allow overriding automatic alpha detection during icon->bitmap conversions (slightly modified patch 1738168)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47629 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/bitmap.h

@@ -30,6 +30,15 @@ class WXDLLIMPEXP_FWD_CORE wxMask;
 class WXDLLIMPEXP_FWD_CORE wxPalette;
 class WXDLLIMPEXP_FWD_CORE wxPixelDataBase;
 
+// What kind of transparency should a bitmap copied from an icon or cursor
+// have?
+enum wxBitmapTransparency
+{
+  wxBitmapTransparency_Auto,    // default: copy alpha if the source has it
+  wxBitmapTransparency_None,    // never create alpha
+  wxBitmapTransparency_Always   // always use alpha
+};
+
 // ----------------------------------------------------------------------------
 // wxBitmap: a mono or colour bitmap
 // ----------------------------------------------------------------------------
@@ -80,7 +89,11 @@ public:
 
     // we must have this, otherwise icons are silently copied into bitmaps using
     // the copy ctor but the resulting bitmap is invalid!
-    wxBitmap(const wxIcon& icon) { CopyFromIcon(icon); }
+    wxBitmap(const wxIcon& icon,
+             wxBitmapTransparency transp = wxBitmapTransparency_Auto)
+    {
+        CopyFromIcon(icon, transp);
+    }
 
     wxBitmap& operator=(const wxIcon& icon)
     {
@@ -106,10 +119,12 @@ public:
     wxBitmap GetSubBitmap( const wxRect& rect ) const;
 
     // copies the contents and mask of the given (colour) icon to the bitmap
-    bool CopyFromIcon(const wxIcon& icon);
+    bool CopyFromIcon(const wxIcon& icon,
+                      wxBitmapTransparency transp = wxBitmapTransparency_Auto);
 
     // copies the contents and mask of the given cursor to the bitmap
-    bool CopyFromCursor(const wxCursor& cursor);
+    bool CopyFromCursor(const wxCursor& cursor,
+                        wxBitmapTransparency transp = wxBitmapTransparency_Auto);
 
 #if wxUSE_WXDIB
     // copies from a device independent bitmap
@@ -175,7 +190,9 @@ protected:
 
 private:
     // common part of CopyFromIcon/CopyFromCursor for Win32
-    bool CopyFromIconOrCursor(const wxGDIImage& icon);
+    bool
+    CopyFromIconOrCursor(const wxGDIImage& icon,
+                         wxBitmapTransparency transp = wxBitmapTransparency_Auto);
 
 
     DECLARE_DYNAMIC_CLASS(wxBitmap)

src/msw/bitmap.cpp

@@ -289,9 +289,8 @@ wxObjectRefData *wxBitmap::CloneRefData(const wxObjectRefData *dataOrig) const
     return m_refData;
 }
 
-#ifdef __WIN32__
+bool wxBitmap::CopyFromIconOrCursor(const wxGDIImage& icon,
-
+                                    wxBitmapTransparency transp)
-bool wxBitmap::CopyFromIconOrCursor(const wxGDIImage& icon)
 {
 #if !defined(__WXMICROWIN__) && !defined(__WXWINCE__)
     // it may be either HICON or HCURSOR
@@ -317,31 +316,51 @@ bool wxBitmap::CopyFromIconOrCursor(const wxGDIImage& icon)
 
     refData->m_hBitmap = (WXHBITMAP)iconInfo.hbmColor;
 
-#if wxUSE_WXDIB
+    switch ( transp )
-    // If the icon is 32 bits per pixel then it may have alpha channel data,
-    // although there are some icons that are 32 bpp but have no alpha... So
-    // convert to a DIB and manually check the 4th byte for each pixel.
-    BITMAP bm;
-    if ( ::GetObject(iconInfo.hbmColor, sizeof(BITMAP), (LPVOID)&bm)
-         && bm.bmBitsPixel == 32)
     {
-        wxDIB dib(iconInfo.hbmColor);
+        default:
-        if (dib.IsOk())
+            wxFAIL_MSG( _T("unknown wxBitmapTransparency value") );
-        {
+
-            unsigned char* pixels = dib.GetData();
+        case wxBitmapTransparency_None:
-            for (int idx=0; idx<w*h*4; idx+=4)
+            // nothing to do, refData->m_hasAlpha is false by default
+            break;
+
+        case wxBitmapTransparency_Auto:
+#if wxUSE_WXDIB
+            // If the icon is 32 bits per pixel then it may have alpha channel
+            // data, although there are some icons that are 32 bpp but have no
+            // alpha... So convert to a DIB and manually check the 4th byte for
+            // each pixel.
             {
-                if (pixels[idx+3] != 0)
+                BITMAP bm;
+                if ( ::GetObject(iconInfo.hbmColor, sizeof(bm), &bm) &&
+                        (bm.bmBitsPixel == 32) )
                 {
-                    // If there is an alpha byte that is non-zero then set the
+                    wxDIB dib(iconInfo.hbmColor);
-                    // alpha flag and bail out of the loop.
+                    if (dib.IsOk())
-                    refData->m_hasAlpha = true;
+                    {
-                    break;
+                        const unsigned char* pixels = dib.GetData();
+                        for (int idx = 0; idx < w*h*4; idx+=4)
+                        {
+                            if (pixels[idx+3] != 0)
+                            {
+                                // If there is an alpha byte that is non-zero
+                                // then set the alpha flag and stop checking
+                                refData->m_hasAlpha = true;
+                                break;
+                            }
+                        }
+                    }
                 }
             }
-        }
+            break;
+#endif // wxUSE_WXDIB
+
+        case wxBitmapTransparency_Always:
+            refData->m_hasAlpha = true;
+            break;
     }
-#endif
+
     if ( !refData->m_hasAlpha )
     {
         // the mask returned by GetIconInfo() is inverted compared to the usual
@@ -353,32 +372,30 @@ bool wxBitmap::CopyFromIconOrCursor(const wxGDIImage& icon)
     ::DeleteObject(iconInfo.hbmMask);
 
     return true;
-#else
+#else // __WXMICROWIN__ || __WXWINCE__
     wxUnusedVar(icon);
     return false;
-#endif
+#endif // !__WXWINCE__/__WXWINCE__
 }
 
-#endif // Win32
+bool wxBitmap::CopyFromCursor(const wxCursor& cursor, wxBitmapTransparency transp)
-
-bool wxBitmap::CopyFromCursor(const wxCursor& cursor)
 {
     UnRef();
 
     if ( !cursor.Ok() )
         return false;
 
-    return CopyFromIconOrCursor(cursor);
+    return CopyFromIconOrCursor(cursor, transp);
 }
 
-bool wxBitmap::CopyFromIcon(const wxIcon& icon)
+bool wxBitmap::CopyFromIcon(const wxIcon& icon, wxBitmapTransparency transp)
 {
     UnRef();
 
     if ( !icon.Ok() )
         return false;
 
-    return CopyFromIconOrCursor(icon);
+    return CopyFromIconOrCursor(icon, transp);
 }
 
 #ifndef NEVER_USE_DIB