28c3605f6b
Resolve the long standing "NOTE" comments about having the same code in wxAnimationDecoder::CanRead(), wxImage::CanRead() and GetImageCount() by extracting the common logic into a helper wxInputStreamPeeker class and using it from all places. This loses the possibility to log a debug message if rewinding the stream fails, but this is probably not very valuable and the actual error should be already logged by SeekI() itself when it fails on a seekable stream. No real changes.
155 lines
5.1 KiB
C++
155 lines
5.1 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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// Name: wx/animdecod.h
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// Purpose: wxAnimationDecoder
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// Author: Francesco Montorsi
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// Copyright: (c) 2006 Francesco Montorsi
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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#ifndef _WX_ANIMDECOD_H
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#define _WX_ANIMDECOD_H
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#include "wx/defs.h"
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#if wxUSE_STREAMS
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#include "wx/colour.h"
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#include "wx/gdicmn.h"
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#include "wx/log.h"
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#include "wx/stream.h"
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class WXDLLIMPEXP_FWD_CORE wxImage;
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/*
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Differences between a wxAnimationDecoder and a wxImageHandler:
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1) wxImageHandlers always load an input stream directly into a given wxImage
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object converting from the format-specific data representation to the
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wxImage native format (RGB24).
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wxAnimationDecoders always load an input stream using some optimized format
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to store it which is format-dependent. This allows to store a (possibly big)
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animation using a format which is a good compromise between required memory
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and time required to blit it on the screen.
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2) wxAnimationDecoders contain the animation data in some internal variable.
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That's why they derive from wxObjectRefData: they are data which can be shared.
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3) wxAnimationDecoders can be used by a wxImageHandler to retrieve a frame
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in wxImage format; the viceversa cannot be done.
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4) wxAnimationDecoders are decoders only, thus they do not support save features.
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5) wxAnimationDecoders are directly used by wxAnimation (generic implementation)
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as wxObjectRefData while they need to be 'wrapped' by a wxImageHandler for
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wxImage uses.
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*/
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// --------------------------------------------------------------------------
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// Constants
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// --------------------------------------------------------------------------
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// NB: the values of these enum items are not casual but coincide with the
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// GIF disposal codes. Do not change them !!
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enum wxAnimationDisposal
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{
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// No disposal specified. The decoder is not required to take any action.
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wxANIM_UNSPECIFIED = -1,
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// Do not dispose. The graphic is to be left in place.
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wxANIM_DONOTREMOVE = 0,
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// Restore to background color. The area used by the graphic must be
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// restored to the background color.
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wxANIM_TOBACKGROUND = 1,
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// Restore to previous. The decoder is required to restore the area
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// overwritten by the graphic with what was there prior to rendering the graphic.
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wxANIM_TOPREVIOUS = 2
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};
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enum wxAnimationType
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{
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wxANIMATION_TYPE_INVALID,
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wxANIMATION_TYPE_GIF,
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wxANIMATION_TYPE_ANI,
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wxANIMATION_TYPE_ANY
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};
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// --------------------------------------------------------------------------
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// wxAnimationDecoder class
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// --------------------------------------------------------------------------
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class WXDLLIMPEXP_CORE wxAnimationDecoder : public wxObjectRefData
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{
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public:
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wxAnimationDecoder()
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{
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m_nFrames = 0;
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}
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virtual bool Load( wxInputStream& stream ) = 0;
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bool CanRead( wxInputStream& stream ) const
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{
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return wxInputStreamPeeker(stream).
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CallIfCanSeek(&wxAnimationDecoder::DoCanRead, this);
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}
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virtual wxAnimationDecoder *Clone() const = 0;
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virtual wxAnimationType GetType() const = 0;
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// convert given frame to wxImage
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virtual bool ConvertToImage(unsigned int frame, wxImage *image) const = 0;
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// frame specific data getters
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// not all frames may be of the same size; e.g. GIF allows to
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// specify that between two frames only a smaller portion of the
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// entire animation has changed.
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virtual wxSize GetFrameSize(unsigned int frame) const = 0;
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// the position of this frame in case it's not as big as m_szAnimation
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// or wxPoint(0,0) otherwise.
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virtual wxPoint GetFramePosition(unsigned int frame) const = 0;
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// what should be done after displaying this frame.
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virtual wxAnimationDisposal GetDisposalMethod(unsigned int frame) const = 0;
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// the number of milliseconds this frame should be displayed.
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// if returns -1 then the frame must be displayed forever.
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virtual long GetDelay(unsigned int frame) const = 0;
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// the transparent colour for this frame if any or wxNullColour.
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virtual wxColour GetTransparentColour(unsigned int frame) const = 0;
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// get global data
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wxSize GetAnimationSize() const { return m_szAnimation; }
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wxColour GetBackgroundColour() const { return m_background; }
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unsigned int GetFrameCount() const { return m_nFrames; }
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protected:
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// checks the signature of the data in the given stream and returns true if it
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// appears to be a valid animation format recognized by the animation decoder;
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// this function should modify the stream current position without taking care
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// of restoring it since CanRead() will do it.
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virtual bool DoCanRead(wxInputStream& stream) const = 0;
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wxSize m_szAnimation;
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unsigned int m_nFrames;
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// this is the colour to use for the wxANIM_TOBACKGROUND disposal.
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// if not specified by the animation, it's set to wxNullColour
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wxColour m_background;
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};
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#endif // wxUSE_STREAMS
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#endif // _WX_ANIMDECOD_H
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