1 files changed, 176 insertions, 0 deletions
diff --git a/render/scanconv.c b/render/scanconv.c
new file mode 100644
index 00000000..b2d32363
--- /dev/null
+++ b/render/scanconv.c
@@ -0,0 +1,176 @@
+#include <fitz.h>
+
+static inline void
+addspan(short *list, int x0, int x1, int xofs, int hs)
+{
+	int x0pix, x0sub;
+	int x1pix, x1sub;
+
+	if (x0 == x1)
+		return;
+
+	/* x between 0 and width of bbox */
+	x0 -= xofs;
+	x1 -= xofs;
+
+	x0pix = x0 / hs;
+	x0sub = x0 % hs;
+	x1pix = x1 / hs;
+	x1sub = x1 % hs;
+
+	if (x0pix == x1pix)
+	{
+		list[x0pix] += x1sub - x0sub;
+		list[x0pix+1] += x0sub - x1sub;
+	}
+
+	else
+	{
+		list[x0pix] += hs - x0sub;
+		list[x0pix+1] += x0sub;
+		list[x1pix] += x1sub - hs;
+		list[x1pix+1] += -x1sub;
+	}
+}
+
+static inline void
+nonzerowinding(fz_ael *ael, short *list, int xofs, int hs)
+{
+	int winding = 0;
+	int x = 0;
+	int i;
+	for (i = 0; i < ael->len; i++)
+	{
+		if (!winding && (winding + ael->edges[i]->ydir))
+			x = ael->edges[i]->x;
+		if (winding && !(winding + ael->edges[i]->ydir))
+			addspan(list, x, ael->edges[i]->x, xofs, hs);
+		winding += ael->edges[i]->ydir;
+	}
+}
+
+static inline void
+evenodd(fz_ael *ael, short *list, int xofs, int hs)
+{
+	int even = 0;
+	int x = 0;
+	int i;
+	for (i = 0; i < ael->len; i++)
+	{
+		if (!even)
+			x = ael->edges[i]->x;
+		else
+			addspan(list, x, ael->edges[i]->x, xofs, hs);
+		even = !even;
+	}
+}
+
+/* XXX */
+
+unsigned char pixmap[1000 * 1000];
+
+void
+fz_emitdeltas(short *list, int y, int x, int n)
+{
+	short a = 0;
+	short d = 0;
+	while (n--) {
+		d = *list++;
+		a += d;
+		pixmap[y * 1000 + x] = 0xff - a;
+		x ++;
+	}
+}
+
+void
+savestuff(void)
+{
+	FILE *f = fopen("out.pgm", "w");
+	fprintf(f, "P5\n1000 1000\n255\n");
+	fwrite(pixmap, 1, 1000 * 1000, f);
+	fclose(f);
+}
+
+/* XXX */
+
+void
+fz_emitdeltas0(short *list, int y, int xofs, int n)
+{
+	int d = 0;
+	while (n--)
+		d += *list++;
+}
+
+fz_error *
+fz_scanconvert(fz_gel *gel, fz_ael *ael, int eofill)
+{
+	fz_error *error;
+	short *deltas;
+	int y, e;
+	int yd, yc;
+
+	int xmin = fz_idiv(gel->xmin, gel->hs);
+	int xmax = fz_idiv(gel->xmax, gel->hs) + 1;
+	int ymin = fz_idiv(gel->ymin, gel->vs);
+	int ymax = fz_idiv(gel->ymax, gel->vs) + 1;
+
+	int xofs = xmin * gel->hs;
+	int hs = gel->hs;
+	int vs = gel->vs;
+
+	if (gel->len == 0)
+		return nil;
+
+memset(pixmap, 0xff, sizeof pixmap);
+
+printf("bbox [%d %d %d %d] samp %d/%d edges %d\n",
+	xmin, ymin, xmax, ymax, hs, vs, gel->len);
+
+	deltas = fz_malloc(sizeof(short) * (xmax - xmin));
+	if (!deltas)
+		return fz_outofmem;
+	memset(deltas, 0, sizeof(short) * (xmax - xmin));
+
+	e = 0;
+	y = gel->edges[0].y;
+	yc = fz_idiv(y, vs);
+	yd = yc;
+
+	while (ael->len > 0 || e < gel->len)
+	{
+		yc = fz_idiv(y, vs);
+		if (yc != yd) {
+			fz_emitdeltas(deltas, yd, xmin, xmax - xmin);
+			memset(deltas, 0, sizeof(short) * (xmax - xmin));
+		}
+		yd = yc;
+
+		error = fz_insertael(ael, gel, y, &e);
+		if (error) {
+			fz_free(deltas);
+			return error;
+		}
+
+// { int i; for (i = 0; i < ael->len; i++)
+// pixmap[yd * 1000 + (ael->edges[i]->x / hs)] = 0; }
+
+		if (eofill)
+			evenodd(ael, deltas, xofs, hs);
+		else
+			nonzerowinding(ael, deltas, xofs, hs);
+
+		fz_advanceael(ael);
+
+		if (ael->len > 0)
+			y ++;
+		else if (e < gel->len)
+			y = gel->edges[e].y;
+	}
+
+	fz_emitdeltas(deltas, yd, xmin, xmax - xmin);
+
+	savestuff();
+
+	return nil;
+}
+