X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=src%2Fdraw%2Fao_line.c;fp=src%2Fdraw%2Fao_line.c;h=b427892b01bc17ebd9faaa12c26fd8c9f941d4e2;hb=c5734e9e38bc583aff305e3c534cfb8b9088bc71;hp=0000000000000000000000000000000000000000;hpb=83cfc271e37f568cb1d821cf6a96750f3ca3854c;p=fw%2Faltos

diff --git a/src/draw/ao_line.c b/src/draw/ao_line.c
new file mode 100644
index 00000000..b427892b
--- /dev/null
+++ b/src/draw/ao_line.c
@@ -0,0 +1,164 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao.h"
+#include "ao_draw.h"
+#include "ao_draw_int.h"
+
+#define ao_mask(x,w)	(ao_right(AO_ALLONES,(x) & AO_MASK) & \
+			 ao_left(AO_ALLONES,(FB_UNIT - ((x)+(w))) & AO_MASK))
+
+
+/* out of clip region codes */
+#define OUT_LEFT 0x08
+#define OUT_RIGHT 0x04
+#define OUT_ABOVE 0x02
+#define OUT_BELOW 0x01
+
+/* major axis for bresenham's line */
+#define X_AXIS	0
+#define Y_AXIS	1
+
+static void
+ao_bres(const struct ao_bitmap	*dst_bitmap,
+	int16_t		signdx,
+	int16_t		signdy,
+	int16_t		axis,
+	int16_t		x1,
+	int16_t		y1,
+	int16_t		e,
+	int16_t		e1,
+	int16_t		e3,
+	int16_t		len,
+	uint32_t	and,
+	uint32_t	xor)
+{
+	int16_t		stride = dst_bitmap->stride;
+	uint32_t	*dst = dst_bitmap->base;
+	uint32_t	mask0, mask;
+
+	mask0 = 1;
+	if (signdx < 0)
+		mask0 = ao_right(1, AO_UNIT - 1);
+
+	if (signdy < 0)
+		stride = -stride;
+
+	dst = dst + y1 * stride + (x1 >> AO_SHIFT);
+	mask = ao_right(1, x1 & AO_MASK);
+
+	while (len--) {
+		/* clip each point */
+
+		if (0 <= x1 && x1 < dst_bitmap->width &&
+		    0 <= y1 && y1 < dst_bitmap->height)
+			*dst = ao_do_mask_rrop(*dst, and, xor, mask);
+
+		if (axis == X_AXIS) {
+			if (signdx < 0)
+				mask = ao_left(mask, 1);
+			else
+				mask = ao_right(mask, 1);
+			if (!mask) {
+				dst += signdx;
+				mask = mask0;
+			}
+			x1 += signdx;
+			e += e1;
+			if (e >= 0) {
+				dst += stride;
+				e += e3;
+				y1 += signdy;
+			}
+		} else {
+			dst += stride;
+			e += e1;
+			y1 += signdy;
+			if (e >= 0) {
+				if (signdx < 0)
+					mask = ao_left(mask, 1);
+				else
+					mask = ao_right(mask, 1);
+				if (!mask) {
+					dst += signdx;
+					mask = mask0;
+				}
+				e += e3;
+				x1 += signdx;
+			}
+		}
+	}
+}
+
+
+#define bound(val,max) do {			\
+		if (val < 0) {			\
+			val = 0;		\
+		}				\
+		if (val > max) {		\
+			val = max;		\
+		}				\
+	} while (0)
+
+void
+ao_line(const struct ao_bitmap	*dst,
+	int16_t			x1,
+	int16_t			y1,
+	int16_t			x2,
+	int16_t			y2,
+	uint32_t		fill,
+	uint8_t			rop)
+{
+	int16_t	adx, ady;
+	int16_t	e, e1, e2, e3;
+	int16_t	signdx = 1, signdy = 1;
+	int16_t axis;
+	int16_t len;
+
+	if ((adx = x2 - x1) < 0) {
+		adx = -adx;
+		signdx = -1;
+	}
+	if ((ady = y2 - y1) < 0) {
+		ady = -ady;
+		signdy = -1;
+	}
+
+	if (adx > ady) {
+		axis = X_AXIS;
+		e1 = ady << 1;
+		e2 = e1 - (adx << 1);
+		e = e1 - adx;
+		len = adx;
+	} else {
+		axis = Y_AXIS;
+		e1 = adx << 1;
+		e2 = e1 - (ady << 1);
+		e = e1 - ady;
+		len = ady;
+	}
+
+	e3 = e2 - e1;
+	e = e - e1;
+
+	ao_bres(dst,
+		signdx,
+		signdy,
+		axis,
+		x1,
+		y1,
+		e, e1, e3, len,
+		ao_and(rop, fill),
+		ao_xor(rop, fill));
+}