From 66efe66f61b76e4eee0cedebb04b1aef3d65e404 Mon Sep 17 00:00:00 2001
From: Dobrica Pavlinusic <dpavlin@rot13.org>
Date: Wed, 26 Sep 2012 18:54:49 +0200
Subject: [PATCH] invertRect should handle negative x or y values

two-column mode combined with showing links in pdf files triggers this bug
---
 blitbuffer.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/blitbuffer.c b/blitbuffer.c
index aef8bab72..0e4d30b69 100644
--- a/blitbuffer.c
+++ b/blitbuffer.c
@@ -394,6 +394,29 @@ static int invertRect(lua_State *L) {
 	uint8_t *dstptr;
 
 	int cy, cx;
+
+	//printf("## invertRect x=%d y=%d w=%d h=%d\n",x,y,w,h);
+
+	if (x < 0) {
+		if ( x + w > 0 ) {
+			w = w + x;
+			x = 0;
+		} else {
+			//printf("## invertRect x out of bound\n");
+			return 0;
+		}
+	}
+
+	if (y < 0) {
+		if ( y + h > 0 ) {
+			h = h + y;
+			y = 0;
+		} else {
+			//printf("## invertRect y out of bound\n");
+			return 0;
+		}
+	}
+
 	if(w <= 0 || h <= 0 || x >= dst->w || y >= dst->h) {
 		return 0;
 	}