Color Picker Blending Feature: Advice Needed!

[David Revoy]

Hi Emmet, 
Interesting and as you already mentioned ; even more interesting if the tool-options of the dedicated color-picker tool could affect the one used while painting with the brush tool ( or with the fill tool, or other drawing tools) using the <ctrl> key shortcut. 
-David​​

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On April 1, 2018 1:18 PM, Boudewijn Rempt <boud at valdyas.org> wrote:

> ​​
> 
> 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