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 #ifdef __GNUG__
  15 #pragma interface "gifdecod.h"
  16 #endif
  17
  18 #include "wx/setup.h"
  19
  20 #if wxUSE_STREAMS && wxUSE_GIF
  21
  22 #include "wx/stream.h"
  23 #include "wx/image.h"
  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
  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 // Disposal method
  45 //  Experimental; subject to change.
  46 //
  47 enum
  48 {
  49     wxGIF_D_UNSPECIFIED = -1,       /* not specified */
  50     wxGIF_D_DONOTDISPOSE = 0,       /* do not dispose */
  51     wxGIF_D_TOBACKGROUND = 1,       /* restore to background colour */
  52     wxGIF_D_TOPREVIOUS = 2          /* restore to previous image */
  53 };
  54
  55
  56 #define MAX_BLOCK_SIZE 256          /* max. block size */
  57
  58
  59 // --------------------------------------------------------------------------
  60 // wxGIFDecoder class
  61 // --------------------------------------------------------------------------
  62
  63 // internal class for storing GIF image data
  64 class GIFImage
  65 {
  66 public:
  67     unsigned int w;                 /* width */
  68     unsigned int h;                 /* height */
  69     unsigned int left;              /* x coord (in logical screen) */
  70     unsigned int top;               /* y coord (in logical screen) */
  71     int transparent;                /* transparent color (-1 = none) */
  72     int disposal;                   /* disposal method (-1 = unspecified) */
  73     long delay;                     /* delay in ms (-1 = unused) */
  74     unsigned char *p;               /* bitmap */
  75     unsigned char *pal;             /* palette */
  76     GIFImage *next;                 /* next image */
  77     GIFImage *prev;                 /* prev image */
  78 };
  79
  80
  81 class WXDLLEXPORT wxGIFDecoder
  82 {
  83 private:
  84     // logical screen
  85     unsigned int  m_screenw;        /* logical screen width */
  86     unsigned int  m_screenh;        /* logical screen height */
  87     int           m_background;     /* background color (-1 = none) */
  88
  89     // image data
  90     bool          m_anim;           /* animated GIF */
  91     int           m_nimages;        /* number of images */
  92     int           m_image;          /* current image */
  93     GIFImage      *m_pimage;        /* pointer to current image */
  94     GIFImage      *m_pfirst;        /* pointer to first image */
  95     GIFImage      *m_plast;         /* pointer to last image */
  96
  97     // decoder state vars
  98     int           m_restbits;       /* remaining valid bits */
  99     unsigned int  m_restbyte;       /* remaining bytes in this block */
 100     unsigned int  m_lastbyte;       /* last byte read */
 101     unsigned char m_buffer[MAX_BLOCK_SIZE];     /* buffer for reading */
 102     unsigned char *m_bufp;          /* pointer to next byte in buffer */
 103
 104     // input stream
 105     wxInputStream *m_f;             /* input stream */
 106
 107 private:
 108     int getcode(int bits, int abfin);
 109     int dgif(GIFImage *img, int interl, int bits);
 110
 111 protected:
 112     // get data of current frame
 113     int GetFrameIndex() const;
 114     unsigned char* GetData() const;
 115     unsigned char* GetPalette() const;
 116     unsigned int GetWidth() const;
 117     unsigned int GetHeight() const;
 118     unsigned int GetLeft() const;
 119     unsigned int GetTop() const;
 120     int GetDisposalMethod() const;
 121     int GetTransparentColour() const;
 122     long GetDelay() const;
 123
 124     // get global data
 125     unsigned int GetLogicalScreenWidth() const;
 126     unsigned int GetLogicalScreenHeight() const;
 127     int GetBackgroundColour() const;
 128     int GetNumberOfFrames() const;
 129     bool IsAnimation() const;
 130
 131     // move through the animation
 132     bool GoFirstFrame();
 133     bool GoLastFrame();
 134     bool GoNextFrame(bool cyclic = FALSE);
 135     bool GoPrevFrame(bool cyclic = FALSE);
 136     bool GoFrame(int which);
 137
 138 public:
 139     // constructor, destructor, etc.
 140     wxGIFDecoder(wxInputStream *s, bool anim = FALSE);
 141     ~wxGIFDecoder();
 142     bool CanRead();
 143     int ReadGIF();
 144     void Destroy();
 145
 146     // convert current frame to wxImage
 147     bool ConvertToImage(wxImage *image) const;
 148 };
 149
 150
 151 #endif  // wxUSE_STREAM && wxUSE_GIF
 152 #endif  // _WX_GIFDECOD_H
 153