Codechange: Give sprite encoders a hint which colour components of a sprite are filled with useful information.

src/spriteloader/spriteloader.hpp

@@ -11,11 +11,21 @@
 #define SPRITELOADER_HPP
 
 #include "../core/alloc_type.hpp"
+#include "../core/enum_type.hpp"
 #include "../gfx_type.h"
 
 struct Sprite;
 typedef void *AllocatorProc(size_t size);
 
+/** The different colour components a sprite can have. */
+enum SpriteColourComponent {
+	SCC_RGB   = 1 << 0, ///< Sprite has RGB.
+	SCC_ALPHA = 1 << 1, ///< Sprite has alpha.
+	SCC_PAL   = 1 << 2, ///< Sprite has palette data.
+	SCC_MASK  = SCC_RGB | SCC_ALPHA | SCC_PAL, ///< Mask of valid colour bits.
+};
+DECLARE_ENUM_AS_BIT_SET(SpriteColourComponent)
+
 /** Interface for the loader of our sprites. */
 class SpriteLoader {
 public:
@@ -40,6 +50,7 @@ public:
 		int16 x_offs;                    ///< The x-offset of where the sprite will be drawn
 		int16 y_offs;                    ///< The y-offset of where the sprite will be drawn
 		SpriteType type;                 ///< The sprite type
+		SpriteColourComponent colours;   ///< The colour components of the sprite with useful information.
 		SpriteLoader::CommonPixel *data; ///< The sprite itself
 
 		/**