From 0522587bcb08d11beca9b828403d76918995f32a Mon Sep 17 00:00:00 2001
From: Artur Wieczorek <artwik@wp.pl>
Date: Thu, 29 Aug 2019 18:35:14 +0200
Subject: [PATCH] Fix creating a bitmap representing wxMask

When bitmap data are accessed with wxNativePixelData, which is designed
to handle RGB bitmaps, Alpha() function cannot be used because in this
case alpha component index is set to the default value -1 and actually
the blue component of the "preceding" pixel is accessed.

Closes #18478.
---
 src/osx/core/bitmap.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/osx/core/bitmap.cpp b/src/osx/core/bitmap.cpp
index 7ea3fa4626..88e327a64b 100644
--- a/src/osx/core/bitmap.cpp
+++ b/src/osx/core/bitmap.cpp
@@ -1697,10 +1697,8 @@ wxBitmap wxMask::GetBitmap() const
         for (int x = 0; x < m_width; ++x, ++p, ++src)
         {
             const unsigned char byte = *src;
-            p.Alpha() = 0xff;
-            p.Red() = byte;
-            p.Green() = byte;
-            p.Blue() = byte;
+            wxASSERT( byte == 0 || byte == 0xFF );
+            p.Red() = p.Green() = p.Blue() = byte;
         }
         p = rowStart;
         p.OffsetY(data, 1);