From 81ad3366f5d7d585e7d87490bc5b3cda8bfd0c07 Mon Sep 17 00:00:00 2001
From: jean-pierre charras <jp.charras@wanadoo.fr>
Date: Tue, 7 Nov 2017 09:45:03 +0100
Subject: [PATCH] Avoid division by 0 in GAL::GetGridPoint( const VECTOR2D&
 aPoint )

---
 common/gal/graphics_abstraction_layer.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/common/gal/graphics_abstraction_layer.cpp b/common/gal/graphics_abstraction_layer.cpp
index b5d763e040..4ed7b6d392 100644
--- a/common/gal/graphics_abstraction_layer.cpp
+++ b/common/gal/graphics_abstraction_layer.cpp
@@ -394,8 +394,19 @@ void GAL::DrawGrid()
 
 VECTOR2D GAL::GetGridPoint( const VECTOR2D& aPoint ) const
 {
+#if 0
+    // This old code expects a non zero grid size, which can be wrong here.
     return VECTOR2D( KiROUND( ( aPoint.x - gridOffset.x ) / gridSize.x ) * gridSize.x + gridOffset.x,
                      KiROUND( ( aPoint.y - gridOffset.y ) / gridSize.y ) * gridSize.y + gridOffset.y );
+#else
+    // if grid size == 0.0 there is no grid, so use aPoint as grid reference position
+    double cx = gridSize.x > 0.0 ? KiROUND( ( aPoint.x - gridOffset.x ) / gridSize.x ) * gridSize.x + gridOffset.x
+            : aPoint.x;
+    double cy = gridSize.y > 0.0 ? KiROUND( ( aPoint.y - gridOffset.y ) / gridSize.y ) * gridSize.y + gridOffset.y
+            : aPoint.y;
+
+    return VECTOR2D( cx, cy );
+#endif
 }
 
 const int GAL::MIN_DEPTH = -1024;