adding true color ansi support

lib/chibi/term/ansi-test.sld

@@ -127,6 +127,7 @@
       (test-wrap-procedure   (rgb 5 5 5) "\x1B;[38;5;231mFOO\x1b;[39m")
       (test-wrap-procedure   (gray 0)    "\x1B;[38;5;232mFOO\x1b;[39m")
       (test-wrap-procedure   (gray 23)   "\x1B;[38;5;255mFOO\x1b;[39m")
+      (test-wrap-procedure   (rgb24 #xA6 #x7B #x5B) "\x1B;[38;2;166;123;91mFOO\x1b;[39m")
 
       (test-escape-procedure black-background-escape       "\x1b;[40m")
       (test-escape-procedure red-background-escape         "\x1b;[41m")

lib/chibi/term/ansi.scm

@@ -82,6 +82,26 @@
                  (number->string (+ gray-level 232))
                  "m"))
 
+;;> The true-color equivalent of \scheme{rgb-escape}. Return a string
+;;> consisting of an ANSI escape code to select the text color
+;;> specified by the \var{red-level}, \var{green-level}, and
+;;> \var{blue-level} arguments, each of which must be an exact integer
+;;> in the range [0, 255].
+
+(define (rgb24-escape red-level green-level blue-level)
+  (when (not (and (exact-integer? red-level) (<= 0 red-level 255)))
+    (error "invalid red-level value" red-level))
+  (when (not (and (exact-integer? green-level) (<= 0 green-level 255)))
+    (error "invalid green-level value" green-level))
+  (when (not (and (exact-integer? blue-level) (<= 0 blue-level 255)))
+    (error "invalid blue-level value" blue-level))
+  (string-append
+   "\x1B;[38;2;"
+   (number->string red-level) ";"
+   (number->string green-level) ";"
+   (number->string blue-level)
+   "m"))
+
 ;;> Return a string consisting of an ANSI escape code to select the
 ;;> default text color.
 
@@ -157,6 +177,13 @@
   (make-wrap-procedure (gray-escape gray-level)
                        (reset-color-escape)))
 
+;;> The true-color equivalent of \scheme{rbg}, extending the ranges
+;;> to [0, 255].
+
+(define (rgb24 red-level green-level blue-level)
+  (make-wrap-procedure (rgb24-escape red-level green-level blue-level)
+                       (reset-color-escape)))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define black-background-escape
@@ -214,6 +241,26 @@
                  (number->string (+ gray-level 232))
                  "m"))
 
+;;> The true-color equivalent of \scheme{rgb-background-escape}.
+;;> Return a string consisting of an ANSI escape code to select the
+;;> text color specified by the \var{red-level}, \var{green-level},
+;;> and \var{blue-level} arguments, each of which must be an exact
+;;> integer in the range [0, 255].
+
+(define (rgb24-background-escape red-level green-level blue-level)
+  (when (not (and (exact-integer? red-level) (<= 0 red-level 255)))
+    (error "invalid red-level value" red-level))
+  (when (not (and (exact-integer? green-level) (<= 0 green-level 255)))
+    (error "invalid green-level value" green-level))
+  (when (not (and (exact-integer? blue-level) (<= 0 blue-level 255)))
+    (error "invalid blue-level value" blue-level))
+  (string-append
+   "\x1B;[48;5;"
+   (number->string red-level) ";"
+   (number->string green-level) ";"
+   (number->string blue-level)
+   "m"))
+
 ;;> \procedure{(reset-background-color-escape)}
 ;;>
 ;;> Return a string consisting of an ANSI escape code to select the
@@ -291,6 +338,14 @@
   (make-wrap-procedure (gray-background-escape gray-level)
                        (reset-background-color-escape)))
 
+;;> The true-color equivalent of \scheme{rbg-background}, extending
+;;> the ranges to [0, 255].
+
+(define (rgb24-background red-level green-level blue-level)
+  (make-wrap-procedure
+   (rgb24-background-escape red-level green-level blue-level)
+   (reset-background-color-escape)))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;;> Return a string consisting of an ANSI escape code to select bold

lib/chibi/term/ansi.sld

@@ -5,6 +5,7 @@
    blue-escape cyan-escape magenta-escape white-escape
    rgb-escape 
    gray-escape
+   rgb24-escape 
    reset-color-escape
 
    black-background-escape red-background-escape
@@ -13,6 +14,7 @@
    magenta-background-escape white-background-escape
    rgb-background-escape
    gray-background-escape
+   rgb24-background-escape
    reset-background-color-escape
 
    black red yellow green
@@ -24,6 +26,7 @@
    negative
    rgb rgb-background
    gray gray-background
+   rgb24 rgb24-background
    bold-escape reset-bold-escape
    underline-escape reset-underline-escape
    negative-escape reset-negative-escape