From add40a2de207cadf4d851aacff7ca73745b7bbdb Mon Sep 17 00:00:00 2001
From: Jonathan G Rennison <j.g.rennison@gmail.com>
Date: Sun, 17 Aug 2025 15:26:23 +0100
Subject: [PATCH] Fix #10222: Off by one drawing even-width horizontal/vertical
 lines

---
 src/blitter/common.hpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/blitter/common.hpp b/src/blitter/common.hpp
index 0347aa8002..f1ea61c0ec 100644
--- a/src/blitter/common.hpp
+++ b/src/blitter/common.hpp
@@ -78,11 +78,11 @@ void Blitter::DrawLineGeneric(int x1, int y1, int x2, int y2, int screen_width,
 		int frac_low  = dy - frac_diff / 2;
 		int frac_high = dy + frac_diff / 2;
 
-		while (frac_low < -(dx / 2)) {
+		while (frac_low < -dx) {
 			frac_low += dx;
 			y_low -= stepy;
 		}
-		while (frac_high >= dx / 2) {
+		while (frac_high >= 0) {
 			frac_high -= dx;
 			y_high += stepy;
 		}
@@ -141,11 +141,11 @@ void Blitter::DrawLineGeneric(int x1, int y1, int x2, int y2, int screen_width,
 		int frac_low  = dx - frac_diff / 2;
 		int frac_high = dx + frac_diff / 2;
 
-		while (frac_low < -(dy / 2)) {
+		while (frac_low < -dy) {
 			frac_low += dy;
 			x_low -= stepx;
 		}
-		while (frac_high >= dy / 2) {
+		while (frac_high >= 0) {
 			frac_high -= dy;
 			x_high += stepx;
 		}