McCarthy <mauve>
Component: Brush enginesAssignee: Krita Bugs <krita-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: freebox64
Priority: NOR    
Version: 3.0.1 Beta   
Target Milestone: ---   
Platform: Appimage   
OS: Linux   
Latest Commit: https://commits.kde.org/krita/b2c4e87d35ab1d04e9cbdc4889b0e93537b638a1 Version Fixed In:
Attachments: (Video example)

Description Patrick McCarthy 2016-08-29 03:49:21 UTC 
When in wrap-around mode, and using a Pixel-type brush that has Sharpness enabled, if you click-drag a brush at a negative coordinate (eg, left or above the main canvas), it will draw at a half pixel offset from that location. This is very, very noticeable with deevad's 5b pixel brush from his recent v8 brush set, and easily tested with it.

If you just do a single click and release, it draws at the correct position.


Reproducible: Always

Steps to Reproduce:
1. Turn on wrap-around mode.
2. Zoom in to something ridiculous like 1600%, to make the bug more apparent.
3. Use a brush with Sharpness enabled. Any strength is okay. deevad's 5b pixel brush works for this.
4. Click-drag on a pixel in negative coordinate space, either above or left of the main canvas. It will be offset.
Comment 1 mvowada 2016-08-31 06:51:30 UTC 
Created attachment 100855 [details]
(Video example)

I think I can confirm this behaviour ("Krita 3.0.1 beta" and "Krita 2.9.6" on Ubuntu 14.04 Unity). It happens to me with:

    - grid brushes, 
    - when in wrap around mode,
    - at the far left / top / right sides of the canvas.

Apparently no issues at the far right-bottom side of the canvas. No problems with pixel engine brushes on all sides.
Comment 2 Alvin Wong 2017-11-30 16:51:36 UTC 
Git commit b2c4e87d35ab1d04e9cbdc4889b0e93537b638a1 by Alvin Wong.
Committed on 30/11/2017 at 16:46.
Pushed by alvinwong into branch 'master'.

Fix rounding in wrap around mode for KisPainter

This fixes some of the rounding errors with negative coordinates when
painting, for example the pixel brush.
Differential Revision: https://phabricator.kde.org/D8898

M  +79   -86   libs/image/kis_painter.cc

https://commits.kde.org/krita/b2c4e87d35ab1d04e9cbdc4889b0e93537b638a1