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document that CanRead() and GetImageCount() functions of wxImageHandlers do NOT modify the current stream position and that they require seekable streams; rename current GetImageCount() functions to DoGetImageCount() and put save-and-restore stream position logic in GetImageCount(); add comments in the various DoCanRead() and in DoGetImageCount() where the stream position is modified; remove unneeded SeekI(0) calls from DoCanRead() and DoGetImageCount() functions: they didn't allow to load images from non-seekable streams; implement forward-seeking in wxInputStream::SeekI() also for non-seekable streams

Browse Source 
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60852 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Francesco Montorsi
2009-06-01 11:43:36 +00:00
parent 1f51673bb8
commit 8faef7ccbc
25 changed files with 236 additions and 93 deletions
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6
include/wx/anidecod.h
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@@ -44,7 +44,7 @@ public:
virtual wxColour GetTransparentColour(unsigned int frame) const;
// implementation of wxAnimationDecoder's pure virtuals
virtual bool CanRead( wxInputStream& stream ) const;
virtual bool Load( wxInputStream& stream );
bool ConvertToImage(unsigned int frame, wxImage *image) const;
@@ -55,6 +55,10 @@ public:
{ return wxANIMATION_TYPE_ANI; }
private:
// wxAnimationDecoder pure virtual:
virtual bool DoCanRead( wxInputStream& stream ) const;
// modifies current stream position (see wxAnimationDecoder::CanRead)
// frames stored as wxImage(s): ANI files are meant to be used mostly for animated
// cursors and thus they do not use any optimization to encode differences between
// two frames: they are just a list of images to display sequentially.

29
include/wx/animdecod.h
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@@ -93,7 +93,28 @@ 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(_T("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 +150,12 @@ 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;

14
include/wx/gifdecod.h
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@@ -76,7 +76,6 @@ public:
void Destroy();
// implementation of wxAnimationDecoder's pure virtuals
virtual bool CanRead( wxInputStream& stream ) const;
virtual bool Load( wxInputStream& stream )
{ return LoadGIF(stream) == wxGIF_OK; }
@@ -88,6 +87,15 @@ public:
{ return wxANIMATION_TYPE_GIF; }
private:
// wxAnimationDecoder pure virtual
virtual bool DoCanRead( wxInputStream& stream ) const;
// modifies current stream position (see wxAnimationDecoder::CanRead)
int getcode(wxInputStream& stream, int bits, int abfin);
wxGIFErrorCode dgif(wxInputStream& stream,
GIFImage *img, int interl, int bits);
// array of all frames
wxArrayPtrVoid m_frames;
@@ -98,10 +106,6 @@ private:
unsigned char m_buffer[256]; // buffer for reading
unsigned char *m_bufp; // pointer to next byte in buffer
int getcode(wxInputStream& stream, int bits, int abfin);
wxGIFErrorCode dgif(wxInputStream& stream,
GIFImage *img, int interl, int bits);
wxDECLARE_NO_COPY_CLASS(wxGIFDecoder);
};

6
include/wx/imagbmp.h
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@@ -89,8 +89,9 @@ public:
virtual bool SaveFile( wxImage *image, wxOutputStream& stream, bool verbose=true );
virtual bool LoadFile( wxImage *image, wxInputStream& stream, bool verbose=true, int index=-1 );
virtual bool DoLoadFile( wxImage *image, wxInputStream& stream, bool verbose, int index );
virtual int GetImageCount( wxInputStream& stream );
protected:
virtual int DoGetImageCount( wxInputStream& stream );
virtual bool DoCanRead( wxInputStream& stream );
#endif // wxUSE_STREAMS
@@ -145,8 +146,9 @@ public:
#if wxUSE_STREAMS
virtual bool SaveFile( wxImage *WXUNUSED(image), wxOutputStream& WXUNUSED(stream), bool WXUNUSED(verbose=true) ){return false ;}
virtual bool LoadFile( wxImage *image, wxInputStream& stream, bool verbose=true, int index=-1 );
virtual int GetImageCount( wxInputStream& stream );
protected:
virtual int DoGetImageCount( wxInputStream& stream );
virtual bool DoCanRead( wxInputStream& stream );
#endif // wxUSE_STREAMS

20
include/wx/image.h
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@@ -97,10 +97,17 @@ public:
{ }
#if wxUSE_STREAMS
virtual bool LoadFile( wxImage *image, wxInputStream& stream, bool verbose=true, int index=-1 );
virtual bool SaveFile( wxImage *image, wxOutputStream& stream, bool verbose=true );
// NOTE: LoadFile and SaveFile are not pure virtuals to allow derived classes
// to implement only one of the two
virtual bool LoadFile( wxImage *WXUNUSED(image), wxInputStream& WXUNUSED(stream),
bool WXUNUSED(verbose)=true, int WXUNUSED(index)=-1 )
{ return false; }
virtual bool SaveFile( wxImage *WXUNUSED(image), wxOutputStream& WXUNUSED(stream),
bool WXUNUSED(verbose)=true )
{ return false; }
virtual int GetImageCount( wxInputStream& stream );
int GetImageCount( wxInputStream& stream );
// save the stream position, call DoGetImageCount() and restore the position
bool CanRead( wxInputStream& stream ) { return CallDoCanRead(stream); }
bool CanRead( const wxString& name );
@@ -125,6 +132,13 @@ public:
protected:
#if wxUSE_STREAMS
// NOTE: this function is allowed to change the current stream position
// since GetImageCount() will take care of restoring it later
virtual int DoGetImageCount( wxInputStream& WXUNUSED(stream) )
{ return 1; } // default return value is 1 image
// NOTE: this function is allowed to change the current stream position
// since CallDoCanRead() will take care of restoring it later
virtual bool DoCanRead( wxInputStream& stream ) = 0;
// save the stream position, call DoCanRead() and restore the position

3
include/wx/imaggif.h
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@@ -35,8 +35,9 @@ public:
bool verbose = true, int index = -1);
virtual bool SaveFile(wxImage *image, wxOutputStream& stream,
bool verbose=true);
virtual int GetImageCount(wxInputStream& stream);
protected:
virtual int DoGetImageCount(wxInputStream& stream);
virtual bool DoCanRead(wxInputStream& stream);
#endif // wxUSE_STREAMS

3
include/wx/imagtiff.h
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@@ -34,8 +34,9 @@ public:
#if wxUSE_STREAMS
virtual bool LoadFile( wxImage *image, wxInputStream& stream, bool verbose=true, int index=-1 );
virtual bool SaveFile( wxImage *image, wxOutputStream& stream, bool verbose=true );
virtual int GetImageCount( wxInputStream& stream );
protected:
virtual int DoGetImageCount( wxInputStream& stream );
virtual bool DoCanRead( wxInputStream& stream );
#endif

7
include/wx/xpmdecod.h
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@@ -30,15 +30,20 @@ public:
#if wxUSE_STREAMS
// Is the stream XPM file?
// NOTE: this function modifies the current stream position
bool CanRead(wxInputStream& stream);
// Read XPM file from the stream, parse it and create image from it
wxImage ReadFile(wxInputStream& stream);
#endif
// Read directly from XPM data (as passed to wxBitmap ctor):
wxImage ReadData(const char* const* xpm_data);
#ifdef __BORLANDC__
// needed for Borland 5.5
wxImage ReadData(char** xpm_data) { return ReadData(const_cast<const char* const*>(xpm_data)); }
wxImage ReadData(char** xpm_data)
{ return ReadData(const_cast<const char* const*>(xpm_data)); }
#endif
};