From eabd333355b05bd0b5c2cdc5d52938bb94e6d4fe Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Wed, 10 Nov 2004 23:30:57 +0000
Subject: [PATCH] fixed creation of the mask in wxImage -> wxBitmap conversion
 when bpp < 32 (patch 1052766)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@30435 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/bitmap.cpp | 39 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/msw/bitmap.cpp b/src/msw/bitmap.cpp
index 16e23a409d..3df871c59f 100644
--- a/src/msw/bitmap.cpp
+++ b/src/msw/bitmap.cpp
@@ -843,9 +843,42 @@ bool wxBitmap::CreateFromImage(const wxImage& image, int depth, WXHDC hdc)
     // finally also set the mask if we have one
     if ( image.HasMask() )
     {
-        SetMask(new wxMask(*this, wxColour(image.GetMaskRed(),
-                                           image.GetMaskGreen(),
-                                           image.GetMaskBlue())));
+        const size_t len  = 2*((w+15)/16);
+        BYTE *src  = image.GetData();
+        BYTE *data = new BYTE[h*len];
+        memset(data, 0, h*len);
+        BYTE r = image.GetMaskRed(),
+             g = image.GetMaskGreen(),
+             b = image.GetMaskBlue();
+        BYTE *dst = data;
+        for ( int y = 0; y < h; y++, dst += len )
+        {
+            BYTE *dstLine = dst;
+            BYTE mask = 0x80;
+            for ( int x = 0; x < w; x++, src += 3 )
+            {
+                if (src[0] != r || src[1] != g || src[2] != b)
+                    *dstLine |= mask;
+
+                if ( (mask >>= 1) == 0 )
+                {
+                    dstLine++;
+                    mask = 0x80;
+                }
+            }
+        }
+
+        hbitmap = ::CreateBitmap(w, h, 1, 1, data);
+        if ( !hbitmap )
+        {
+            wxLogLastError(_T("CreateBitmap(mask)"));
+        }
+        else
+        {
+            SetMask(new wxMask((WXHBITMAP)hbitmap));
+        }
+
+        delete data;
     }
 
     return true;