fix(packages): Stricter color parsing and improved color documentation

core/colorparser.lua

@@ -151,27 +151,38 @@ local colorsRGB = {
 
 local colorparser = function (col)
   local r, g, b, c, m, y, k, l
-  if colorsRGB[col] then
-    c = colorsRGB[col]
-    return { r = c[1] / 255, g = c[2] / 255, b = c[3] / 255 }
+  if not col or type(col) ~= "string" then
+    SU.error("Not a color specification string ("..tostring(col)..")")
   end
-  r, g, b = col:match("#(%x%x)(%x%x)(%x%x)")
+  local named = colorsRGB[string.lower(col)]
+  if named then
+    return { r = named[1] / 255, g = named[2] / 255, b = named[3] / 255 }
+  end
+  r, g, b = col:match("^#(%x%x)(%x%x)(%x%x)$")
   if r then
     return { r = tonumber("0x"..r)/255, g = tonumber("0x"..g)/255, b = tonumber("0x"..b)/255 }
   end
-  r, g, b = col:match("#(%x)(%x)(%x)")
+  r, g, b = col:match("^#(%x)(%x)(%x)$")
   if r then
     return { r = tonumber("0x"..r)/15, g = tonumber("0x"..g)/15, b = tonumber("0x"..b)/15 }
   end
-  c, m, y, k = col:match("(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)")
+  c, m, y, k = col:match("^(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)$")
   if c then
     return { c = tonumber(c)/255, m = tonumber(m)/255, y = tonumber(y)/255, k = tonumber(k)/255 }
   end
-  r, g, b = col:match("(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)")
+  c, m, y, k = col:match("^(%d+%.?%d*)%%%s+(%d+%.?%d*)%%%s+(%d+%.?%d*)%%%s+(%d+%.?%d*)%%$")
+  if c then
+    return { c = tonumber(c)/100, m = tonumber(m)/100, y = tonumber(y)/100, k = tonumber(k)/100 }
+  end
+  r, g, b = col:match("^(%d+%.?%d*)%s+(%d+%.?%d*)%s+(%d+%.?%d*)$")
   if r then
     return { r = tonumber(r)/255, g = tonumber(g)/255, b = tonumber(b)/255 }
   end
-  l = col:match("(%d+.?%d*)")
+  r, g, b = col:match("^(%d+%.?%d*)%%%s+(%d+%.?%d*)%%%s+(%d+%.?%d*)%%$")
+  if r then
+    return { r = tonumber(r)/100, g = tonumber(g)/100, b = tonumber(b)/100 }
+  end
+  l = col:match("^(%d+.?%d*)$")
   if l then
     return { l = tonumber(l)/255 }
   end

packages/color/init.lua

@@ -20,12 +20,22 @@ The \autodoc:package{color} package allows you to temporarily change the color o
 (virtual) ink that SILE uses to output text and rules. The package provides
 a \autodoc:command{\color} command which takes one parameter,
 \autodoc:parameter{color=<color specification>}, and typesets
-its argument in that color. The color specification is the same as HTML:
-it can be a RGB color value in \code{#xxx} or \code{#xxxxxx} format, where \code{x}
-represents a hexadecimal digit (\code{#000} is black, \code{#fff} is white,
-\code{#f00} is red and so on), or it can be one of the HTML and CSS named colors.
+its argument in that color.
 
-\note{The HTML and CSS named colors can be found at \code{http://dev.w3.org/csswg/css-color/#named-colors}.}
+The color specification is one of the following:
+\begin{itemize}
+\item{A RGB color in \code{#xxx} or \code{#xxxxxx} format, where \code{x}
+     represents a hexadecimal digit, as often seen in HTML/CSS (\code{#000} is
+     black, \code{#fff} is white, \code{#f00} is red and so on);}
+\item{A RGB color as a series of three numeric values between 0 and 255
+    (e.g. \code{0 0 139} is a dark blue) or as three percentages;}
+\item{A CMYK color as a series of four numeric values between 0 and 255
+    or as four percentages;}
+\item{A grayscale color as a numeric value between 0 and 255;}
+\item{A (case-insensitive) named color, as one of the 148 keywords defined
+    in the CSS Color Module Level 4. (Named colors resolve to RGB
+    in the actual output.)}
+\end{itemize}
 
 So, for example, \color[color=red]{this text is typeset with \autodoc:command{\color[color=red]{…}}}.
 

spec/colorparser_spec.lua

@@ -0,0 +1,43 @@
+SILE = require("core.sile")
+SU.warn = function () end
+
+describe("The color parser", function()
+  local parse = SILE.colorparser
+  local rebecca = {
+    b = 0.6,
+    g = 0.2,
+    r = 0.4
+  }
+  local reddish = {
+    c = 0,
+    k = 0.3,
+    m = 0.81,
+    y = 0.81
+  }
+  it("should return the correct RGB values for a named color", function()
+    assert.is.same(parse("rebeccapurple"), rebecca)
+    assert.is.same(parse("RebeccaPurple"), rebecca)
+  end)
+  it("should return the correct RGB values for a hexadecimal specification", function()
+    assert.is.same(parse("#663399"), rebecca)
+    assert.is.same(parse("#639"), rebecca)
+  end)
+  it("should return the correct RGB values for a series of 3 numbers or percentages", function()
+    assert.is.same(parse("102 51 153"), rebecca)
+    assert.is.same(parse("40% 20% 60%"), rebecca)
+  end)
+  it("should return the correct CMYK values for a series of 4 numbers or percentages", function()
+    assert.is.same(parse("0% 81% 81% 30%"), reddish)
+    assert.is.same(parse("0 206.55 206.55 76.5"), reddish)
+  end)
+  it("should return the correct grayscale value for single number", function()
+    assert.is.same(parse("204"), { l = 0.8 })
+  end)
+
+  it("error if unable to parse", function()
+    assert.has.errors(function () parse("not_a_color") end)
+    assert.has.errors(function () parse(nil) end)
+    assert.has.errors(function () parse("") end)
+  end)
+end)
+