DD::Image::GeoDescription Class Reference

#include <GeoReaderDescription.h>

Inheritance diagram for DD::Image::GeoDescription:

Public Types
typedef bool(*	FilenameTester) (const std::string &filename)
typedef bool(*	FilenameTesterExt) (const std::string &filename, std::string &errorOut)
typedef std::variant< std::monostate, FilenameTester, FilenameTesterExt >	FilenameTesterVariant
typedef GeoReader *(*	Constructor) (ReadGeo *, int fd, const unsigned char *buf, int bufsize)
typedef bool(*	Tester) (int fd, const unsigned char *buf, int bufsize)
typedef GeoReaderFormat *(*	GeoReaderFormatConstructor) (ReadGeo *)
Public Types inherited from DD::Image::Description
using	DescriptionList = std::vector< Description * >
using	NodeBuilder = std::function< Node *(void *)>

Public Member Functions
	GeoDescription (const char *n, Constructor c, GeoReaderFormatConstructor fmtConstructor, Tester t=nullptr, License *f=nullptr, bool needFd=true)
	GeoDescription (const char *n, Constructor c, GeoReaderFormatConstructor fmtConstructor, FilenameTester ft, License *f=nullptr, bool needFd=true)
	GeoDescription (const char *n, Constructor c, GeoReaderFormatConstructor fmtConstructor, FilenameTesterExt ft, License *f=nullptr, bool needFd=true)
Public Member Functions inherited from DD::Image::ReaderDescription
	ReaderDescription (const char *n, const char *l)

Static Public Member Functions
static const GeoDescription *	find (int i)
static const GeoDescription *	find (const char *name)
static FilenameTesterVariant	findFilenameTester (const GeoDescription *desc)
static bool	testFilename (const FilenameTesterVariant &tester, const std::string &filename, std::string &errorOut)
Static Public Member Functions inherited from DD::Image::ReaderDescription
static const Description *	find (const DescriptionList &list, const char *name, const char *pluginSuffix, const char *&triedPlugin)

Public Attributes
Constructor	_constructor
GeoReaderFormatConstructor	_format_constructor
Tester	_test
bool	_needFd
Public Attributes inherited from DD::Image::ReaderDescription
const char *	names
const char *	label
Public Attributes inherited from DD::Image::Description
const char *	compiled
const char *	plugin
License *	license

Static Public Attributes
static DD::Image::Description::DescriptionList	_collection

Additional Inherited Members
Protected Member Functions inherited from DD::Image::Description
void	ctor (void(*f)(Description *))
void	ctor (void(*f)(Description *), NodeBuilder nodeBuilder)

Detailed Description

This structure describes a subclass of GeoReader. The constructor builds these into a list that ReadGeo operators search to find a way to read a filename given to them.

Sample code for a plugin that defines a GeoReader:

class MyReader : public GeoReader {
static const Description d;
...
};
 
static GeoReader* build(int fd, const unsigned char* b, int n) {
return new MyReader(fd, b, n);
}
 
static bool test(int fd, const unsigned char *block, int) {
return (block[0] == MY_MAGIC_BYTE);
}
 
const GeoReader::Description MyReader::d("myf\0", "my file format", build, test);

Member Typedef Documentation

FilenameTester

typedef bool(* DD::Image::GeoDescription::FilenameTester) (const std::string &filename)

Filename tester: returns true if the reader claims the file

FilenameTesterExt

typedef bool(* DD::Image::GeoDescription::FilenameTesterExt) (const std::string &filename, std::string &errorOut)

Extended filename tester: returns true if the reader claims the file. If returning false it may populate 'errorOut' with a human readable reason which may be surfaced to the user when an explicit type was requested or no reader matched.

FilenameTesterVariant

typedef std::variant<std::monostate, FilenameTester, FilenameTesterExt> DD::Image::GeoDescription::FilenameTesterVariant

Type alias for the variant containing different filename tester types.

Constructor & Destructor Documentation

GeoDescription() [1/3]

DD::Image::GeoDescription::GeoDescription ( const char *  n, Constructor  c, GeoReaderFormatConstructor  fmtConstructor, Tester  t = nullptr, License *  f = nullptr, bool  needFd = true  )

inline

Simpler constructor that sets names and label to same value.

GeoDescription() [2/3]

DD::Image::GeoDescription::GeoDescription ( const char *  n, Constructor  c, GeoReaderFormatConstructor  fmtConstructor, FilenameTester  ft, License *  f = nullptr, bool  needFd = true  )

inline

This constructor takes a FilenameTester parameter. FilenameTester is a function pointer to test a file's compatibility with the reader using the given filename. This is an alternative to using GeoDescription::Tester which requires a file descriptor.

GeoDescription() [3/3]

DD::Image::GeoDescription::GeoDescription ( const char *  n, Constructor  c, GeoReaderFormatConstructor  fmtConstructor, FilenameTesterExt  ft, License *  f = nullptr, bool  needFd = true  )

inline

This constructor takes a FilenameTesterExt parameter. FilenameTesterExt is a function pointer to test a file's compatibility with the reader using the given filename. If the test fails, it can provide a human-readable error message. This is an alternative to using GeoDescription::Tester which requires a file descriptor.

Member Function Documentation

find() [1/2]

const GeoDescription * GeoDescription::find ( int  i )

static

Return the i'th GeoDescription known about, or return a null pointer for the last one.

References _collection.

find() [2/2]

const GeoDescription * GeoDescription::find ( const char *  name )

static

Search all the defined GeoDescriptions for one whose name matches the passed string, or return null pointer if none.

References _collection.

findFilenameTester()

GeoDescription::FilenameTesterVariant GeoDescription::findFilenameTester ( const GeoDescription *  desc )

static

Search all the defined FilenameTesters for one which is related to the passed /p desc, or return null variant if none. Returns a variant containing either FilenameTester or FilenameTesterExt.

testFilename()

bool GeoDescription::testFilename ( const FilenameTesterVariant &  tester, const std::string &  filename, std::string &  errorOut  )

static

Helper function to test a filename using a FilenameTesterVariant. Returns true if the tester accepts the file, false otherwise. If the tester is FilenameTesterExt and returns false, errorOut will contain the error message.

Member Data Documentation

_collection

DD::Image::Description::DescriptionList GeoDescription::_collection

static

A list of pointers to all possible Descriptions to be used for instantiation of geo plugins.

Referenced by find().

_constructor

Constructor DD::Image::GeoDescription::_constructor

Make an instance of the reader.

If test is not null then fd is an opened file, it is seeked to bufsize, and buf contains the first bufsize bytes of the file. You can use this data to store stuff into the info_ (however you cannot report error messages and filename() does not work yet).

_test

Tester DD::Image::GeoDescription::_test

If this pointer is non-null, it indicates a named Unix file is used to store the image. In this case Read will open the file and call this function. If it returns non-zero then the constructor will be called. This allows Read to poll all the Readers to see which one can read an unknown file format.

If this is null then zero is passed as the fd to the constructors.

buf points at the first bufsize characters of the file. bufsize is at least 512. If necessary you can mess with the fd, but be sure to seek it back to bufsize.

_needFd

bool DD::Image::GeoDescription::_needFd

whether or not the file descriptor is really needed (defaults to true)

if false then any open FD on the file will be closed before build is called, and -1 passed in