how to attach properties to a piece of text?

how to attach properties to a piece of text?

[Xah Lee]

how to write a function that colors particular words matching regex
inside a region?

I was thinking using font-lock-add-keywords, but that does to the
whole buffer.

i haven't studied emacs's face, display property etc systems. But
could anyone give me a rough guide on what function i should use or
lookup?

Here's a bit detail on what i need to do. I'm writing a mode for
Linden scripting language (LSL). Colors are specified using lsl's
vector type, like this:

vector red = <1,0,0>;
vector green = <0,1,0>;
vector blue = <0,0,1>;
vector black = <0,0,0>;
vector white = <1,1,1>;
vector pink = <1,0.07843,0.5765>;
vector orange = <1,0.6471,0>;
vector brown = <0.5451,0.1373,0.1373>;
vector purple = <0.3333,0.102,0.5451>;
vector gold = <1,0.8431,0>;

I want to be able write a function, something named color-vectors-
region, so that any <r,g,b>'s background is colored using the rgb
value. (each is a float from 0 to 1.) The part i don't know how, is
how to attach a text color property to a piece of text.

Thanks.

  Xah
∑ http://xahlee.org/

☄

Re: how to attach properties to a piece of text?

[Miles Bader]

Xah Lee <xahlee@gmail.com> writes:
> i haven't studied emacs's face, display property etc systems. But
> could anyone give me a rough guide on what function i should use or
> lookup?

`put-text-property'

In particular, you may want the :foreground attribute of the `face'
property.

E.g. try evaluating the following:

   (put-text-property (point) (mark) 'face '(:foreground "green"))

However, note that if the buffer's mode uses font-lock, font-lock will
_override_ any `face' property you set (to be its own); in a font-lock'd
buffer, you can use the `font-lock-face' property instead:

   (put-text-property (point) (mark) 'font-lock-face '(:foreground "green"))


-Miles

-- 
Cynic, n. A blackguard whose faulty vision sees things as they are, not as
they ought to be. Hence the custom among the Scythians of plucking out a
cynic's eyes to improve his vision.

Re: how to attach properties to a piece of text?

[Xah Lee]

On Mar 18, 5:54 pm, Miles Bader <mi...@gnu.org> wrote:
> Xah Lee <xah...@gmail.com> writes:
> > i haven't studied emacs's face, display property etc systems. But
> > could anyone give me a rough guide on what function i should use or
> > lookup?
>
> `put-text-property'
>
> In particular, you may want the :foreground attribute of the `face'
> property.
>
> E.g. try evaluating the following:
>
>    (put-text-property (point) (mark) 'face '(:foreground "green"))
>
> However, note that if the buffer's mode uses font-lock, font-lock will
> _override_ any `face' property you set (to be its own); in a font-lock'd
> buffer, you can use the `font-lock-face' property instead:
>
>    (put-text-property (point) (mark) 'font-lock-face '(:foreground "green"))

Thanks Miles.

Here's the code i did.

(defun convert-rgb-vector-to-hex (rgb)
  "Convert color RGB from “[r g b]” notation to “\"rrggbb\"” notation.
Example:
 (convert-rgb-vector-to-hex [0 1 0.5])
returns
\"00ff80\"
"
  (mapconcat
   (lambda (x)
     (format "%02x" (round (* x 255.0)) ))
   rgb ""))

(defun syntax-color-vector (start end)
  "Make vectors <r,g,b> syntax colored "
  (interactive "r")
  (save-restriction
    (narrow-to-region start end)
    (goto-char (point-min))
    (while (search-forward-regexp
            "< *\\([0-9.]+\\) *, *\\([0-9.]+\\) *, *\\([0-9.]+\\) *>"
nil t)
      (put-text-property (match-beginning 0)
                         (match-end 0) 'face (list :background

(concat "#" (convert-rgb-vector-to-hex
             (vector
              (string-to-number (match-string 1))
              (string-to-number (match-string 2))
              (string-to-number (match-string 3))
              )))
)))))

spent some 4 hours on this. Some 80% time is spend on the hex/decimal
conversion, digging into some details of emacs float, string, hex,
round, etc issues. (^_^)

  Xah
∑ http://xahlee.org/

☄

RE: how to attach properties to a piece of text?

[Drew Adams]

> (defun convert-rgb-vector-to-hex (rgb)
>   "Convert color RGB from "[r g b]" notation to "\"rrggbb\"" notation.
> Example: (convert-rgb-vector-to-hex [0 1 0.5]) returns \"00ff80\""
>   (mapconcat (lambda (x) (format "%02x" (round (* x 255.0)) )) rgb ""))
> 
> (defun syntax-color-vector (start end)
>   "Make vectors <r,g,b> syntax colored "
>   (interactive "r")
>   (save-restriction
>     (narrow-to-region start end)
>     (goto-char (point-min))
>     (while (search-forward-regexp
>             "< *\\([0-9.]+\\) *, *\\([0-9.]+\\) *, *\\([0-9.]+\\) *>"
>             nil t)
>       (put-text-property (match-beginning 0)
>                          (match-end 0) 'face (list :background
> (concat "#" (convert-rgb-vector-to-hex
>              (vector (string-to-number (match-string 1))
>                      (string-to-number (match-string 2))
>                      (string-to-number (match-string 3))))))))))
> 
> spent some 4 hours on this. Some 80% time is spend on the hex/decimal
> conversion, digging into some details of emacs float, string, hex,
> round, etc issues. (^_^)


http://www.emacswiki.org/emacs/hexrgb.el (e.g. `hexrgb-rgb-to-hex')

But it's always rewarding to code something oneself - never a waste of time.

Re: how to attach properties to a piece of text?

[Xah Lee]

On Mar 18, 5:54 pm, Miles Bader <mi...@gnu.org> wrote:

> However, note that if the buffer's mode uses font-lock, font-lock will
> _override_ any `face' property you set (to be its own); in a font-lock'd
> buffer, you can use the `font-lock-face' property instead:
>
>    (put-text-property (point) (mark) 'font-lock-face '(:foreground "green"))

Great advice. That just happened to me after i put the function into
the package and tried to test it. Thanks.

  Xah
∑ http://xahlee.org/

☄