// Name: wx/animdecod.h
// Purpose: wxAnimationDecoder
// Author: Francesco Montorsi
-// CVS-ID: $Id$
// Copyright: (c) 2006 Francesco Montorsi
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
#include "wx/colour.h"
#include "wx/gdicmn.h"
+#include "wx/log.h"
+#include "wx/stream.h"
-class WXDLLIMPEXP_BASE wxInputStream;
-class WXDLLIMPEXP_CORE wxImage;
+class WXDLLIMPEXP_FWD_CORE wxImage;
/*
wxAnimationDecoders always load an input stream using some optimized format
to store it which is format-depedent. This allows to store a (possibly big)
animation using a format which is a good compromise between required memory
- and time required to blit in on the screen.
+ and time required to blit it on the screen.
- 2) wxAnimationDecoders contain the animation data in some internal var.
+ 2) wxAnimationDecoders contain the animation data in some internal variable.
That's why they derive from wxObjectRefData: they are data which can be shared.
3) wxAnimationDecoders can be used by a wxImageHandler to retrieve a frame
in wxImage format; the viceversa cannot be done.
- 4) wxAnimationDecoders are decoders only, thus do not support save features.
+ 4) wxAnimationDecoders are decoders only, thus they do not support save features.
5) wxAnimationDecoders are directly used by wxAnimation (generic implementation)
as wxObjectRefData while they need to be 'wrapped' by a wxImageHandler for
// Do not dispose. The graphic is to be left in place.
wxANIM_DONOTREMOVE = 0,
- // Restore to background color. The area used by the graphic must be
+ // Restore to background color. The area used by the graphic must be
// restored to the background color.
wxANIM_TOBACKGROUND = 1,
- // Restore to previous. The decoder is required to restore the area
+ // Restore to previous. The decoder is required to restore the area
// overwritten by the graphic with what was there prior to rendering the graphic.
wxANIM_TOPREVIOUS = 2
};
// wxAnimationDecoder class
// --------------------------------------------------------------------------
-class WXDLLEXPORT wxAnimationDecoder : public wxObjectRefData
+class WXDLLIMPEXP_CORE wxAnimationDecoder : public wxObjectRefData
{
public:
wxAnimationDecoder()
{
- m_background = wxNullColour;
m_nFrames = 0;
}
- virtual ~wxAnimationDecoder() { }
-
virtual bool Load( wxInputStream& stream ) = 0;
- virtual bool CanRead( wxInputStream& stream ) const = 0;
+
+ bool CanRead( wxInputStream& stream ) const
+ {
+ // NOTE: this code is the same of wxImageHandler::CallDoCanRead
+
+ if ( !stream.IsSeekable() )
+ return false; // can't test unseekable stream
+
+ wxFileOffset posOld = stream.TellI();
+ bool ok = DoCanRead(stream);
+
+ // restore the old position to be able to test other formats and so on
+ if ( stream.SeekI(posOld) == wxInvalidOffset )
+ {
+ wxLogDebug(wxT("Failed to rewind the stream in wxAnimationDecoder!"));
+
+ // reading would fail anyhow as we're not at the right position
+ return false;
+ }
+
+ return ok;
+ }
virtual wxAnimationDecoder *Clone() const = 0;
virtual wxAnimationType GetType() const = 0;
unsigned int GetFrameCount() const { return m_nFrames; }
protected:
+ // checks the signature of the data in the given stream and returns true if it
+ // appears to be a valid animation format recognized by the animation decoder;
+ // this function should modify the stream current position without taking care
+ // of restoring it since CanRead() will do it.
+ virtual bool DoCanRead(wxInputStream& stream) const = 0;
+
wxSize m_szAnimation;
unsigned int m_nFrames;
wxColour m_background;
};
+#endif // wxUSE_STREAMS
-#endif // wxUSE_STREAM
#endif // _WX_ANIMDECOD_H