Re:

[Eli Zaretskii <eliz@gnu.org>]

[Please keep the list address on the CC.]

> From: Davin Pearson <davin.pearson@gmail.com>
> Date: Tue, 28 Dec 2021 16:58:50 +1300
> 
> In your email to me you said that one of the foreground colours
> will "win" and the other will be ignored.  What I want is the
> same thing for the background colour.  As far as I understand the
> winning foreground colour will be the one that is added last in
> the fontification spec, and with the symbol 'end added to
> font-lock-add-keywords.
> 
> Here is my font-lock-string-face
> 
> "assdsdasd"
> 
> Here is the text dmp-asdssd coloured in my choice of colours: red
> and green:
> 
> "dmp-asdssd" (*)
> 
> Here is the code that fontifies the above code.
> 
> (make-face 'dmp-face--line0--col1-red)
> (set-face-foreground 'dmp-face--line0--col1-red "#ff0000")
> (set-face-background 'dmp-face--line0--col1-red nil)
> (make-face-bold 'dmp-face--line0--col1-red)
> 
> (make-face 'dmp-face--line0--col2-green)
> (set-face-foreground 'dmp-face--line0--col2-green "#00ff00")
> (set-face-background 'dmp-face--line0--col2-green nil)
> (make-face-bold 'dmp-face--line0--col2-green)
> 
> (make-face 'dmp-face--line0--col3-blue)
> (set-face-foreground 'dmp-face--line0--col3-blue "#0000ff")
> (set-face-background 'dmp-face--line0--col3-blue nil)
> (make-face-bold 'dmp-face--line0--col3-blue)
> 
> Here are some useful constant strings:
> 
> (defvar dmp-defun-inner-regexp-less-dash+star "a-zA-Z0-9_.!@$%^&=<>/|+:;?~")
> (defvar dmp-defun-inner-regexp-less-dash      (concat ""  dmp-defun-inner-regexp-less-dash+star))
> (defvar dmp-defun-inner-regexp-less-star      (concat "-"  dmp-defun-inner-regexp-less-dash+star))
> (defvar dmp-defun-inner-regexp                (concat "-," dmp-defun-inner-regexp-less-dash+star))
> (defvar dmp-defun-outer-regexp                (concat "["  dmp-defun-inner-regexp            "]+"))
> (defvar dmp-bra                               "\\(^\\|[][ \t\r\n()'\",.:=]\\)")
> (defvar dmp-ket                               "\\($\\|[][ \t\r\n()\",.:=]\\)")
> 
> Here is the actual font lock code:
> 
> (defun dmp-getting--syntax-highlighting--online ()
>   (font-lock-add-keywords
>    'emacs-lisp-mode
>    '(
>      (, (format "\\(dmp[0-9]\\)\\(\\(-[%s]+\\)+\\)%s"
>                 dmp-defun-inner-regexp-less-dash
>                 dmp-ket)
>         (1 'dmp-face--line0--col1-red t)
>         (2 'dmp-face--line0--col2-green t)
>         )
>      (, (format "\\(dmp[0-9]\\(-[%s]+\\)\\)\\(\\([-_][-_]\\|:\\)[%s]+\\)%s"
>                 dmp-defun-inner-regexp-less-dash
>                 dmp-defun-inner-regexp
>                 dmp-ket)
>         (1 'dmp-face--line0--col1-red t)
>         (3 'dmp-face--line0--col2-green t))
>      (, (format "\\(dmp[0-9]*\\(-[%s]+\\)*\\)\\([_-][_-][%s]+\\)\\([_-][_-][%s]+\\)%s"
>                 *dmp-defun-inner-regexp-less-dash*
>                 *dmp-defun-inner-regexp*
>                 *dmp-defun-inner-regexp*
>                 *dmp-ket*)
>         (1 'dmp-face--line0--col1-red t)
>         (3 'dmp-face--line0--col2-green t)
>         (4 'dmp-face--line0--col3-blue t))
>      )
>    'end)
>   )
> (add-hook 'font-lock-mode-hook 'dmp-getting--syntax-highlighting--online 'APPEND)
> 
> Notice that in the text marked with a (*) the background colour
> of the above text is the same as the background colour of the
> screen.
> 
> When dmp-face--line0--col1-red, dmp-face--line0--col2-green and
> dmp-face--line0--col3-blue 's set-face-foreground set to nil, as it
> is above, I want the for the string face's background colour to
> show through as light blue in the fontification of dmp-asdssd.

I think this is something that your code does.  If I just merge two
faces, one with a background color, the other with a foreground color,
the result of the merge has the background of the first faces and the
foreground of the second.

So I conclude that something goes wrong in your
dmp-getting--syntax-highlighting--on-line function, or in how it
interacts with font-lock.