assimp/include/export.hpp

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/** @file  export.hpp
*  @brief Defines the CPP-API for the Assimp export interface
*/
#ifndef AI_EXPORT_HPP_INC
#define AI_EXPORT_HPP_INC

#ifndef ASSIMP_BUILD_NO_EXPORT

#include "export.h"

namespace Assimp	{
	class ExporterPimpl;


// ----------------------------------------------------------------------------------
/** CPP-API: The Exporter class forms an C++ interface to the export functionality 
 * of the Open Asset Import Library. Note that the export interface is available
 * only if Assimp has been built with ASSIMP_BUILD_NO_EXPORT not defined.
 * 
 * The interface is modelled after the importer interface and mostly
 * symmetric. The same rules for threading etc. apply.
 *
 * In a nutshell, there are two export interfaces: #Export, which writes the
 * output file(s) either to the regular file system or to a user-supplied 
 * #IOSystem, and #ExportToBlob which returns a linked list of memory
 * buffers (blob), each referring to one output file (in most cases
 * there will be only one output file of course, but this extra complexity is
 * needed since Assimp aims at supporting a wide range of file formats). 
 * 
 * #ExportToBlob is especially useful if you intend to work 
 * with the data in-memory. 
*/
class ASSIMP_API Exporter
	// TODO: causes good ol' base class has no dll interface warning
//#ifdef __cplusplus
//	: public boost::noncopyable
//#endif // __cplusplus
{
public:

	/** Function pointer type of a Export worker function */
	typedef void (*fpExportFunc)(const char*,IOSystem*,const aiScene*);

	/** Internal description of an Assimp export format option */
	struct ExportFormatEntry
	{
		/// Public description structure to be returned by aiGetExportFormatDescription()
		aiExportFormatDesc mDescription;

		// Worker function to do the actual exporting
		fpExportFunc mExportFunction;

		// Postprocessing steps to be executed PRIOR to invoking mExportFunction
		unsigned int mEnforcePP;

		// Constructor to fill all entries
		ExportFormatEntry( const char* pId, const char* pDesc, const char* pExtension, fpExportFunc pFunction, unsigned int pEnforcePP = 0u)
		{
			mDescription.id = pId;
			mDescription.description = pDesc;
			mDescription.fileExtension = pExtension;
			mExportFunction = pFunction;
			mEnforcePP = pEnforcePP;
		}

		ExportFormatEntry() : mExportFunction(), mEnforcePP() {}
	};


public:

	
	Exporter();
	~Exporter();

public:


	// -------------------------------------------------------------------
	/** Supplies a custom IO handler to the exporter to use to open and
	 * access files. 
	 * 
	 * If you need #Export to use custom IO logic to access the files, 
	 * you need to supply a custom implementation of IOSystem and 
	 * IOFile to the exporter. 
	 *
	 * #Exporter takes ownership of the object and will destroy it 
	 * afterwards. The previously assigned handler will be deleted.
	 * Pass NULL to take again ownership of your IOSystem and reset Assimp
	 * to use its default implementation, which uses plain file IO.
	 *
	 * @param pIOHandler The IO handler to be used in all file accesses 
	 *   of the Importer. */
	void SetIOHandler( IOSystem* pIOHandler);

	// -------------------------------------------------------------------
	/** Retrieves the IO handler that is currently set.
	 * You can use #IsDefaultIOHandler() to check whether the returned
	 * interface is the default IO handler provided by ASSIMP. The default
	 * handler is active as long the application doesn't supply its own
	 * custom IO handler via #SetIOHandler().
	 * @return A valid IOSystem interface, never NULL. */
	IOSystem* GetIOHandler() const;

	// -------------------------------------------------------------------
	/** Checks whether a default IO handler is active 
	 * A default handler is active as long the application doesn't 
	 * supply its own custom IO handler via #SetIOHandler().
	 * @return true by default */
	bool IsDefaultIOHandler() const;



	// -------------------------------------------------------------------
	/** Exports the given scene to a chosen file format. Returns the exported 
	* data as a binary blob which you can write into a file or something.
	* When you're done with the data, simply let the #Exporter instance go 
	* out of scope to have it released automatically.
	* @param pScene The scene to export. Stays in possession of the caller,
	*   is not changed by the function.
	* @param pFormatId ID string to specify to which format you want to 
	*   export to. Use 
	* #GetExportFormatCount / #GetExportFormatDescription to learn which 
	*   export formats are available.
	* @param pPreprocessing See the documentation for #Export
	* @return the exported data or NULL in case of error.
	* @note If the Exporter instance did already hold a blob from
	*   a previous call to #ExportToBlob, it will be disposed. 
	*   Any IO handlers set via #SetIOHandler are ignored here.*/
	const aiExportDataBlob* ExportToBlob(  const aiScene* pScene, const char* pFormatId, unsigned int pPreprocessing = 0u );
	inline const aiExportDataBlob* ExportToBlob(  const aiScene* pScene, const std::string& pFormatId, unsigned int pPreprocessing = 0u );


