Added constructor for hex color strings

src/Color.cpp

@@ -1,14 +1,9 @@
-//
-// Color.cpp
-// screensaver
-//
-// Created by Bob Polis at 2020-10-27
-// Copyright (c) 2020 SwiftCoder. All rights reserved.
-//
-
 #include "Color.hpp"
 #include <algorithm>
 #include <cmath>
+#include <stdexcept>
+#include <sstream>
+#include <iomanip>
 
 Color::Color(const RGB& rgb) : _rgb {rgb} {}
 
@@ -81,3 +76,23 @@ Color::operator HSB() const {
     hsb.b = rgb_max;
     return hsb;
 }
+
+Color::Color(const std::string& hex) {
+    if (hex[0] != '#') throw std::runtime_error {"invalid hex color - must start with '#'"};
+    if (hex.size() != 7) throw std::runtime_error {"invalid hex color - must be 7 chars"};
+    unsigned int val;
+
+    std::istringstream iss {hex.substr(1, 2)};
+    iss >> std::hex >> val;
+    _rgb.r = val / 256.0;
+
+    iss.str(hex.substr(3, 2));
+    iss.seekg(0);
+    iss >> std::hex >> val;
+    _rgb.g = val / 256.0;
+
+    iss.str(hex.substr(5, 2));
+    iss.seekg(0);
+    iss >> std::hex >> val;
+    _rgb.b = val / 256.0;
+}

src/Color.hpp

@@ -1,14 +1,8 @@
-//
-// Color.hpp
-// screensaver
-//
-// Created by Bob Polis at 2020-10-27
-// Copyright (c) 2020 SwiftCoder. All rights reserved.
-//
-
 #ifndef _Color_H_
 #define _Color_H_
 
+#include <string>
+
 struct RGB {
     double r;
     double g;
@@ -25,6 +19,7 @@ class Color {
     public:
         Color(const RGB& rgb);
         Color(const HSB& hsb);
+        Color(const std::string& hex);
 
         operator RGB() const { return _rgb; }
         operator HSB() const;