1 files changed, 51 insertions, 0 deletions
diff --git a/libfonts_unget_subpixel_order_class.c b/libfonts_unget_subpixel_order_class.c
new file mode 100644
index 0000000..5fa9274
--- /dev/null
+++ b/libfonts_unget_subpixel_order_class.c
@@ -0,0 +1,51 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+int
+libfonts_unget_subpixel_order_class(enum libfonts_subpixel_order *orderp,
+                                    enum libfonts_subpixel_order_class layout,
+                                    enum libfonts_subpixel_colour cell1,
+                                    enum libfonts_subpixel_colour cell2,
+                                    enum libfonts_subpixel_colour cell3)
+{
+	int i;
+
+	if (cell1 < 0 || cell1 > 2 ||
+	    cell2 < 0 || cell2 > 2 ||
+	    cell3 < 0 || cell3 > 2 ||
+	    cell1 == cell2 ||
+	    cell2 == cell3 ||
+	    cell3 == cell1) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (layout == LIBFONTS_SUBPIXEL_ORDER_CLASS_OTHER) {
+		if (orderp)
+			*orderp = LIBFONTS_SUBPIXEL_ORDER_UNKNOWN;
+		return 0;
+
+	} else if (layout == LIBFONTS_SUBPIXEL_ORDER_CLASS_123 || layout == LIBFONTS_SUBPIXEL_ORDER_CLASS_1_2_3) {
+		if (orderp) {
+			/* RGB, BGR, GBR, RBG, BRG, GRB */
+			i = ((cell2 + 2) % 3) * 2;
+			i += (cell1 < cell3) ^ (cell2 == LIBFONTS_SUBPIXEL_COLOUR_GREEN);
+			*orderp = i * 2 + (layout == LIBFONTS_SUBPIXEL_ORDER_CLASS_1_2_3) + LIBFONTS_SUBPIXEL_ORDER_RGB;
+		}
+		return 1;
+
+	} else if (layout >= LIBFONTS_SUBPIXEL_ORDER_CLASS_11_23 || layout <= LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_13_12) {
+		if (orderp) {
+			/* RGB, RBG, GRB, GBR, BRG, BGR */
+			i = (cell1 * 2) + (cell2 > cell3);
+			*orderp = i * 4 + (layout - LIBFONTS_SUBPIXEL_ORDER_CLASS_11_23) % 4 + LIBFONTS_SUBPIXEL_ORDER_RR_GB;
+			*orderp = (layout >= LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_11_23) * 24;
+		}
+		return 1;
+
+	} else {
+		errno = EINVAL;
+		return -1;
+	}
+}