From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 16 Nov 2024 23:33:30 +0000 (+0000)
Subject: Some infrastructure towards edge hints
X-Git-Tag: bedstead-3.246~26
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=1ad04e13fa255e46395c022fdc8697fbc4c91851;p=bedstead.git

Some infrastructure towards edge hints

There are places to record them now, but they're ignored by
select_hints() and emit_hints().
---

diff --git a/bedstead.c b/bedstead.c
index e120c75..6af8523 100644
--- a/bedstead.c
+++ b/bedstead.c
@@ -3808,51 +3808,79 @@ emit_path(void)
 	printf(" endchar");
 }
 
+/* An "A" edge is top or left, a "Z" edge is bottom or right. */
+enum hint_type {
+	hint_none, hint_stem, hint_aedge, hint_zedge
+};
+
 static void
-select_hints(int nstems, int stems[nstems])
+select_hints(int nstems, int stems[nstems],
+	     int aedges[nstems], int zedges[nstems],
+	     enum hint_type hints[nstems])
 {
+	int most = 0;
 
+	/* Find longest stems. */
 	for (int i = 0; i < nstems; i++) {
-		if (stems[i] > 0) {
-			stems[i] = 1;
-			if (i + 1 < nstems) stems[i + 1] = 0;
+		hints[i] = hint_none;
+		if (stems[i] > most) most = stems[i];
+	}
+	for (;most > 0; most--) {
+		/* Prefer long stems. */
+		for (int i = 0; i < nstems; i++) {
+			if (stems[i] == most) {
+				hints[i] = hint_stem;
+				stems[i] = 0;
+				/* Disallow overlapping stems. */
+				if (i >= 1) stems[i-1] = 0;
+				if (i < nstems - 1) stems [i+1] = 0;
+			}
 		}
 	}
 }
 
 static void
-emit_hints(int vstems[XSIZE], int hstems[YSIZE])
+emit_hints(int vstems[XSIZE], int ledges[XSIZE], int redges[XSIZE],
+	   int hstems[YSIZE], int tedges[YSIZE], int bedges[YSIZE])
 {
 	int i, start, size, cur;
+	enum hint_type vhints[XSIZE], hhints[YSIZE];
 	bool printed;
 
-	select_hints(YSIZE, hstems);
+	select_hints(YSIZE, hstems, tedges, bedges, hhints);
 	cur = DESCENT * YPIX; printed = false;
-	size = YPIX_S;
 	for (i = YSIZE - 1; i >= 0; i--) {
-		if (hstems[i] > 0) {
+		switch (hhints[i]) {
+		case hint_stem:
 			start = (YSIZE - i - 1) * YPIX_S;
-			printf(" %g %g",
-			       (double)((start - cur) / YSCALE),
-			       (double)(size / YSCALE));
-			cur = start + size;
-			printed = true;
+			size = YPIX_S;
+			break;
+		default: continue;
 		}
+		printf(" %g %g",
+		       (double)((start - cur) / YSCALE),
+		       (double)(size / YSCALE));
+		cur = start + size;
+		printed = true;
 	}
 	if (printed) printf(" hstem");
 
-	select_hints(XSIZE, vstems);
+	select_hints(XSIZE, vstems, ledges, redges, vhints);
 	cur = 0; printed = false;
 	size = XPIX_S + weight->weight;
 	for (i = 0; i < XSIZE; i++) {
-		if (vstems[i] > 0) {
+		switch (vhints[i]) {
+		case hint_stem:
 			start = i * XPIX_S - weight->weight;
-			printf(" %g %g",
-			       (double)((start - cur) / XSCALE),
-			       (double)(size / XSCALE));
-			cur = start + size;
-			printed = true;
+			size = XPIX_S + weight->weight;
+			break;
+		default: continue;
 		}
+		printf(" %g %g",
+		       (double)((start - cur) / XSCALE),
+		       (double)(size / XSCALE));
+		cur = start + size;
+		printed = true;
 	}
 	if (printed) printf(" vstem");
 }
@@ -3994,7 +4022,8 @@ static void
 dochar(struct glyph *g)
 {
 	int x, y;
-	int vstems[XSIZE], hstems[YSIZE];
+	int vstems[XSIZE], ledges[XSIZE], redges[XSIZE];
+	int hstems[YSIZE], tedges[YSIZE], bedges[YSIZE];
 
 #define GETPIX(x,y) (getpix(g->data, (x), (y), g->flags))
 #define L GETPIX(x-1, y)
@@ -4029,11 +4058,15 @@ dochar(struct glyph *g)
 				blackpixel(x, YSIZE - y - 1, bl, br, tr, tl);
 				if (!L && !R && (U || D))
 					vstems[x]++;
-				if (!U && !D && (L || R))
-					hstems[y]++;
-				if (UL + U + UR + L + R + DL + D + DR == 0) {
-					vstems[x]++;
+				else if (!U && !D && (L || R))
 					hstems[y]++;
+				else if (UL + U + UR + L + R + DL + D + DR == 0)
+					vstems[x]++, hstems[y]++;
+				else { /* Not a stem.  Maybe an edge? */
+					if (UL + U + UR == 0) tedges[y]++;
+					if (DL + D + DR == 0) bedges[y]++;
+					if (UL + L + DL == 0) ledges[x]++;
+					if (UR + R + DR == 0) redges[x]++;
 				}
 			} else {
 				bool tl, tr, bl, br;
@@ -4052,7 +4085,7 @@ dochar(struct glyph *g)
 	clean_path();
 	adjust_weight();
 	record_lsb(g);
-	emit_hints(vstems, hstems);
+	emit_hints(vstems, ledges, redges, hstems, tedges, bedges);
 	emit_path();
 }