From cfded96627cd5906c55b8d47112b8e00bd0c8c44 Mon Sep 17 00:00:00 2001
From: Stefan Csomor <csomor@advancedconcepts.ch>
Date: Sun, 17 Mar 2019 12:19:53 +0100
Subject: [PATCH] fixing truncation error  in GetSubBitmap

fixes #18362
---
 src/osx/core/bitmap.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/osx/core/bitmap.cpp b/src/osx/core/bitmap.cpp
index fcfb40816b..004b67c347 100644
--- a/src/osx/core/bitmap.cpp
+++ b/src/osx/core/bitmap.cpp
@@ -1026,8 +1026,8 @@ wxBitmap wxBitmap::GetSubBitmap(const wxRect &rect) const
         {
             int sourcelinesize = GetBitmapData()->GetBytesPerRow() ;
             int destlinesize = ret.GetBitmapData()->GetBytesPerRow() ;
-            unsigned char *source = sourcedata + int(rect.x * scale * 4 + rect.y *scale * sourcelinesize) ;
-            unsigned char *dest = destdata ;
+            unsigned char* source = sourcedata + size_t(rect.x * scale) * 4 + size_t(rect.y * scale) * sourcelinesize;
+            unsigned char* dest = destdata;
 
             for (int yy = 0; yy < destheight; ++yy, source += sourcelinesize , dest += destlinesize)
             {