From 00fdd0019370abcc67cf95e9c604aeda4637ac8b Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sat, 21 Jan 2023 14:00:22 +0100
Subject: Add libfonts_get_subpixel_map
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 Makefile                    |   1 +
 libfonts.h                  |  31 ++++
 libfonts_get_subpixel_map.c | 439 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 471 insertions(+)
 create mode 100644 libfonts_get_subpixel_map.c

diff --git a/Makefile b/Makefile
index 32ad9a5..624232d 100644
--- a/Makefile
+++ b/Makefile
@@ -35,6 +35,7 @@ PUBLIC_OBJ =\
 	libfonts_get_output_dpi.o\
 	libfonts_get_output_rendering_settings.o\
 	libfonts_get_subpixel_expansion.o\
+	libfonts_get_subpixel_map.o\
 	libfonts_get_subpixel_order_class.o\
 	libfonts_parse_alias_line.o\
 	libfonts_parse_dir_line.o\
diff --git a/libfonts.h b/libfonts.h
index 3ecd123..f771ab8 100644
--- a/libfonts.h
+++ b/libfonts.h
@@ -2465,5 +2465,36 @@ int libfonts_unget_subpixel_order_class(enum libfonts_subpixel_order *,
  */
 int libfonts_get_subpixel_expansion(enum libfonts_subpixel_order_class, size_t *restrict, size_t *restrict);
 
+/**
+ * Get the abstract colour layout for a subpixel structure
+ * 
+ * @param  layout   The subpixel layout
+ * @param  rowsize  A value such that `y * rowsize + x` is the position
+ *                  `map` for the vertical position `y` (counted top-down from 0)
+ *                   with the horizontal position `x` (counted left-to-right from 0)
+ * @param  map      Output buffer for the subpixel mapping in the layout: where
+ *                  each cell (there may be multiple) set to the value 0 has the colour
+ *                  output in the second parameter of `libfonts_get_subpixel_order_class`,
+ *                  each cell (there may be multiple) set to the value 1 has the colour
+ *                  output in the third parameter of `libfonts_get_subpixel_order_class`,
+ *                  and each cell (there may be multiple) set to the value 2 has the colour
+ *                  output in the fourth parameter of `libfonts_get_subpixel_order_class`;
+ *                  each cell will be given one of these values. The map's width and height
+ *                  is assumed to be the width and height multipliers, respectively, as
+ *                  output by `libfonts_get_subpixel_expansion`
+ * @param   n0p     Output parameter for the number of cells given the value 0
+ * @param   n1p     Output parameter for the number of cells given the value 1
+ * @param   n2p     Output parameter for the number of cells given the value 2
+ * @return          0 on success, -1 on failure
+ * 
+ * @throws  EINVAL  `layout` is `LIBFONTS_SUBPIXEL_ORDER_CLASS_OTHER`
+ * @throws  EINVAL  `layout` is unrecognised
+ * @throws  EINVAL  `rowsize` is less than the width multiplier output by
+ *                  `libfonts_get_subpixel_expansion` (this is however only
+ *                  checked if it is used)
+ */
+int libfonts_get_subpixel_map(enum libfonts_subpixel_order_class, size_t, uint8_t *restrict,
+                              uint8_t *restrict, uint8_t *restrict, uint8_t *restrict);
+
 
 #endif
diff --git a/libfonts_get_subpixel_map.c b/libfonts_get_subpixel_map.c
new file mode 100644
index 0000000..9581a57
--- /dev/null
+++ b/libfonts_get_subpixel_map.c
@@ -0,0 +1,439 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+
+int
