GRAPHICS: Fix potential rounding errors in the h/v thick line drawing

1 files changed, 4 insertions, 2 deletions

diff --git a/graphics/primitives.cpp b/graphics/primitives.cpp
index a879fc9e45..ee240208ac 100644
--- a/graphics/primitives.cpp
+++ b/graphics/primitives.cpp
@@ -108,11 +108,13 @@ void drawThickLine2(int x1, int y1, int x2, int y2, int thick, int color, void (
 	int dy = abs(y2 - y1);
 
 	if (dx == 0) {
-		Common::Rect r(x1 - thick / 2, MIN(y1, y2), x1 + thick / 2, MAX(y1, y2));
+		int xn = x1 - thick / 2;
+		Common::Rect r(xn, MIN(y1, y2), xn + thick, MAX(y1, y2));
 		drawFilledRect(r, color, plotProc, data);
 		return;
 	} else if (dy == 0) {
-		Common::Rect r(MIN(x1, x2), y1 - thick / 2, MAX(x1, x2), y1 + thick / 2);
+		int yn = y1 - thick / 2;
+		Common::Rect r(MIN(x1, x2), yn, MAX(x1, x2), yn + thick);
 		drawFilledRect(r, color, plotProc, data);
 		return;
 	}