Add palette object. Optimise matching colour in case where we chose the palette. In other cases, we still have to seach all the colours, but that doesn't ever seem to be used.

1 files changed, 89 insertions, 0 deletions

diff --git a/src/palette.c b/src/palette.c
new file mode 100644
index 0000000..eba95cd
--- /dev/null
+++ b/src/palette.c
@@ -0,0 +1,89 @@
+/*
+ * 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
+ */
+
+/** \file
+ * Palette (implementation).
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "palette.h"
+
+
+/** Create an empty palette object. */
+bool nsfb_palette_new(struct nsfb_palette_s **palette)
+{
+	*palette = malloc(sizeof(struct nsfb_palette_s));
+	if (*palette == NULL) {
+		return false;
+	}
+
+	(*palette)->type = NSFB_PALETTE_EMPTY;
+	(*palette)->last = 0;
+
+	return true;
+}
+
+/** Free a palette object. */
+void nsfb_palette_free(struct nsfb_palette_s *palette)
+{
+	if (palette != NULL)
+		free(palette);
+}
+
+/** Generate libnsfb 8bpp default palette. */
+void nsfb_palette_generate_nsfb_8bpp(struct nsfb_palette_s *palette)
+{
+	int rloop, gloop, bloop;
+	int loop = 0;
+	uint8_t r, g, b;
+
+	/* Build a linear 6-8-5 levels RGB colour cube palette.
+	 * This accounts for 240 colours */
+#define RLIM 6
+#define GLIM 8
+#define BLIM 5
+	for (rloop = 0; rloop < RLIM; rloop++) {
+		for (gloop = 0; gloop < GLIM; gloop++) {
+			for (bloop = 0; bloop < BLIM; bloop++) {
+				r = ((rloop * 255 * 2) + RLIM - 1) /
+						(2 * (RLIM - 1));
+				g = ((gloop * 255 * 2) + GLIM - 1) /
+						(2 * (GLIM - 1));
+				b = ((bloop * 255 * 2) + BLIM - 1) /
+						(2 * (BLIM - 1));
+
+				palette->data[loop] = r | g << 8 | b << 16;
+				loop++;
+			}
+		}
+	}
+#undef RLIM
+#undef GLIM
+#undef BLIM
+
+	/* Should have 240 colours set */
+	assert(loop == 240);
+
+	/* Fill index 240 to index 255 with grayscales */
+	/* Note: already have full black and full white from RGB cube */
+	for (; loop < 256; loop++) {
+		int ngray = loop - 240 + 1;
+		r = ngray * 15; /* 17*15 = 255 */
+
+		g = b = r;
+
+		palette->data[loop] = r | g << 8 | b << 16;
+	}
+
+	/* Set palette details */
+	palette->type = NSFB_PALETTE_NSFB_8BPP;
+	palette->last = 255;
+}