+libfonts_get_subpixel_map(enum libfonts_subpixel_order_class layout, size_t rowsize, uint8_t *restrict map,
+                          uint8_t *restrict n0p, uint8_t *restrict n1p, uint8_t *restrict n2p)
+{
+	size_t n0, n1, n2;
+
+#define SET_1_X_3(R1C1, R1C2, R1C3)\
+	do {\
+		if (map) {\
+			map[0] = (R1C1);\
+			map[1] = (R1C2);\
+			map[2] = (R1C3);\
+		}\
+		n0 = 1;\
+		n1 = 1;\
+		n2 = 1;\
+	} while (0)
+
+#define SET_3_X_1(R1C1, R2C1, R3C1)\
+	do {\
+		if (map) {\
+			if (rowsize < 1)\
+				goto einval;\
+			map[0 * rowsize] = (R1C1);\
+			map[1 * rowsize] = (R2C1);\
+			map[2 * rowsize] = (R3C1);\
+		}\
+		n0 = 1;\
+		n1 = 1;\
+		n2 = 1;\
+	} while (0)
+
+#define SET_2_X_2(R1C1, R1C2, R2C1, R2C2)\
+	do {\
+		if (map) {\
+			if (rowsize < 2)\
+				goto einval;\
+			map[0 * rowsize + 0] = (R1C1);\
+			map[0 * rowsize + 1] = (R1C2);\
+			map[1 * rowsize + 0] = (R2C1);\
+			map[1 * rowsize + 1] = (R2C2);\
+		}\
+		n0 = 2;\
+		n1 = 1;\
+		n2 = 1;\
+	} while (0)
+
+#define SET_3_X_2(R1C1, R1C2, R2C1, R2C2, R3C1, R3C2)\
+	do {\
+		if (map) {\
+			if (rowsize < 2)\
+				goto einval;\
+			map[0 * rowsize + 0] = (R1C1);\
+			map[0 * rowsize + 1] = (R1C2);\
+			map[1 * rowsize + 0] = (R2C1);\
+			map[1 * rowsize + 1] = (R2C2);\
+			map[2 * rowsize + 0] = (R3C1);\
+			map[2 * rowsize + 1] = (R3C2);\
+		}\
+		n0 = 2;\
+		n1 = 2;\
+		n2 = 2;\
+	} while (0)
+
+#define SET_2_X_3(R1C1, R1C2, R1C3, R2C1, R2C2, R2C3)\
+	do {\
+		if (map) {\
+			if (rowsize < 3)\
+				goto einval;\
+			map[0 * rowsize + 0] = (R1C1);\
+			map[0 * rowsize + 1] = (R1C2);\
+			map[0 * rowsize + 2] = (R1C3);\
+			map[1 * rowsize + 0] = (R2C1);\
+			map[1 * rowsize + 1] = (R2C2);\
+			map[1 * rowsize + 2] = (R2C3);\
+		}\
+		n0 = 2;\
+		n1 = 2;\
+		n2 = 2;\
+	} while (0)
+
+	switch (layout) {
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_123:
+		SET_1_X_3(0, 1, 2);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_1_2_3:
+		SET_3_X_1(0,
+		          1,
+		          2);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_11_23:
+		SET_2_X_2(0, 0,
+		          1, 2);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_21_31:
+		SET_2_X_2(1, 0,
+		          2, 0);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_32_11:
+		SET_2_X_2(2, 1,
+		          0, 0);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_13_12:
+		SET_2_X_2(0, 2,
+		          0, 1);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_11_23:
+		SET_3_X_2(0, 0,
+		          1, 2,
+		          1, 2);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_21_31:
+		SET_2_X_3(1, 1, 0,
+		          2, 2, 0);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_32_11:
+		SET_3_X_2(2, 1,
+		          2, 1,
+		          0, 0);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_13_12:
+		SET_2_X_3(0, 2, 2,
+		          0, 1, 1);
+		break;
+
+	case LIBFONTS_SUBPIXEL_ORDER_CLASS_OTHER:
+	default:
+		goto einval;
+	}
+
+	if (n0p)
+		*n0p = n0;
+	if (n1p)
+		*n1p = n1;
+	if (n2p)
+		*n2p = n2;
+
+	return 0;
+
+einval:
+	errno = EINVAL;
+	return -1;
+}
+
+
+#else
+
+
+int
+main(void)
+{
+	uint8_t map[128], ns[3];
+	size_t i, j, rowsize;
+
+#define T(L)\
+	do {\
+		errno = 0;\
+		ASSERT(libfonts_get_subpixel_map(L, 16, NULL, NULL, NULL, NULL) == -1);\
+		ASSERT(errno == EINVAL);\
+		\
+		errno = 0;\
+		ASSERT(libfonts_get_subpixel_map(L, 16, map, NULL, NULL, NULL) == -1);\
+		ASSERT(errno == EINVAL);\
+		\
+		errno = 0;\
+		ASSERT(libfonts_get_subpixel_map(L, 16, map, &ns[0], &ns[1], &ns[2]) == -1);\
