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1 /////////////////////////////////////////////////////////////////////////////
2 // Name: wx/animdecod.h
3 // Purpose: wxAnimationDecoder
4 // Author: Francesco Montorsi
5 // CVS-ID: $Id$
6 // Copyright: (c) 2006 Francesco Montorsi
7 // Licence: wxWindows licence
8 /////////////////////////////////////////////////////////////////////////////
9
10 #ifndef _WX_ANIMDECOD_H
11 #define _WX_ANIMDECOD_H
12
13 #include "wx/defs.h"
14
15 #if wxUSE_STREAMS
16
17 #include "wx/colour.h"
18 #include "wx/gdicmn.h"
19 #include "wx/log.h"
20 #include "wx/stream.h"
21
22 class WXDLLIMPEXP_FWD_BASE wxInputStream;
23 class WXDLLIMPEXP_FWD_CORE wxImage;
24
25 /*
26
27 Differences between a wxAnimationDecoder and a wxImageHandler:
28
29 1) wxImageHandlers always load an input stream directly into a given wxImage
30 object converting from the format-specific data representation to the
31 wxImage native format (RGB24).
32 wxAnimationDecoders always load an input stream using some optimized format
33 to store it which is format-depedent. This allows to store a (possibly big)
34 animation using a format which is a good compromise between required memory
35 and time required to blit it on the screen.
36
37 2) wxAnimationDecoders contain the animation data in some internal variable.
38 That's why they derive from wxObjectRefData: they are data which can be shared.
39
40 3) wxAnimationDecoders can be used by a wxImageHandler to retrieve a frame
41 in wxImage format; the viceversa cannot be done.
42
43 4) wxAnimationDecoders are decoders only, thus they do not support save features.
44
45 5) wxAnimationDecoders are directly used by wxAnimation (generic implementation)
46 as wxObjectRefData while they need to be 'wrapped' by a wxImageHandler for
47 wxImage uses.
48
49 */
50
51
52 // --------------------------------------------------------------------------
53 // Constants
54 // --------------------------------------------------------------------------
55
56 // NB: the values of these enum items are not casual but coincide with the
57 // GIF disposal codes. Do not change them !!
58 enum wxAnimationDisposal
59 {
60 // No disposal specified. The decoder is not required to take any action.
61 wxANIM_UNSPECIFIED = -1,
62
63 // Do not dispose. The graphic is to be left in place.
64 wxANIM_DONOTREMOVE = 0,
65
66 // Restore to background color. The area used by the graphic must be
67 // restored to the background color.
68 wxANIM_TOBACKGROUND = 1,
69
70 // Restore to previous. The decoder is required to restore the area
71 // overwritten by the graphic with what was there prior to rendering the graphic.
72 wxANIM_TOPREVIOUS = 2
73 };
74
75 enum wxAnimationType
76 {
77 wxANIMATION_TYPE_INVALID,
78 wxANIMATION_TYPE_GIF,
79 wxANIMATION_TYPE_ANI,
80
81 wxANIMATION_TYPE_ANY
82 };
83
84
85 // --------------------------------------------------------------------------
86 // wxAnimationDecoder class
87 // --------------------------------------------------------------------------
88
89 class WXDLLIMPEXP_CORE wxAnimationDecoder : public wxObjectRefData
90 {
91 public:
92 wxAnimationDecoder()
93 {
94 m_nFrames = 0;
95 }
96
97 virtual bool Load( wxInputStream& stream ) = 0;
98
99 bool CanRead( wxInputStream& stream ) const
100 {
101 // NOTE: this code is the same of wxImageHandler::CallDoCanRead
102
103 if ( !stream.IsSeekable() )
104 return false; // can't test unseekable stream
105
106 wxFileOffset posOld = stream.TellI();
107 bool ok = DoCanRead(stream);
108
109 // restore the old position to be able to test other formats and so on
110 if ( stream.SeekI(posOld) == wxInvalidOffset )
111 {
112 wxLogDebug(wxT("Failed to rewind the stream in wxAnimationDecoder!"));
113
114 // reading would fail anyhow as we're not at the right position
115 return false;
116 }
117
118 return ok;
119 }
120
121 virtual wxAnimationDecoder *Clone() const = 0;
122 virtual wxAnimationType GetType() const = 0;
123
124 // convert given frame to wxImage
125 virtual bool ConvertToImage(unsigned int frame, wxImage *image) const = 0;
126
127
128 // frame specific data getters
129
130 // not all frames may be of the same size; e.g. GIF allows to
131 // specify that between two frames only a smaller portion of the
132 // entire animation has changed.
133 virtual wxSize GetFrameSize(unsigned int frame) const = 0;
134
135 // the position of this frame in case it's not as big as m_szAnimation
136 // or wxPoint(0,0) otherwise.
137 virtual wxPoint GetFramePosition(unsigned int frame) const = 0;
138
139 // what should be done after displaying this frame.
140 virtual wxAnimationDisposal GetDisposalMethod(unsigned int frame) const = 0;
141
142 // the number of milliseconds this frame should be displayed.
143 // if returns -1 then the frame must be displayed forever.
144 virtual long GetDelay(unsigned int frame) const = 0;
145
146 // the transparent colour for this frame if any or wxNullColour.
147 virtual wxColour GetTransparentColour(unsigned int frame) const = 0;
148
149 // get global data
150 wxSize GetAnimationSize() const { return m_szAnimation; }
151 wxColour GetBackgroundColour() const { return m_background; }
152 unsigned int GetFrameCount() const { return m_nFrames; }
153
154 protected:
155 // checks the signature of the data in the given stream and returns true if it
156 // appears to be a valid animation format recognized by the animation decoder;
157 // this function should modify the stream current position without taking care
158 // of restoring it since CanRead() will do it.
159 virtual bool DoCanRead(wxInputStream& stream) const = 0;
160
161 wxSize m_szAnimation;
162 unsigned int m_nFrames;
163
164 // this is the colour to use for the wxANIM_TOBACKGROUND disposal.
165 // if not specified by the animation, it's set to wxNullColour
166 wxColour m_background;
167 };
168
169 #endif // wxUSE_STREAMS
170
171 #endif // _WX_ANIMDECOD_H
172