xF: make xC nick colors just work

Colour mapping still suffers, just not as heavily.

README.adoc

@@ -37,7 +37,8 @@ image::xP.webp[align="center"]
 xF
 --
 The hybrid terminal/X11 frontend for 'xC'.  It has simplified word wrapping,
-and X11 doesn't support text selection.  This frontend is perfect for testing.
+limited colour support, and X11 doesn't support text selection.
+This frontend is perfect for testing.
 
 xA, xT, xW, xM
 --------------

common.c

@@ -31,6 +31,7 @@
 
 #include "liberty/liberty.c"
 #include <arpa/inet.h>
+#include <math.h>
 #include <netinet/tcp.h>
 
 static void
@@ -108,6 +109,35 @@ tokenize_host_port (char *address, const char **port)
 	return address;
 }
 
+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 < (int) N_ELEMENTS (table); x++)
+	{
+		int r =  x / 36;
+		int g = (x / 6) % 6;
+		int b = (x % 6);
+
+		// The first step is 95/255, the rest are 40/255,
+		// as an approximation we can double the first step
+		double linear_R = pow ((r + !!r) / 6., 2.2);
+		double linear_G = pow ((g + !!g) / 6., 2.2);
+		double linear_B = pow ((b + !!b) / 6., 2.2);
+
+		// Use the relative luminance of colours within the cube to filter
+		// colours that look okay-ish on terminals with both black and white
+		// backgrounds (use the test-nick-colors script to calibrate)
+		double Y = 0.2126 * linear_R + 0.7152 * linear_G + 0.0722 * linear_B;
+		if (Y >= .25 && Y <= .4)
+			table[len_counter++] = 16 + x;
+	}
+	*len = len_counter;
+	return table;
+}
+
 // --- To be moved to liberty --------------------------------------------------
 
 #define LIST_FOR_EACH_REVERSED(type, iter, tail)                               \

test-nick-colors

@@ -9,7 +9,7 @@ export example=$(
 	#define N_ELEMENTS(a) (sizeof (a) / sizeof ((a)[0]))
 
 	$(perl -0777 -ne 'print $& if /^.*?\nfilter_color(?s:.*?)^}$/m' \
-		"$(dirname "$0")"/xC.c)
+		"$(dirname "$0")"/common.c)
 
 	void main () {
 		size_t len = 0;

xC.c

@@ -56,7 +56,6 @@ enum
 #include "xD-replies.c"
 #include "xC-proto.c"
 
-#include <math.h>
 #include <langinfo.h>
 #include <locale.h>
 #include <pwd.h>
@@ -2137,35 +2136,6 @@ static struct ispect_field g_ctx_ispect[] =
 	{}
 };
 
-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 < (int) N_ELEMENTS (table); x++)
-	{
-		int r =  x / 36;
-		int g = (x / 6) % 6;
-		int b = (x % 6);
-
-		// The first step is 95/255, the rest are 40/255,
-		// as an approximation we can double the first step
-		double linear_R = pow ((r + !!r) / 6., 2.2);
-		double linear_G = pow ((g + !!g) / 6., 2.2);
-		double linear_B = pow ((b + !!b) / 6., 2.2);
-
-		// Use the relative luminance of colours within the cube to filter
-		// colours that look okay-ish on terminals with both black and white
-		// backgrounds (use the test-nick-colors script to calibrate)
-		double Y = 0.2126 * linear_R + 0.7152 * linear_G + 0.0722 * linear_B;
-		if (Y >= .25 && Y <= .4)
-			table[len_counter++] = 16 + x;
-	}
-	*len = len_counter;
-	return table;
-}
-
 static bool
 app_iconv_open (iconv_t *target, const char *to, const char *from)
 {

xF.c

@@ -23,7 +23,6 @@
 #include "xC-proto.c"
 
 #include <locale.h>
-#include <math.h>
 
 #ifdef WITH_X11
 #define LIBERTY_XUI_WANT_X11
@@ -340,7 +339,8 @@ enum app_attribute
 	ATTRIBUTE_COUNT,
 };
 
