degesch: precompute the filtered color cube

1 files changed, 31 insertions, 25 deletions

diff --git a/degesch.c b/degesch.c
index 889d989..35dcce0 100644
--- a/degesch.c
+++ b/degesch.c
@@ -1363,6 +1363,9 @@ struct app_context
 
 	struct input input;                 ///< User interface
 
+	int *nick_palette;                  ///< A 256-color palette for nicknames
+	size_t nick_palette_len;            ///< Number of entries in nick_palette
+
 	bool awaiting_mirc_escape;          ///< Awaiting a mIRC attribute escape
 	char char_buf[MB_LEN_MAX + 1];      ///< Buffered multibyte char
 	size_t char_buf_len;                ///< How much of an MB char is buffered
@@ -1371,6 +1374,28 @@ struct app_context
 }
 *g_ctx;
 
+static int *
+filter_color_cube_for_acceptable_nick_colors (size_t *len)
+{
+	// This is a pure function and we don't use threads, static storage is fine
+	static int table[6 * 6 * 6];
+	size_t len_counter = 0;
+	for (int x = 0; x < 6 * 6 * 6; x++)
+	{
+		int r =  x / 36;
+		int g = (x / 6) % 6;
+		int b = (x % 6);
+
+		// Use the luma value of colours within the cube to filter colours that
+		// look okay-ish on terminals with both black and white backgrounds
+		double luma = 0.2126 * r / 6. + 0.7152 * g / 6. + 0.0722 * b / 6.;
+		if (luma >= .3 && luma <= .5)
+			table[len_counter++] = 16 + x;
+	}
+	*len = len_counter;
+	return table;
+}
+
 static void
 app_context_init (struct app_context *self)
 {
@@ -1407,6 +1432,9 @@ app_context_init (struct app_context *self)
 	free (encoding);
 
 	input_init (&self->input);
+
+	self->nick_palette =
+		filter_color_cube_for_acceptable_nick_colors (&self->nick_palette_len);
 }
 
 static void
@@ -2467,27 +2495,6 @@ formatter_parse_mirc (struct formatter *self, const char *s)
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-static int *
-filter_color_cube_for_acceptable_nick_colors (size_t *len)
-{
-	static int table[6 * 6 * 6];
-	size_t len_counter = 0;
-	for (int x = 0; x < 6 * 6 * 6; x++)
-	{
-		int r =  x / 36;
-		int g = (x / 6) % 6;
-		int b = (x % 6);
-
-		// Use the luma value of colours within the cube to filter colours that
-		// look okay-ish on terminals with both black and white backgrounds
-		double luma = 0.2126 * r / 6. + 0.7152 * g / 6. + 0.0722 * b / 6.;
-		if (luma >= .3 && luma <= .5)
-			table[len_counter++] = 16 + x;
-	}
-	*len = len_counter;
-	return table;
-}
-
 static void
 formatter_parse_nick (struct formatter *self, char *s)
 {
@@ -2499,10 +2506,9 @@ formatter_parse_nick (struct formatter *self, char *s)
 	if (color == COLOR_BLACK)
 		color = -1;
 
-	size_t len;
-	// TODO: precompute this table
-	int *colors = filter_color_cube_for_acceptable_nick_colors (&len);
-	color |= colors[siphash_wrapper (nick, strlen (nick)) % len] << 16;
+	// Use a color from the 256-color cube if available
+	color |= self->ctx->nick_palette[siphash_wrapper (nick,
+		strlen (nick)) % self->ctx->nick_palette_len] << 16;
 
 	// We always use the default color for ourselves
 	if (self->s && irc_is_this_us (self->s, nick))