Thursday, 1 September 2016


Google Summer of Code

The Google Summer of Code for Krita is officially over.  I started a bit later due to my graduation, so therefore I will continue for two more weeks. Anyways, here is a little recap of what we achieved so far.

In Krita 3.0 we introduced some mechanisms that required the use of modern OpenGL functions. Using these modern OpenGL functions didn't turn out to be a problem on Windows and Linux. However, on Mac OS it forced us to switch to an OpenGL 3+ Core Profile in order to have access to these functions. This Core Profile also meant that all legacy functions would be illegal to use.

Krita is built on top of the Qt GUI framework, which we use for our whole user interface. Additionally, we use its QPainter class for drawing simple shapes, curves and lines. This class is very useful for rendering our painting assistants e.g. the perspective grid, vanishing point, ruler. Unfortunately, it uses these illegal legacy functions.

Over my Google Summer of Code period I have gone into the depths of Qt and upgraded their legacy OpenGL code to a modern variety. This allows people who explicitly request a modern OpenGL context to still use this useful QPainter class.

The result of this is that we can now fully support Krita's functionality on Mac OS. Whereas previously we had to disable Instant Preview to allow the user to still see canvas decorations and painting assistants, we can now offer both again.

It might take a while for Qt to release my patch in any of their official releases, so therefore we have decided to apply the patch manually to a custom version of Qt we already ship with Krita. This version should be available to you on the Krita 3.1 release.

The State of Mac OS

Over the past weekend many people from all over the world came together at the Krita Institute to discuss all sorts of matters. Several of these matters were about Krita bugs on Mac.

Some of you Mac + Krita users may be familiar with a bug that causes a lot of patches to appear on your screen. You might see interruptions in your paint strokes, parts that are partially transparent or full blown missing rectangles.
Together with Dmitry, Boud and Beelzy we looked at what might be causing these issues.

We have some idea of what is causing the problem, but it is a difficult bug to completely cure. As a temporary solution we have implemented a hot-fix that solves the problem. We are looking forward to feedback on whether this fix is appropriate.

In addition, Beelzy fixed a bug that caused blobs to appear at the beginning of tablet strokes.

Overall the state of Krita on Macs should be improved after the 3.1.0 release, but we will closely monitor any new problems.

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