Add GIMP palettes support, refactoring

You can now use GIMP palette file as a colormap, by using its filename as a color.
Add the well known Matlab jet72 palette (jet72.gpl).

Group functions in sections.

colout/colout.py

@@ -13,9 +13,50 @@ import glob
 import math
 import importlib
 
-###########
+###############################################################################
-# Library #
+# Ressource parsing helpers
-###########
+###############################################################################
+
+def parse_gimp_palette( filename ):
+    """
+    Parse the given filename as a GIMP palette (.gpl)
+
+    Return the filename (without path and extension) and a list of ordered
+    colors.
+    Generally, the colors are RGB triplets, thus this function returns:
+        (name, [ [R0,G0,B0], [R1,G1,B1], ... , [RN,GN,BN] ])
+    """
+
+    fd = open(filename)
+    # remove path and extension, only keep the file name itself
+    name = os.path.splitext( os.path.basename(filename ))[0]
+
+    # The first .gpl line is a header
+    assert( fd.readline().strip() == "GIMP Palette" )
+
+    # Then the full name of the palette
+    long_name = fd.readline().strip()
+
+    # Then the columns number.
+    # split on colon, take the second argument as an int
+    columns = int( fd.readline().strip().split(":")[1].strip() )
+
+    # Then the colors themselves.
+    palette = []
+    for line in fd:
+        # skip lines with only a comment
+        if re.match("^\s*#.*$", line ):
+            continue
+        # decode the columns-ths codes. Generally [R G B] followed by a comment
+        colors = [ int(c) for c in line.split()[:columns] ]
+        palette.append( colors )
+
+    return name,palette
+
+
+###############################################################################
+# Global variables
+###############################################################################
 
 # Available styles
 styles = {
@@ -30,37 +71,6 @@ colors = {
     "magenta": 5, "cyan": 6, "white": 7, "none": -1
 }
 
-ansi_min = 16
-ansi_max = 232
-
-def rgb_rainbow( x, freq = 1.0/(256.0/math.pi) ):
-    scope = (ansi_max - ansi_min)/2.0
-    red   = ansi_min + scope * (1+math.sin( 2*freq*x + math.pi/2 ))
-    green = ansi_min + scope * (1+math.sin( 2*freq*x - math.pi/2 ))
-    blue  = ansi_min + scope * (1+math.sin(   freq*x - math.pi/2 ))
-    return ( red, green, blue )
-
-
-def rgb_to_ansi( red, green, blue ):
-
-    offset = 42.5
-    is_gray = True
-    while is_gray:
-        if red < offset or green < offset or blue < offset:
-            all_gray = red < offset and green < offset and blue < offset
-            is_gray = False
-        offset += 42.5
-
-    if all_gray:
-        val = ansi_max + round( (red + green + blue)/33.0 )
-        return int(val)
-    else:
-        val = ansi_min
-        for color,modulo in zip( [red, green, blue], [6*6, 6, 1] ):
-            val += round(6.0 * (color / 256.0)) * modulo
-        return int(val)
-
-
 rainbow = ["magenta", "blue", "cyan", "green", "yellow", "red"]
 colormap = rainbow  # default colormap to rainbow
 colormap_idx = 0
@@ -70,15 +80,40 @@ scale = (0,100)
 # Escaped end markers for given color modes
 endmarks = {8: ";", 256: ";38;5;"}
 
+ansi_min = 16
+ansi_max = 232
+
+def rgb_rainbow( x, freq = 1.0/(256.0/math.pi) ):
+    """Analytical expression of a n-colors rainbow colormap"""
+    scope = (ansi_max - ansi_min)/2.0
+    red   = ansi_min + scope * (1+math.sin( 2*freq*x + math.pi/2 ))
+    green = ansi_min + scope * (1+math.sin( 2*freq*x - math.pi/2 ))
+    blue  = ansi_min + scope * (1+math.sin(   freq*x - math.pi/2 ))
+    return ( red, green, blue )
+
+
+###############################################################################
+# Load available extern ressources
+###############################################################################
+
 # load available themes
 themes = {}
 themes_dir=os.path.dirname(os.path.realpath(__file__))
 os.chdir( themes_dir )
+
 for f in glob.iglob("colout_*.py"):
     module = ".".join(f.split(".")[:-1]) # remove extension
     name = "_".join(module.split("_")[1:]) # remove the prefix
     themes[name] = importlib.import_module(module)
 