+		ASSERT(errno == EINVAL);\
+	} while (0)
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_OTHER);
+	T((enum libfonts_subpixel_order_class)999);
+
+#undef T
+
+#define TEST_1_X_3(R1C1, R1C2, R1C3)\
+	do {\
+		ASSERT(map[0] == (R1C1) - 1);\
+		ASSERT(map[1] == (R1C2) - 1);\
+		ASSERT(map[2] == (R1C3) - 1);\
+		ASSERT(ns[0] == 1);\
+		ASSERT(ns[1] == 1);\
+		ASSERT(ns[2] == 1);\
+	} while (0)
+
+#define TEST_3_X_1(R1C1, R2C1, R3C1)\
+	do {\
+		ASSERT(map[0 * rowsize] == (R1C1) - 1);\
+		ASSERT(map[1 * rowsize] == (R2C1) - 1);\
+		ASSERT(map[2 * rowsize] == (R3C1) - 1);\
+		ASSERT(ns[0] == 1);\
+		ASSERT(ns[1] == 1);\
+		ASSERT(ns[2] == 1);\
+	} while (0)
+
+#define TEST_2_X_2(R1C1, R1C2, R2C1, R2C2)\
+	do {\
+		ASSERT(map[0 * rowsize + 0] == (R1C1) - 1);\
+		ASSERT(map[0 * rowsize + 1] == (R1C2) - 1);\
+		ASSERT(map[1 * rowsize + 0] == (R2C1) - 1);\
+		ASSERT(map[1 * rowsize + 1] == (R2C2) - 1);\
+		ASSERT(ns[0] == 2);\
+		ASSERT(ns[1] == 1);\
+		ASSERT(ns[2] == 1);\
+	} while (0)
+
+#define TEST_3_X_2(R1C1, R1C2, R2C1, R2C2, R3C1, R3C2)\
+	do {\
+		ASSERT(map[0 * rowsize + 0] == (R1C1) - 1);\
+		ASSERT(map[0 * rowsize + 1] == (R1C2) - 1);\
+		ASSERT(map[1 * rowsize + 0] == (R2C1) - 1);\
+		ASSERT(map[1 * rowsize + 1] == (R2C2) - 1);\
+		ASSERT(map[2 * rowsize + 0] == (R3C1) - 1);\
+		ASSERT(map[2 * rowsize + 1] == (R3C2) - 1);\
+		ASSERT(ns[0] == 2);\
+		ASSERT(ns[1] == 2);\
+		ASSERT(ns[2] == 2);\
+	} while (0)
+
+#define TEST_2_X_3(R1C1, R1C2, R1C3, R2C1, R2C2, R2C3)\
+	do {\
+		ASSERT(map[0 * rowsize + 0] == (R1C1) - 1);\
+		ASSERT(map[0 * rowsize + 1] == (R1C2) - 1);\
+		ASSERT(map[0 * rowsize + 2] == (R1C3) - 1);\
+		ASSERT(map[1 * rowsize + 0] == (R2C1) - 1);\
+		ASSERT(map[1 * rowsize + 1] == (R2C2) - 1);\
+		ASSERT(map[1 * rowsize + 2] == (R2C3) - 1);\
+		ASSERT(ns[0] == 2);\
+		ASSERT(ns[1] == 2);\
+		ASSERT(ns[2] == 2);\
+	} while (0)
+
+#define TEST_3_X_2_BALANCED_2_X_2(R1C1, R1C2, R2C1, R2C2)\
+	TEST_3_X_2((R1C1), (R1C2),\
+		   (R1C1) == (R1C2) ? (R2C1) : (R1C1),\
+		   (R1C1) == (R1C2) ? (R2C2) : (R1C2),\
+	           (R2C1), (R2C2))
+
+#define TEST_2_X_3_BALANCED_2_X_2(R1C1, R1C2, R2C1, R2C2)\
+	TEST_2_X_3((R1C1), (R1C1) == (R2C1) ? (R1C2) : (R1C1), (R1C2),\
+	           (R2C1), (R1C1) == (R2C1) ? (R2C2) : (R2C1), (R2C2))
+
+#define CHECK_NS(H, W, N0, N1, N2)\
+	do {\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		for (i = 0; i < (H); i++) {\
+			for (j = 0; j < (W); j++) {\
+				ASSERT(map[i * rowsize + j] <= 2);\
+				ns[map[i * rowsize + j]] += 1;\
+			}\
+		}\
+		ASSERT(ns[0] == N0);\
+		ASSERT(ns[1] == N1);\
+		ASSERT(ns[2] == N2);\
+	} while (0)
+
+#define T_(L, ROWSIZE, H, W, MAP, N0, N1, N2, NSCHECK, MAPTEST)\
+	do {\
+		rowsize = (ROWSIZE);\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, NULL, NULL, NULL));\
+		ASSERT(errno == EDOM);\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, &ns[0], NULL, NULL));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[0] == (N0));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, NULL, &ns[1], NULL));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[1] == (N1));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, &ns[0], &ns[1], NULL));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[0] == (N0));\
+		ASSERT(ns[1] == (N1));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, NULL, NULL, &ns[2]));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[2] == (N2));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, &ns[0], NULL, &ns[2]));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[0] == (N0));\
