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Fix display of bitmaps with alpha in wxStaticBitmap under MSW.

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Avoid double alpha pre-multiplication by converting the bitmap into a non
pre-multiplied format before passing it to STM_SETIMAGE.

Closes #2395.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75735 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2014-01-29 22:25:41 +00:00
parent 0a411fd5da
commit cc4658d1f4
1 changed files with 27 additions and 1 deletions
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28
src/msw/statbmp.cpp
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@ -35,6 +35,7 @@
#endif
#include "wx/msw/private.h"
#include "wx/msw/dib.h"
#include "wx/sysopt.h"
@ -266,6 +267,26 @@ void wxStaticBitmap::SetImageNoCopy( wxGDIImage* image)
#ifdef __WIN32__
HANDLE handle = (HANDLE)m_image->GetHandle();
AutoHBITMAP hbmpRelease;
if ( !m_isIcon )
{
// wxBitmap normally stores alpha in pre-multiplied format but
// apparently STM_SETIMAGE message handler does pre-multiplication
// internally so we need to undo the pre-multiplication here for a
// while (this is similar to what we do in ImageList::Add()).
const wxBitmap& bmp = static_cast<wxBitmap&>(*image);
if ( bmp.HasAlpha() )
{
// For bitmap with alpha channel create temporary DIB with
// not-premultiplied alpha values.
handle = wxDIB(bmp.ConvertToImage(),
wxDIB::PixelFormat_NotPreMultiplied).Detach();
// Ensure that this temporary HBITMAP will be destroyed.
hbmpRelease.Init((HBITMAP)handle);
}
}
LONG style = ::GetWindowLong( (HWND)GetHWND(), GWL_STYLE ) ;
::SetWindowLong( (HWND)GetHWND(), GWL_STYLE, ( style & ~( SS_BITMAP|SS_ICON ) ) |
( m_isIcon ? SS_ICON : SS_BITMAP ) );
@ -278,7 +299,12 @@ void wxStaticBitmap::SetImageNoCopy( wxGDIImage* image)
// the static control made a copy and we are responsible for deleting it
DeleteObject((HGDIOBJ) oldHandle);
}
m_currentHandle = (WXHANDLE)handle;
// Save bitmap handle only if it's not a temporary one, otherwise it's
// going to be destroyed right now anyhow.
if ( !hbmpRelease )
m_currentHandle = (WXHANDLE)handle;
#endif // Win32
if ( ImageIsOk() )