I fixed my build and it behaves correctly on macOS
now.

M-x emacs-version
GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G6032)) of 2020-12-18

To make sure I understand it, did we start outsourcing color some point after 27.1?


> On Dec 18, 2020, at 10:00 AM, Alan Third <alan@idiocy.org> wrote:
> 
> On Fri, Dec 18, 2020 at 12:49:23AM +0000, Qiantan Hong wrote:
>> Is there any update on this bug?
>> The current behavior is unacceptable when the SVG color
>> is supposed to be the same as some color in Emacs
>> (in my case, I’m using SVG to build some UI elements),
>> The following code
>> 
>> (require 'svg)
>> 
>> (defun make-image (color)
>>  (let ((svg (svg-create 100 100)))
>>    (svg-rectangle svg 0 0 100 100 :fill color)
>>    (svg-image svg)))
>> 
>> (set-frame-parameter (window-frame) 'background-color “#f00000")
>> 
>> (insert (propertize " " 'display (make-image "#f00000")))
>> 
>> produce very notable color difference.
> 
> I can no longer replicate this on the master branch on macOS. We've
> out-sourced colour handling fully to librsvg now, so that may make the
> difference?
> 
> Either that or macOS is doing something unusual with colours, which I
> wouldn't rule out.
> --
> Alan Third