include/wx/gifdecod.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        gifdecod.h
   3 // Purpose:     wxGIFDecoder, GIF reader for wxImage and wxAnimation
   4 // Author:      Guillermo Rodriguez Garcia <guille@iies.es>
   5 // Version:     3.02
   6 // CVS-ID:      $Id$
   7 // Copyright:   (c) 1999 Guillermo Rodriguez Garcia
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_GIFDECOD_H
  12 #define _WX_GIFDECOD_H
  13
  14 #include "wx/defs.h"
  15
  16 #if wxUSE_STREAMS && wxUSE_GIF
  17
  18 #include "wx/stream.h"
  19 #include "wx/image.h"
  20 #include "wx/animdecod.h"
  21
  22 // internal utility used to store a frame in 8bit-per-pixel format
  23 class /*WXDLLEXPORT*/ GIFImage;
  24
  25
  26 // --------------------------------------------------------------------------
  27 // Constants
  28 // --------------------------------------------------------------------------
  29
  30 // Error codes:
  31 //  Note that the error code wxGIF_TRUNCATED means that the image itself
  32 //  is most probably OK, but the decoder didn't reach the end of the data
  33 //  stream; this means that if it was not reading directly from file,
  34 //  the stream will not be correctly positioned. the
  35 //
  36 enum wxGIFErrorCode
  37 {
  38     wxGIF_OK = 0,                   /* everything was OK */
  39     wxGIF_INVFORMAT,                /* error in gif header */
  40     wxGIF_MEMERR,                   /* error allocating memory */
  41     wxGIF_TRUNCATED                 /* file appears to be truncated */
  42 };
  43
  44 #define MAX_BLOCK_SIZE 256          /* max. block size */
  45
  46
  47 // --------------------------------------------------------------------------
  48 // wxGIFDecoder class
  49 // --------------------------------------------------------------------------
  50
  51 class WXDLLEXPORT wxGIFDecoder : public wxAnimationDecoder
  52 {
  53 private:
  54     // a wxArray provides a constant access time rather than a linear time
  55     // like for linked lists.
  56     wxArrayPtrVoid m_frames;
  57
  58     // decoder state vars
  59     int           m_restbits;       /* remaining valid bits */
  60     unsigned int  m_restbyte;       /* remaining bytes in this block */
  61     unsigned int  m_lastbyte;       /* last byte read */
  62     unsigned char m_buffer[MAX_BLOCK_SIZE];     /* buffer for reading */
  63     unsigned char *m_bufp;          /* pointer to next byte in buffer */
  64
  65 private:
  66     int getcode(wxInputStream& stream, int bits, int abfin);
  67     wxGIFErrorCode dgif(wxInputStream& stream, GIFImage *img, int interl, int bits);
  68
  69 public:
  70     // get data of current frame
  71     unsigned char* GetData(size_t frame) const;
  72     unsigned char* GetPalette(size_t frame) const;
  73     unsigned int GetNcolours(size_t frame) const;
  74     int GetTransparentColour(size_t frame) const;
  75
  76     virtual wxSize GetFrameSize(size_t frame) const;
  77     virtual wxPoint GetFramePosition(size_t frame) const;
  78     virtual wxAnimationDisposal GetDisposalMethod(size_t frame) const;
  79     virtual long GetDelay(size_t frame) const;
  80
  81     // GIFs can contain both static images and animations
  82     bool IsAnimation() const
  83         { return m_nFrames > 1; }
  84
  85 public:
  86     // constructor, destructor, etc.
  87     wxGIFDecoder();
  88     ~wxGIFDecoder();
  89
  90     // load function which returns more info than just Load():
  91     wxGIFErrorCode LoadGIF( wxInputStream& stream );
  92
  93     // free all internal frames
  94     void Destroy();
  95
  96 public:     // implementation of wxAnimationDecoder's pure virtuals
  97
  98     virtual bool CanRead( wxInputStream& stream ) const;
  99     virtual bool Load( wxInputStream& stream )
 100         { return LoadGIF(stream) == wxGIF_OK; }
 101
 102     bool ConvertToImage(size_t frame, wxImage *image) const;
 103
 104     wxAnimationDecoder *Clone() const
 105         { return new wxGIFDecoder; }
 106     wxAnimationType GetType() const
 107         { return wxANIMATION_TYPE_GIF; }
 108
 109 private:
 110     DECLARE_NO_COPY_CLASS(wxGIFDecoder)
 111 };
 112
 113
 114 #endif  // wxUSE_STREAM && wxUSE_GIF
 115 #endif  // _WX_GIFDECOD_H
 116