Fix missing diagram in 1522*.pdf

Since the commit to replace abs/min/max/clamp with inline versions,
"1522 - diagramm missing above 88 pc zoom.pdf" has been missing a
diagram. This is because the diagram contains sections like:

 -2147483648 -2147483648 m
 -2147483648 2147483647 l
  2147483647 2147483647 l
  2147483647 -2147483648 l

These extreme values, when transformed would give floating point values
that when naively cast down to int, flip sign (e.g. extreme positive
when cast to int becomes extreme negative).

I had been relying on the cast down giving sane results to enable me to
use fz_clampi. Revert to using fz_clamp and all is fine.

1 files changed, 8 insertions, 4 deletions

diff --git a/draw/draw_edge.c b/draw/draw_edge.c
index 48496acd..ff5dcdfc 100644
--- a/draw/draw_edge.c
+++ b/draw/draw_edge.c
@@ -356,10 +356,14 @@ fz_insert_gel(fz_gel *gel, float fx0, float fy0, float fx1, float fy1)
 	fy0 = floorf(fy0 * fz_aa_vscale);
 	fy1 = floorf(fy1 * fz_aa_vscale);
 
-	x0 = fz_clampi(fx0, BBOX_MIN * fz_aa_hscale, BBOX_MAX * fz_aa_hscale);
-	y0 = fz_clampi(fy0, BBOX_MIN * fz_aa_vscale, BBOX_MAX * fz_aa_vscale);
-	x1 = fz_clampi(fx1, BBOX_MIN * fz_aa_hscale, BBOX_MAX * fz_aa_hscale);
-	y1 = fz_clampi(fy1, BBOX_MIN * fz_aa_vscale, BBOX_MAX * fz_aa_vscale);
+	/* Call fz_clamp so that clamping is done in the float domain, THEN
+	 * cast down to an int. Calling fz_clampi causes problems due to the
+	 * implicit cast down from float to int of the first argument
+	 * over/underflowing and flipping sign at extreme values. */
+	x0 = (int)fz_clamp(fx0, BBOX_MIN * fz_aa_hscale, BBOX_MAX * fz_aa_hscale);
+	y0 = (int)fz_clamp(fy0, BBOX_MIN * fz_aa_vscale, BBOX_MAX * fz_aa_vscale);
+	x1 = (int)fz_clamp(fx1, BBOX_MIN * fz_aa_hscale, BBOX_MAX * fz_aa_hscale);
+	y1 = (int)fz_clamp(fy1, BBOX_MIN * fz_aa_vscale, BBOX_MAX * fz_aa_vscale);
 
 	d = clip_lerp_y(gel->clip.y0, 0, x0, y0, x1, y1, &v);
 	if (d == OUTSIDE) return;