	// -------------------------------------------------------------------
	/** Convenience function to export directly to a file. Use
	 *  #SetIOSystem to supply a custom IOSystem to gain fine-grained control
	 *  about the output data flow of the export process.
	 * @param pBlob A data blob obtained from a previous call to #aiExportScene. Must not be NULL.
	 * @param pPath Full target file name. Target must be accessible.
	 * @param pPreprocessing Accepts any choice of the #aiPostProcessing enumerated
	 *   flags, but in reality only a subset of them makes sense here. Specifying
	 *   'preprocessing' flags is useful if the input scene does not conform to 
	 *   Assimp's default conventions as specified in the @link data Data Structures Page @endlink. 
	 *   In short, this means the geometry data should use a right-handed coordinate systems, face 
	 *   winding should be counter-clockwise and the UV coordinate origin is assumed to be in
	 *   the upper left. The #aiProcess_MakeLeftHanded, #aiProcess_FlipUVs and 
	 *   #aiProcess_FlipWindingOrder flags are used in the import side to allow users
	 *   to have those defaults automatically adapted to their conventions. Specifying those flags
	 *   for exporting has the opposite effect, respectively. Some other of the
	 *   #aiPostProcessSteps enumerated values may be useful as well, but you'll need
	 *   to try out what their effect on the exported file is. Many formats impose
	 *   their own restrictions on the structure of the geometry stored therein,
	 *   so some preprocessing may have little or no effect at all, or may be
	 *   redundant as exporters would apply them anyhow. A good example 
	 *   is triangulation - whilst you can enforce it by specifying
	 *   the #aiProcess_Triangulate flag, most export formats support only
	 *  triangulate data so they would run the step even if it wasn't requested.
	 * @return AI_SUCCESS if everything was fine. */
	aiReturn Export( const aiScene* pScene, const char* pFormatId, const char* pPath, unsigned int pPreprocessing = 0u);
	inline aiReturn Export( const aiScene* pScene, const std::string& pFormatId, const std::string& pPath,  unsigned int pPreprocessing = 0u);


	// -------------------------------------------------------------------
	/** Returns an error description of an error that occurred in #Export
	 *    or #ExportToBlob
	 *
	 * Returns an empty string if no error occurred.
	 * @return A description of the last error, an empty string if no 
	 *   error occurred. The string is never NULL.
	 *
	 * @note The returned function remains valid until one of the 
	 * following methods is called: #Export, #ExportToBlob, #FreeBlob */
	const char* GetErrorString() const;


	// -------------------------------------------------------------------
	/** Return the blob obtained from the last call to #ExportToBlob */
	const aiExportDataBlob* GetBlob() const;


	// -------------------------------------------------------------------
	/** Orphan the blob from the last call to #ExportToBlob. This means
	 *  the caller takes ownership and is thus responsible for calling
	 *  the C API function #aiReleaseExportBlob to release it. */
	const aiExportDataBlob* GetOrphanedBlob() const;


	// -------------------------------------------------------------------
	/** Frees the current blob.
	 *
	 *  The function does nothing if no blob has previously been 
	 *  previously produced via #ExportToBlob. #FreeBlob is called
	 *  automatically by the destructor. The only reason to call
	 *  it manually would be to reclain as much storage as possible
	 *  without giving up the #Exporter instance yet. */
	void FreeBlob( );


	// -------------------------------------------------------------------
	/** Returns the number of export file formats available in the current
	 *  Assimp build. Use #Exporter::GetExportFormatDescription to
	 *  retrieve infos of a specific export format */
	size_t GetExportFormatCount() const;


	// -------------------------------------------------------------------
	/** Returns a description of the nth export file format. Use #
	 *  #Exporter::GetExportFormatCount to learn how many export 
	 *  formats are supported. 
	 * @param pIndex Index of the export format to retrieve information 
	 *  for. Valid range is 0 to #Exporter::GetExportFormatCount
	 * @return A description of that specific export format. 
	 *  NULL if pIndex is out of range. */
	const aiExportFormatDesc* GetExportFormatDescription( size_t pIndex ) const;


	// -------------------------------------------------------------------
	/** Register a custom exporter. Custom export formats are limited to
	 *    to the current #Exporter instance and do not affect the
	 *    library globally.
	 *  @param desc Exporter description.
	 *  @return aiReturn_SUCCESS if the export format was successfully
	 *    registered. A common cause that would prevent an exporter
	 *    from being registered is that its format id is already
	 *    occupied by another format. */
	aiReturn RegisterExporter(const ExportFormatEntry& desc);


	// -------------------------------------------------------------------
	/** Remove an export format previously registered with #RegisterExporter
	 *  from the #Exporter instance (this can also be used to drop
	 *  builtin exporters because those are implicitly registered
	 *  using #RegisterExporter).
	 *  @param id Format id to be unregistered, this refers to the
	 *    'id' field of #aiExportFormatDesc. 
	 *  @note Calling this method on a format description not yet registered
	 *    has no effect.*/
	void UnregisterExporter(const char* id);


protected:

	// Just because we don't want you to know how we're hacking around.
	ExporterPimpl* pimpl;
};


// ----------------------------------------------------------------------------------
inline const aiExportDataBlob* Exporter :: ExportToBlob(  const aiScene* pScene, const std::string& pFormatId,unsigned int pPreprocessing ) 
{
	return ExportToBlob(pScene,pFormatId.c_str(),pPreprocessing);
}

// ----------------------------------------------------------------------------------
inline aiReturn Exporter :: Export( const aiScene* pScene, const std::string& pFormatId, const std::string& pPath, unsigned int pPreprocessing )
{
	return Export(pScene,pFormatId.c_str(),pPath.c_str(),pPreprocessing);
}

} // namespace Assimp
#endif // ASSIMP_BUILD_NO_EXPORT
#endif // AI_EXPORT_HPP_INC