1 files changed, 111 insertions, 0 deletions
diff --git a/include/palette.h b/include/palette.h
new file mode 100644
index 0000000..845c1bc
--- /dev/null
+++ b/include/palette.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2012 Michael Drake <tlsa@netsurf-browser.org>
+ *
+ * This file is part of libnsfb, http://www.netsurf-browser.org/
+ * Licenced under the MIT License,
+ *                http://www.opensource.org/licenses/mit-license.php
+ *
+ * This is the *internal* interface for the cursor. 
+ */
+
+#ifndef PALETTE_H
+#define PALETTE_H 1
+
+#include <stdint.h>
+#include <limits.h>
+
+#include "libnsfb.h"
+#include "libnsfb_plot.h"
+
+enum nsfb_palette_type_e {
+	NSFB_PALETTE_EMPTY,     /**< empty palette object */
+	NSFB_PALETTE_NSFB_8BPP, /**< libnsfb's own 8bpp palette */
+	NSFB_PALETTE_OTHER      /**< any other palette  */
+};
+
+struct nsfb_palette_s {
+	enum nsfb_palette_type_e type; /**< Palette type */
+	uint8_t last; /**< Last used palette index */
+	nsfb_colour_t data[256]; /**< Palette for index modes */
+};
+
+/** Create an empty palette object. */
+bool nsfb_palette_new(struct nsfb_palette_s **palette);
+
+/** Free a palette object. */
+void nsfb_palette_free(struct nsfb_palette_s *palette);
+
+/** Generate libnsfb 8bpp default palette. */
+void nsfb_palette_generate_nsfb_8bpp(struct nsfb_palette_s *palette);
+
+
+static inline uint8_t nsfb_palette_best_match(
+		const struct nsfb_palette_s *palette,
+		nsfb_colour_t c)
+{
+	uint8_t best_col = 0;
+
+	nsfb_colour_t palent;
+	int col;
+	int dr, dg, db; /* delta red, green blue values */
+
+	int cur_distance;
+	int best_distance = INT_MAX;
+
+	switch (palette->type) {
+	case NSFB_PALETTE_NSFB_8BPP:
+		/* Index into colour cube part */
+		dr = ((( c        & 0xFF) * 5) + 128) / 256;
+		dg = ((((c >>  8) & 0xFF) * 7) + 128) / 256;
+		db = ((((c >> 16) & 0xFF) * 4) + 128) / 256;
+		col = 40 * dr + 5 * dg + db;
+
+		palent = palette->data[col];
+		dr = ( c        & 0xFF) - ( palent        & 0xFF);
+		dg = ((c >>  8) & 0xFF) - ((palent >> 8 ) & 0xFF);
+		db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
+		cur_distance = (dr * dr) + (dg * dg) + (db * db);
+
+		best_col = col;
+		best_distance = cur_distance;
+
+		/* Index into grayscale part */
+		col = (( c        & 0xFF) +
+		       ((c >>  8) & 0xFF) +
+		       ((c >> 16) & 0xFF) + (45 / 2)) / (15 * 3) - 1 + 240;
+		palent = palette->data[col];
+
+		dr = ( c        & 0xFF) - ( palent        & 0xFF);
+		dg = ((c >>  8) & 0xFF) - ((palent >>  8) & 0xFF);
+		db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
+		cur_distance = (dr * dr) + (dg * dg) + (db * db);
+		if (cur_distance < best_distance) {
+			best_distance = cur_distance;
+			best_col = col;
+		}
+		break;
+
+	case NSFB_PALETTE_OTHER:
+		/* Try all colours in palette */
+		for (col = 0; col <= palette->last; col++) {
+			palent = palette->data[col];
+
+			dr = ( c        & 0xFF) - ( palent        & 0xFF);
+			dg = ((c >>  8) & 0xFF) - ((palent >>  8) & 0xFF);
+			db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
+			cur_distance = (dr * dr) + (dg * dg) + (db * db);
+			if (cur_distance < best_distance) {
+				best_distance = cur_distance;
+				best_col = col;
+			}
+		}
+		break;
+
+	default:
+		break;
+	}
+
+        return best_col;
+}
+
+#endif /* PALETTE_H */