diff -r 52e10e8d88cc -r 1a4342d80de7 src/colors.h
--- a/src/colors.h	Wed Jun 08 19:33:00 2022 +0300
+++ b/src/colors.h	Wed Jun 08 20:41:21 2022 +0300
@@ -20,19 +20,6 @@
 #include <QColor>
 #include "main.h"
 
-namespace ldraw
-{
-	struct Color;
-	struct ColorDefinition;
-	class ColorTable;
-	Color directColor(const QColor& color);
-	bool isDirectColor(Color color);
-	QColor directColorFace(Color color);
-	QColor colorFace(Color color, const ColorTable& colorTable);
-	QColor colorEdge(Color color, const ColorTable& colorTable);
-	QString colorDisplayName(Color color, const ColorTable& colorTable);
-}
-
 /**
  * @brief Represents an LDraw color index (e.g 16, 24, ...)
  * 
@@ -52,64 +39,77 @@
  * LDConfig.ldr). Since this structure only contains an integer, it should be
  * passed by value to functions instead of l-value reference.
  */
-struct ldraw::Color
+struct ColorIndex
 {
 	qint32 index = 0;
-	constexpr auto operator<=>(const Color&) const = default;
+	constexpr auto operator<=>(const ColorIndex&) const = default;
 };
 
-Q_DECLARE_METATYPE(ldraw::Color)
-QDataStream& operator<<(QDataStream&, ldraw::Color);
-QDataStream& operator>>(QDataStream&, ldraw::Color&);
-
-namespace ldraw
-{
-	static constexpr Color MAIN_COLOR {16};
-	static constexpr Color EDGE_COLOR {24};
-}
+Q_DECLARE_METATYPE(ColorIndex)
+static constexpr ColorIndex MAIN_COLOR {16};
+static constexpr ColorIndex EDGE_COLOR {24};
 
 /**
  * @brief Contains the information about a specific color
  */
-struct ldraw::ColorDefinition
+struct ColorDefinition
 {
-	/**
-	 * @brief The face color. This is the color used for most objects.
-	 * This is also used for the polygons of a subfile reference.
-	 */
+	//! @brief The face color. This is the color used for most objects.
 	QColor faceColor;
-	/**
-	 * @brief The edge color, used for the edge lines of a subfile reference.
-	 * Note that edges using a color actually use the face color. LDraw standards
-	 * require edges to use color 24, however.
-	 */
+	//! @brief The edge color, used for the edge lines of a subfile reference.
+	//! Note that edges using a color actually use the face color. LDraw standards
+	//! require edges to use color 24, however.
 	QColor edgeColor;
-	/**
-	 * @brief Name of the color
-	 */
+	//! @brief Name of the color
 	QString name;
-	/**
-	 * @brief A version of the name that can be shown to the user.
-	 */
+	//! @brief A version of the name that can be shown to the user.
 	QString displayName;
 };
 
-/**
- * @brief Reads LDConfig.ldr and contains color table information for lookup purposes.
- */
-class ldraw::ColorTable
+//extern const ColorDefinition unknownColor;
+using ColorTable = std::map<ColorIndex, ColorDefinition>;
+std::optional<ColorTable> loadColorTable(QIODevice& device, QTextStream& errors);
+qreal luma(const QColor& color);
+ColorIndex directColor(const QColor& color);
+std::optional<QColor> colorFace(ColorIndex color, const ColorTable& colorTable);
+std::optional<QColor> colorEdge(ColorIndex color, const ColorTable& colorTable);
+std::optional<QString> colorDisplayName(ColorIndex color, const ColorTable& colorTable);
+QDataStream& operator<<(QDataStream&, ColorIndex);
+QDataStream& operator>>(QDataStream&, ColorIndex&);
+
+//! @brief Calculates the luma-value for the given color.
+//! @details c.f. https://en.wikipedia.org/wiki/Luma_(video)
+template<typename T>
+constexpr T luma(T r, T g, T b)
+{
+	return 0.2126 * r + 0.7152 * g + 0.0722 * b;
+}
+
+//! @brief Checks whether or not the specified color index is a direct color
+constexpr bool isDirectColor(ColorIndex color)
 {
-public:
-	void clear();
-	Result load(QIODevice& device, QTextStream& errors);
-	const ColorDefinition& operator[](Color index) const;
-	static const ColorDefinition unknownColor;
-	auto begin() const { return this->definitions.begin(); }
-	auto end() const { return this->definitions.end(); }
-	int size() const;
-private:
-	void loadColorFromString(const QString& string);
-	std::map<qint32, ColorDefinition> definitions;
-};
+	return color.index >= 0x2000000;
+}
+
+//! @brief Returns a direct color index that codes the specified color value
+constexpr ColorIndex directColor(int r, int g, int b)
+{
+	return ColorIndex{0x2000000 | (r << 16) | (g << 8) | b};
+}
 
-double luma(const QColor& color);
+//! @brief Extracts the r, g and b color channel values from a direct color
+//! index. Returns a default-constructed QColor in case a non-direct color is
+//! given.
+constexpr std::array<int, 3> directColorRgb(ColorIndex color)
+{
+	return {
+		(color.index >> 16) & 0xff,
+		(color.index >> 8) & 0xff,
+		color.index & 0xff
+	};
+}
+
+namespace ldraw
+{
+	using Color = ColorIndex;
+}