-static struct attrs g_attrs[ATTRIBUTE_COUNT] =
+static size_t g_attrs_len = ATTRIBUTE_COUNT;
+static struct attrs g_attrs[256] =
 {
 #define XX(name, fg, bg, attrs_) \
 	[ATTRIBUTE_ ## name] = { fg, bg, attrs_ },
@@ -350,6 +350,17 @@ static struct attrs g_attrs[ATTRIBUTE_COUNT] =
 
 #undef ATTRIBUTE_TABLE
 
+static void
+app_init_line_item_colors (void)
+{
+	size_t colors_len = 0;
+	int *colors = filter_color_cube_for_acceptable_nick_colors (&colors_len);
+	hard_assert (g_attrs_len + colors_len <= N_ELEMENTS (g_attrs));
+
+	for (size_t i = 0; i < colors_len; i++)
+		g_attrs[g_attrs_len++] = (struct attrs) { colors[i], -1, 0 };
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 enum { UNREAD_MARKER_HEIGHT = 1 };
@@ -2176,19 +2187,17 @@ app_line_item_color_rgb (int color, int *r, int *g, int *b)
 static int
 app_line_item_color (int16_t color)
 {
-	// These are the closest 256-colour palette matches for the base 16,
-	// using the same RGB estimates as xC and XUI.
 	if (color < 0 || color >= 256)
 		return -1;
 
 	int r = 0, g = 0, b = 0;
 	app_line_item_color_rgb (color, &r, &g, &b);
+
 	int best = 0, best_distance = INT_MAX;
-	for (int i = 0; i < 16; i++)
+	for (size_t i = ATTRIBUTE_IRC_0; i < g_attrs_len; i++)
 	{
 		int rr = 0, gg = 0, bb = 0;
-		app_line_item_color_rgb (g_attrs[ATTRIBUTE_IRC_0 + i].fg,
-			&rr, &gg, &bb);
+		app_line_item_color_rgb (g_attrs[i].fg, &rr, &gg, &bb);
 		int distance =
 			(r - rr) * (r - rr) +
 			(g - gg) * (g - gg) +
@@ -2227,20 +2236,20 @@ app_line_item_attrs (chtype attrs, bool leaked,
 		bg = tmp;
 	}
 
-	// XUI attributes use a small, preallocated colour-pair table.
-	// Preserve its common 16-colour palette, approximating extended colours,
-	// and preferring the foreground when both colours are set.
+	// XUI attributes use a preallocated colour-pair table.  Quantize colours
+	// to the IRC base palette plus xC's acceptable nickname colours,
+	// preferring the foreground when both colours are set.
 	fg = app_line_item_color (fg);
 	bg = app_line_item_color (bg);
 	if (fg >= 0 && bg < 0)
 	{
 		attrs &= ~A_COLOR;
-		attrs |= g_attrs[ATTRIBUTE_IRC_0 + fg].attrs & A_COLOR;
+		attrs |= g_attrs[fg].attrs & A_COLOR;
 	}
 	else if (bg >= 0 && fg < 0)
 	{
 		attrs &= ~A_COLOR;
-		attrs |= g_attrs[ATTRIBUTE_IRC_0 + bg].attrs & A_COLOR;
+		attrs |= g_attrs[bg].attrs & A_COLOR;
 		attrs ^= A_REVERSE;
 	}
 	else if (item->style & BUFFER_LINE_ITEM_INVERSE)
@@ -3851,9 +3860,10 @@ main (int argc, char *argv[])
 
 	xui_preinit ();
 	app_init_bindings ();
+	app_init_line_item_colors ();
 	g_log_message_real = app_log_handler;
 
-	xui_start (&g.poller, requested_gui, g_attrs, ATTRIBUTE_COUNT);
+	xui_start (&g.poller, requested_gui, g_attrs, g_attrs_len);
 	app_select_backend ();
 	xui_invalidate ();