Color palette: Finish implementation

Color palette can now be loaded from a resource containing hexadecimal
RGB values.

layer/color-palette.c

@@ -40,6 +40,40 @@ struct _ColorPalette {
 
 G_DEFINE_TYPE(ColorPalette, color_palette, G_TYPE_OBJECT)
 
+/**
+ * @brief Return the number of non empty lines in array
+ *
+ * This function returns the number of non empty lines in an
+ * array. The scanning is either terminated by the given length
+ * or if a \0 terminator is found.
+ *
+ * @param[in] data Array to count lines in
+ * @param[in] length Length of \p data
+ * @return < 0: Error, >=0: Lines
+ */
+static int count_non_empty_lines_in_array(const char *data, size_t length)
+{
+	unsigned int idx;
+	int non_empty_lines;
+	char last_char = '\n';
+
+	if (!data)
+		return -1;
+
+	/* Count each '\n' as a new line if it is not directly preceded by another '\n' */
+	for (idx = 0; idx < length && data[idx]; idx++) {
+		if (data[idx] == '\n' && last_char != '\n')
+			non_empty_lines++;
+		last_char = data[idx];
+	}
+
+	/* Count the last line in case the data does not end with a '\n' */
+	if (data[idx-1] != '\n')
+		non_empty_lines++;
+
+	return non_empty_lines;
+}
+
 /**
  * @brief color_palette_fill_with_resource
  * @param palette
@@ -49,8 +83,16 @@ G_DEFINE_TYPE(ColorPalette, color_palette, G_TYPE_OBJECT)
 static int color_palette_fill_with_resource(ColorPalette *palette, char *resource_name)
 {
 	GBytes *data;
+	char line[10];
+	int line_idx;
+	unsigned int color_idx;
+	int idx;
 	const char *char_array;
 	gsize byte_count;
+	int lines;
+	GRegex *regex;
+	GMatchInfo *mi;
+	char *match;
 
 	if (!palette || !resource_name)
 		return -1;
@@ -65,9 +107,75 @@ static int color_palette_fill_with_resource(ColorPalette *palette, char *resourc
 	if (!char_array || !byte_count)
 		goto ret_unref;
 
+	/* Get maximum lenght of color palette, assuming all entries are valid */
+	lines = count_non_empty_lines_in_array(char_array, byte_count);
+
+	if (lines <= 0)
+		goto ret_unref;
+
+	palette->color_array = (GdkRGBA *)malloc(sizeof(GdkRGBA) * (unsigned int)lines);
+
+	/* Setup regex for hexadecimal RGB colors like 'A0CB3F' */
+	regex = g_regex_new("^(?<red>[0-9A-Fa-f][0-9A-Fa-f])(?<green>[0-9A-Fa-f][0-9A-Fa-f])(?<blue>[0-9A-Fa-f][0-9A-Fa-f])$", 0, 0, NULL);
 
 
+	/* Reset line */
+	line_idx = 0;
+	line[0] = '\0';
 
+	/* Set color index */
+	color_idx = 0;
+
+	/* interate over lines and match */
+	for (idx = 0 ; idx < byte_count; idx++) {
+		/* Fillup line. */
+		line[line_idx] = char_array[idx];
+
+
+		/* If end of line/string is reached, process */
+		if (line[line_idx] == '\n' || line[line_idx] == '\0') {
+			line[line_idx] = '\0';
+
+			/* Match the line */
+			g_regex_match(regex, line, 0, &mi);
+			if (g_match_info_matches(mi) && color_idx < lines) {
+				match = g_match_info_fetch_named(mi, "red");
+				palette->color_array[color_idx].red = (double)g_ascii_strtoll(match, NULL, 16) / 255.0;
+				g_free(match);
+				match = g_match_info_fetch_named(mi, "green");
+				palette->color_array[color_idx].green = (double)g_ascii_strtoll(match, NULL, 16) / 255.0;
+				g_free(match);
+				match = g_match_info_fetch_named(mi, "blue");
+				palette->color_array[color_idx].blue = (double)g_ascii_strtoll(match, NULL, 16) / 255.0;
+				g_free(match);
+
+				/* Only RGB supported so far. Fix alpha channel to 1.0 */
+				palette->color_array[color_idx].alpha = 1.0;
+
+				color_idx++;
+			}
+
+			g_match_info_free(mi);
+
+			/* End of string */
+			if (char_array[idx] == '\0')
+				break;
+
+			line_idx = 0;
+			continue;
+		}
+
+		/* increment line index. If end is reached write all bytes  to the line end
+		 * line is longer than required for parsing. This ensures, that everything works as expected
+		 */
+		line_idx += (line_idx < sizeof(line)-1 ? 1 : 0);
+	}
+
+	/* Data read; Shrink array in case of invalid lines */
+	palette->color_array = realloc(palette->color_array, (size_t)color_idx * sizeof(GdkRGBA));
+	palette->color_array_length = color_idx;
+
+	g_regex_unref(regex);
 ret_unref:
 	g_bytes_unref(data);