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| author | Hugo Hörnquist <hugo@lysator.liu.se> | 2020-08-17 18:39:53 +0200 |
|---|---|---|
| committer | Hugo Hörnquist <hugo@lysator.liu.se> | 2020-08-17 18:40:00 +0200 |
| commit | f12fca91b185cbf83fbe173fadf6a46f6c3c0c65 (patch) | |
| tree | de863658e3494ca3927095a28e44d0e1f4ce5d6d /module/util/color.scm | |
| parent | move terminal output. (diff) | |
| download | calp-f12fca91b185cbf83fbe173fadf6a46f6c3c0c65.tar.gz calp-f12fca91b185cbf83fbe173fadf6a46f6c3c0c65.tar.xz | |
Fixes.
Diffstat (limited to 'module/util/color.scm')
| -rw-r--r-- | module/util/color.scm | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/module/util/color.scm b/module/util/color.scm new file mode 100644 index 00000000..7b6dacec --- /dev/null +++ b/module/util/color.scm @@ -0,0 +1,22 @@ +(define-module (util color) + ) + +;; Returns a color with good contrast to the given background color. +;; https://stackoverflow.com/questions/1855884/determine-font-color-based-on-background-color/1855903#1855903 +(define-public (calculate-fg-color c) + (catch #t + (lambda () + (define (str->num c n) (string->number (substring/shared c n (+ n 2)) 16)) + ;; (format (current-error-port) "COLOR = ~s~%" c) + (let ((r (str->num c 1)) + (g (str->num c 3)) + (b (str->num c 5))) + (if (< 1/2 (/ (+ (* 0.299 r) + (* 0.587 g) + (* 0.114 b)) + #xFF)) + "#000000" "#FFFFFF"))) + (lambda args + (format (current-error-port) "Error calculating foreground color?~%~s~%" args) + "#FF0000" + ))) |