+		ASSERT(ns[2] == (N2));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, NULL, &ns[1], &ns[2]));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[1] == (N1));\
+		ASSERT(ns[2] == (N2));\
+		NSCHECK;\
+		MAPTEST;\
+		\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, rowsize, MAP, &ns[0], &ns[1], &ns[2]));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[0] == (N0));\
+		ASSERT(ns[1] == (N1));\
+		ASSERT(ns[2] == (N2));\
+		NSCHECK;\
+		MAPTEST;\
+	} while (0)
+
+#define T2_(L, ROWSIZE, H, N0, N1, N2, N0P, N1P, N2P)\
+	do {\
+		errno = EDOM;\
+		ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+		ASSERT(!libfonts_get_subpixel_map(L, ROWSIZE, NULL, N0P, N1P, N2P));\
+		ASSERT(errno == EDOM);\
+		ASSERT(ns[0] == (N0));\
+		ASSERT(ns[1] == (N1));\
+		ASSERT(ns[2] == (N2));\
+		\
+		if (H > 1) {\
+			errno = 0;\
+			ASSERT(libfonts_get_subpixel_map(L, ROWSIZE, map, N0P, N1P, N2P) == -1);\
+			ASSERT(errno == EINVAL);\
+		} else {\
+			errno = EDOM;\
+			ns[0] = 0, ns[1] = 0, ns[2] = 0;\
+			ASSERT(!libfonts_get_subpixel_map(L, ROWSIZE, map, N0P, N1P, N2P));\
+			ASSERT(errno == EDOM);\
+			ASSERT(ns[0] == (N0));\
+			ASSERT(ns[1] == (N1));\
+			ASSERT(ns[2] == (N2));\
+		}\
+	} while (0)
+
+#define T(L, H, W, N0, N1, N2, MAPTEST)\
+	do {\
+		T_(L, W, H, W, map, N0, N1, N2, CHECK_NS(H, W, N0, N1, N2), MAPTEST);\
+		T_(L, W, H, W, NULL, N0, N1, N2,,);\
+		T_(L, W + 1, H, W, map, N0, N1, N2, CHECK_NS(H, W, N0, N1, N2), MAPTEST);\
+		T_(L, W + 1, H, W, NULL, N0, N1, N2,,);\
+		T2_(L, W - 1, H, 0, 0, 0, NULL, NULL, NULL);\
+		T2_(L, W - 1, H, N0, 0, 0, &ns[0], NULL, NULL);\
+		T2_(L, W - 1, H, 0, N1, 0, NULL, &ns[1], NULL);\
+		T2_(L, W - 1, H, N0, N1, 0, &ns[0], &ns[1], NULL);\
+		T2_(L, W - 1, H, 0, 0, N2, NULL, NULL, &ns[2]);\
+		T2_(L, W - 1, H, N0, 0, N2, &ns[0], NULL, &ns[2]);\
+		T2_(L, W - 1, H, 0, N1, N2, NULL, &ns[1], &ns[2]);\
+		T2_(L, W - 1, H, N0, N1, N2, &ns[0], &ns[1], &ns[2]);\
+	} while (0)
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_123,
+	  1, 3, 1, 1, 1,
+	  TEST_1_X_3(1, 2, 3));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_1_2_3,
+	  3, 1, 1, 1, 1,
+	  TEST_3_X_1(1,
+	             2,
+	             3));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_11_23,
+	  2, 2, 2, 1, 1,
+	  TEST_2_X_2(1, 1,
+	             2, 3));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_21_31,
+	  2, 2, 2, 1, 1,
+	  TEST_2_X_2(2, 1,
+	             3, 1));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_32_11,
+	  2, 2, 2, 1, 1,
+	  TEST_2_X_2(3, 2,
+	             1, 1));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_13_12,
+	  2, 2, 2, 1, 1,
+	  TEST_2_X_2(1, 3,
+	             1, 2));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_11_23,
+	  3, 2, 2, 2, 2,
+	  TEST_3_X_2(1, 1,
+	             2, 3,
+	             2, 3));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_21_31,
+	  2, 3, 2, 2, 2,
+	  TEST_2_X_3(2, 2, 1,
+	             3, 3, 1));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_32_11,
+	  3, 2, 2, 2, 2,
+	  TEST_3_X_2_BALANCED_2_X_2(3, 2,
+	                            1, 1));
+
+	T(LIBFONTS_SUBPIXEL_ORDER_CLASS_BALANCED_13_12,
+	  2, 3, 2, 2, 2,
+	  TEST_2_X_3_BALANCED_2_X_2(1, 3,
+	                            1, 2));
+
+	return 0;
+}
+
+
+#endif
-- 
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