+# load available colormaps (GIMP palettes format)
+colormaps = {}
+for p in glob.iglob("*.gpl"):
+    name,palette = parse_gimp_palette(p)
+    if name in colormaps:
+        raise Exception('Duplicated palette filename: %s' % name)
+    colormaps[name] = palette
+
 # load available pygments lexers
 lexers = []
 try:
@@ -98,6 +133,30 @@ else:
     lexers.sort()
 
 
+###############################################################################
+# Library
+###############################################################################
+
+def rgb_to_ansi( red, green, blue ):
+    """Convert a RGB color to its closest 256-colors ANSI index"""
+    offset = 42.5
+    is_gray = True
+    while is_gray:
+        if red < offset or green < offset or blue < offset:
+            all_gray = red < offset and green < offset and blue < offset
+            is_gray = False
+        offset += 42.5
+
+    if all_gray:
+        val = ansi_max + round( (red + green + blue)/33.0 )
+        return int(val)
+    else:
+        val = ansi_min
+        for color,modulo in zip( [red, green, blue], [6*6, 6, 1] ):
+            val += round(6.0 * (color / 256.0)) * modulo
+        return int(val)
+
+
 def colorin(text, color="red", style="normal"):
     """
     Return the given text, surrounded by the given color ASCII markers.
@@ -162,6 +221,16 @@ def colorin(text, color="red", style="normal"):
         else:
             colormap_idx = 0
 
+    elif color in colormaps.keys():
+        mode = 256
+        color_nb = rgb_to_ansi( *colormaps[color][colormap_idx] )
+        color_code = str( color_nb )
+
+        if colormap_idx < len(colormaps[color]):
+            colormap_idx += 1
+        else:
+            colormap_idx = 0
+
     elif color == "scale":
         try:
             import babel.numbers as bn

colout/jet72.gpl

@@ -0,0 +1,77 @@
+GIMP Palette
+Name: MATLAB Jet (72)
+Columns: 3
+#
+  0   0 127 0
+  0   0 127 #1
+  0   0 141 #2
+  0   0 155 #3
+  0   0 169 #4
+  0   0 183 #5
+  0   0 198 #6
+  0   0 212 #7
+  0   0 226 #8
+  0   0 240 #9
+  0   0 255 #10
+  0  14 255 #11
+  0  28 255 #12
+  0  42 255 #13
+  0  56 255 #14
+  0  70 255 #15
+  0  84 255 #16
+  0  98 255 #17
+  0 112 255 #18
+  0 127 255 #19
+  0 141 255 #20
+  0 155 255 #21
+  0 169 255 #22
+  0 183 255 #23
+  0 198 255 #24
+  0 212 255 #25
+  0 226 255 #26
+  0 240 255 #27
+  0 255 255 #28
+ 14 255 240 #29
+ 28 255 226 #30
+ 42 255 212 #31
+ 56 255 198 #32
+ 70 255 183 #33
+ 84 255 169 #34
+ 98 255 155 #35
+112 255 141 #36
+127 255 127 #37
+141 255 112 #38
+155 255  98 #39
+169 255  84 #40
+183 255  70 #41
+198 255  56 #42
+212 255  42 #43
+226 255  28 #44
+240 255  14 #45
+255 255   0 #46
+255 240   0 #47
+255 226   0 #48
+255 212   0 #49
+255 198   0 #50
+255 183   0 #51
+255 169   0 #52
+255 155   0 #53
+255 141   0 #54
+255 127   0 #55
+255 112   0 #56
+255  98   0 #57
+255  84   0 #58
+255  70   0 #59
+255  56   0 #60
+255  42   0 #61
+255  28   0 #62
+255  14   0 #63
+255   0   0 #64
+240   0   0 #65
+226   0   0 #66
+212   0   0 #67
+198   0   0 #68
+183   0   0 #69
+169   0   0 #70
+155   0   0 #71
+141   0   0 #72