Customize face foreground color value using the color of another face

Question

I am making some small customizations to my org-agenda view.

For the face called "Org Agenda Done", I am adding a strikethrough and changing the color.

The color I want to use is already defined as the foreground color for "Org Agenda Dimmed Todo Face".

Is there a way to define the color of "Org Agenda Done" using the value of "Org Agenda Dimmed Todo Face"?

Right now, I only see the option to define the color of the face with a hex value.

Answer 1

You can get and set face attributes using the functions described in the Face Attributes Functions section of the Emacs Lisp Reference manual.

E.g.:

(set-face-foreground 'org-agenda-done
                     (face-foreground 'org-agenda-dimmed-todo-face))

You can put this in your init file but you have to make sure that the faces are already defined. They are defined in the file org-faces.el[c], so you have to make sure that that file is loaded:

(require 'org-faces)
(set-face-foreground ...)

Answer 2

When defining your face, you can inherit from another face (or even faces). Note that if the original face should change after you have defined your face, your face will also change accordingly.

For example:

(defface my-extra-warning-face
  '((t :inherit font-lock-warning-face :background "green"))
  "My extra warning face.")

Answer 3

The customize interface accepts both color names and hex values. You can also press the button for choosing a color, the interface will show you a list of color names with their hex values. You can just search for the color name (C-s) of the Org Agenda Dimmed Todo Face face foreground color and select it.