From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Fri, 22 Apr 2016 07:33:23 +0000 (+0200)
Subject: Fix rounding when sizing 1x1 textures
X-Git-Url: http://winboard.nl/cgi-bin?p=xboard.git;a=commitdiff_plain;h=b782bd1af9ba9d45eb6a3f33f546d441b68479a0

Fix rounding when sizing 1x1 textures

When 1x1 textures were sized to the actual square size, this could lead
to bitmaps that were 1 pixel too small, presumably because of rounding.
We now add 0.99 pixel to the desired size of the texture image before
calculating the scaling factor (in floating arithmetic) that has to be
passed to the cairo scaling routine, and this seems to solve the problem.
---

diff --git a/draw.c b/draw.c
index 1d17314..3b4ddec 100644
--- a/draw.c
+++ b/draw.c
@@ -295,7 +295,7 @@ CreatePNGBoard (char *s, int kind)
 		if(f == 0 || r == 0) f = BOARD_WIDTH, r = BOARD_HEIGHT; // 0x0 means 'fits any', so make it fit
 		textureW[kind] = (w*BOARD_WIDTH)/f; // sync cutting locations with square pattern
 		textureH[kind] = (h*BOARD_HEIGHT)/r;
-		n[kind] = r*squareSize/h; // scale to make it fit exactly vertically
+		n[kind] = (r*squareSize + 0.99)/h;  // scale to make it fit exactly vertically
 		modV[kind] = r; modH[kind] = f;
 	    } else
 	    if((p = strstr(s, "xq")) && (p == s || p[-1] == '/')) { // assume full-board image for Xiangqi