Color Picker Blending Feature: Advice Needed!

[Boudewijn Rempt]

That does sound interesting :-). It would most convenient if you  could post 
the patch on phabricator.kde.org so everyone can take a look and play with it!

On zondag 1 april 2018 01:54:41 CEST Emmet O'Neill wrote:
> Hi there, Krita community! I'm Emmet and I've been working on a small Krita
> feature patch together with my brother Eoin (pronounced Owen).
> 
> Essentially, we've come up with (and mostly implemented) a new feature for
> Krita's color picker that allows for mixing the newly picked color with the
> current color of the user's bush.
> This is a relatively small and simple change that we think makes a massive
> difference when it comes to painting and color mixing workflow, as it
> significantly reduces the need for on-canvas color blending techniques that
> have been the standard for digital painters.
> A great analogy and part of the inspiration for this idea is traditional
> painting, especially water-based painting. In watercolor or gouache, for
> example, if you dip your brush into a red puddle and then a blue puddle,
> your brush stroke will be some shade of purple on the page - the colors mix
> in the brush. The same thing happens to some degree in most forms of
> painting, and controlling this is a powerful tool for the traditional
> painter. So, what we're working on is a feature that adds configurable
> "blending" to Krita's color picker: when "blending" is set to full the
> color picker works as it always has by replacing your previous brush color
> with the newly picked color. However, when blending is set to a lower value
> (~1-99%) your previous brush color is partially mixed with the newly picked
> color, with each separate click of the color picker mixing in a little bit
> more. Obviously I'm a bit biased, but I think mixing colors this way feels
> amazing and very intuitive, much like dipping a brush into paint!
> 
> As of right now, we have this feature working while using the dedicated
> color picker tool (kis_tool_colorpicker) and we've added a small slider to
> control the blending amount to the color picker gui (wdgcolorpicker.ui).
> But color picker blending currently isn't working when using the "global"
> color picker that pops up when you press 'ctrl' while another tool is
> selected. This is where we're hoping that somebody who is more familiar
> with the Krita codebase can provide some advice with how to proceed! I
> think we've tracked down the relevant code for the 'ctrl-picker' over in
> "kis_tool_utils" and "kis_color_picker_stroke_strategy", and while the code
> is pretty similar to the other dedicated color picker code, we've run into
> an issue: in "kis_tool_colorpicker.cc" we were able to easily get the
> previous brush color by calling
> "canvas()->resourceManager()->foregroundColor()" before mixing it with the
> picked color, but we're not sure how to access the foreground color from
> within "kis_color_picker_stroke_strategy.cc". Does anybody have any idea
> about the proper way of getting access to foregroundColor() from within the
> color picker stroke strategy code or alternatively passing it into that
> code at some other point?
> 
> It probably goes without saying that we're both new to the Krita codebase
> and contributing to open source projects in general! We'll gladly accept
> any guidance or suggestions, and if anybody wants to try out "color picker
> blending" for themselves I'd be happy to try to send a little patch over so
> you can see what we have so far.
> 
> Thanks, Emmet.


-- 
Boudewijn Rempt | https://www.valdyas.org | https://www.krita.org
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