X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/7776d70e7fa18301cfee34b5b60f127ba0781580..ab67e8874db324fab5223cc8d5dff8a8de3e2b77:/include/wx/animdecod.h?ds=inline diff --git a/include/wx/animdecod.h b/include/wx/animdecod.h index 5379c366a5..876c802520 100644 --- a/include/wx/animdecod.h +++ b/include/wx/animdecod.h @@ -16,8 +16,9 @@ #include "wx/colour.h" #include "wx/gdicmn.h" +#include "wx/log.h" +#include "wx/stream.h" -class WXDLLIMPEXP_FWD_BASE wxInputStream; class WXDLLIMPEXP_FWD_CORE wxImage; /* @@ -30,15 +31,15 @@ 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 @@ -61,11 +62,11 @@ enum wxAnimationDisposal // 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 }; @@ -93,7 +94,28 @@ public: } 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; @@ -129,6 +151,12 @@ public: 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;