Allow specifying lighter or darker variants of built-in colors.

Color.cpp

@@ -4,6 +4,9 @@
 #include <cstdlib>
 #include <map>
 #include <string>
+#include <cstring>
+#include <sstream>
+#include <iomanip>
 #include <cctype>
 #include "Color.h"
 
@@ -47,32 +50,38 @@ ColorTable colorTable;
 //	-1: allow alpha but ignore - set to to 255 (0xff)
 Color::Color(std::string color, int alpha)
 {
-	if (color[0] != '#') {
+	size_t pos = color.find_first_of("+-");
-		int l = color.length();
+	std::string basecolor = color.substr(0, pos);
+	std::string colormod;
+	if (pos != std::string::npos)
+		colormod = color.substr(pos);
+	do {
+		if (basecolor[0] != '#') {
+			int l = basecolor.length();
 			for (int i = 0; i < l; i++)
-			color[i] = tolower(color[i]);
+				basecolor[i] = tolower(basecolor[i]);
-		if (colorTable.count(color) > 0) {
+			if (colorTable.count(basecolor) > 0) {
-			*this = colorTable[color];
+				*this = colorTable[basecolor];
-			return;
+				break;
 			}
 			throw std::runtime_error(std::string("Symbolic color '") + color + "' not known, or color does not begin with #");
 		}
-	if (std::string::npos != color.find_first_not_of("0123456789abcdefABCDEF",1)) {
+		if (std::string::npos != basecolor.find_first_not_of("0123456789abcdefABCDEF",1)) {
 			throw std::runtime_error("Color value has invalid digits (expected: [0-9a-zA-Z])");
 		}
 		if (alpha) {
-		if (color.length() != 4 && color.length() != 5 && color.length() != 7 && color.length() != 9)
+			if (basecolor.length() != 4 && basecolor.length() != 5 && basecolor.length() != 7 && basecolor.length() != 9)
-			throw std::runtime_error("Color not in the expected format (#xxx, #xxxx, #xxxxxx or #xxxxxxxx)");
+				throw std::runtime_error(std::string("Color '") + color + "' not in the expected format (#xxx, #xxxx, #xxxxxx or #xxxxxxxx)");
 		}
 		else {
-		if (color.length() == 5 || color.length() == 9)
+			if (basecolor.length() == 5 || basecolor.length() == 9)
-			throw std::runtime_error("Color not in the expected format (#xxx or #xxxxxx) - alpha not allowed");
+				throw std::runtime_error(std::string("Color '") + color + "' not in the expected format (#xxx or #xxxxxx) - alpha not allowed");
-		if (color.length() != 4 && color.length() != 7)
+			if (basecolor.length() != 4 && basecolor.length() != 7)
-			throw std::runtime_error("Color not in the expected format (#xxx or #xxxxxx)");
+				throw std::runtime_error(std::string("Color '") + color + "' not in the expected format (#xxx or #xxxxxx)");
 		}
-	unsigned col = strtoul(color.c_str() + 1, NULL, 16);
+		unsigned col = strtoul(basecolor.c_str() + 1, NULL, 16);
-	if (color.length() < 6) {
+		if (basecolor.length() < 6) {
-		if (color.length() == 5)
+			if (basecolor.length() == 5)
 				a = (col >> 12) & 0x0f;
 			else
 				a = 0x0f;
@@ -85,7 +94,7 @@ Color::Color(std::string color, int alpha)
 			b |= b << 4;
 		}
 		else {
-		if (color.length() == 9)
+			if (basecolor.length() == 9)
 				a = (col >> 24) & 0xff;
 			else
 				a = 0xff;
@@ -95,5 +104,78 @@ Color::Color(std::string color, int alpha)
 		}
 		if (alpha <= 0)
 			a = 0xff;
+	} while(false);
+	if (colormod.length() == 0)
+		return;
+	std::istringstream iss(colormod);
+	iss >> std::ws;
+	while (!iss.eof()) {
+		double w;
+		char operation;
+		char ccode='w';
+		iss >> operation;
+		iss >> ccode;
+		iss >> w >> std::ws;
+		if (w > 1)
+			w = w / 255;
+		if (!strchr("+-",operation) || !strchr("wkrgbcmy", ccode) || w < 0 || w > 1 || iss.fail())
+			throw std::runtime_error(std::string("Invalid color modification(s) (") + color + "); expected one or more of [+-][wkrgbcmy]<n> (n = 0..1)");
+		double v;
+		if (operation == '+' || operation == '-') {
+			// Mix in a color
+			int mixr = r;
+			int mixg = g;
+			int mixb = b;
+			if (operation == '+') {
+				if (ccode == 'w')
+					mixr = mixg = mixb = 255;
+				else if (operation == 'k')
+					mixr = mixg = mixb = 0;
+				else if (ccode == 'r')
+					mixr = 255;
+				else if (ccode == 'g')
+					mixg = 255;
+				else if (ccode == 'b')
+					mixb = 255;
+				else if (ccode == 'c')
+					mixg = mixb = 255;
+				else if (ccode == 'm')
+					mixr = mixb = 255;
+				else if (ccode == 'y')
+					mixr = mixg = 255;
+			}
+			else {
+				if (ccode == 'w')
+					mixr = mixg = mixb = 0;
+				else if (operation == 'k')
+					mixr = mixg = mixb = 255;
+				else if (ccode == 'r')
+					mixr = 0;
+				else if (ccode == 'g')
+					mixg = 0;
+				else if (ccode == 'b')
+					mixb = 0;
+				else if (ccode == 'c')
+					mixg = mixb = 0;
+				else if (ccode == 'm')
+					mixr = mixb = 0;
+				else if (ccode == 'y')
+					mixr = mixg = 0;
+			}
+
+			v = r * (1 - w) + mixr * w;
+			if (v < 0) v = 0;
+			else if (v > 255) v = 255;
+			r = int(v + 0.5);
+			v = g * (1 - w) + mixg * w;
+			if (v < 0) v = 0;
+			else if (v > 255) v = 255;
+			g = int(v + 0.5);
+			v = b * (1 - w) + mixb * w;
+			if (v < 0) v = 0;
+			else if (v > 255) v = 255;
+			b = int(v + 0.5);
+		}
+	}
 }
 

mapper.cpp

@@ -113,6 +113,8 @@ void usage()
 			"\t\tyellow, magenta, fuchsia, cyan, aqua,\n"
 			"\t\torange, chartreuse, pink, violet, springgreen, azure\n"
 			"\t\tbrown (= 50% orange)\n"
+			"\tAs well as <color>[+-][wkrgbcmy]<n>, where n = 0.0..1.0 (or 1.00001 .. 255)\n"
+			"\t\t[+-][wkrgbcmy]<n> mixes in or out white, black, red, green, blue, cyan, magenta, yellow\n"
 			"Geometry formats:\n"
 			"\t<width>x<heigth>[+|-<xoffset>+|-<yoffset>]           (dimensions and corner)\n"
 			"\t<xoffset>,<yoffset>+<width>+<height>                 (corner and dimensions)\n"