This is an abstract base class that defines the interface for reading image files of various types. More...

#include "pnmReader.h"

Inheritance diagram for PNMReader:

Public Member Functions
PNMFileType *	get_type () const
	Returns a pointer to the PNMFileType object that created this PNMReader. More...

virtual bool	is_floating_point ()
	Returns true if this PNMFileType represents a floating-point image type, false if it is a normal, integer type. More...

bool	is_valid () const
	Returns true if the PNMReader can be used to read data, false if something is wrong. More...

virtual void	prepare_read ()
	This method will be called before read_data() or read_row() is called. More...

virtual int	read_data (xel array, xelval alpha)
	Reads in an entire image all at once, storing it in the pre-allocated _x_size * _y_size array and alpha pointers. More...

virtual bool	read_pfm (PfmFile &pfm)
	Reads floating-point data directly into the indicated PfmFile. More...

virtual bool	read_row (xel array, xelval alpha, int x_size, int y_size)
	If supports_read_row(), above, returns true, this function may be called repeatedly to read the image, one horizontal row at a time, beginning from the top. More...

void	set_read_size (int x_size, int y_size)
	Instructs the reader to attempt to scale the image to the indicated size while reading it. More...

virtual bool	supports_read_row () const
	Returns true if this particular PNMReader is capable of returning the data one row at a time, via repeated calls to read_row(). More...

virtual bool	supports_stream_read () const
	Returns true if this particular PNMReader can read from a general stream (including pipes, etc.), or false if the reader must occasionally fseek() on its input stream, and thus only disk streams are supported. More...

Public Member Functions inherited from PNMImageHeader
	PNMImageHeader (const PNMImageHeader &copy)

ColorSpace	get_color_space () const

ColorType	get_color_type () const
	Returns the image type of the image, as an enumerated value. More...

std::string	get_comment () const

xelval	get_maxval () const

int	get_num_channels () const

LVecBase2i	get_size () const

PNMFileType *	get_type () const

int	get_x_size () const
	Returns the number of pixels in the X direction. More...

int	get_y_size () const
	Returns the number of pixels in the Y direction. More...

bool	has_alpha () const
	Returns true if the image includes an alpha channel, false otherwise. More...

bool	has_type () const

bool	is_grayscale () const
	Returns false if the image is a full-color image, and has red, green, and blue components; true if it is a grayscale image and has only a gray component. More...

PNMReader *	make_reader (const Filename &filename, PNMFileType *type=nullptr, bool report_unknown_type=true) const
	Returns a newly-allocated PNMReader of the suitable type for reading from the indicated image filename, or NULL if the filename cannot be read for some reason. More...

PNMReader *	make_reader (std::istream file, bool owns_file=true, const Filename &filename=Filename(), std::string magic_number=std::string(), PNMFileType type=nullptr, bool report_unknown_type=true) const
	Returns a newly-allocated PNMReader of the suitable type for reading from the already-opened image file, or NULL if the file cannot be read for some reason. More...

PNMWriter *	make_writer (const Filename &filename, PNMFileType *type=nullptr) const
	Returns a newly-allocated PNMWriter of the suitable type for writing an image to the indicated filename, or NULL if the filename cannot be written for some reason. More...

PNMWriter *	make_writer (std::ostream file, bool owns_file=true, const Filename &filename=Filename(), PNMFileType type=nullptr) const
	Returns a newly-allocated PNMWriter of the suitable type for writing to the already-opened image file, or NULL if the file cannot be written for some reason. More...

void	operator= (const PNMImageHeader &copy)

void	output (std::ostream &out) const

bool	read_header (const Filename &filename, PNMFileType *type=nullptr, bool report_unknown_type=true)
	Opens up the image file and tries to read its header information to determine its size, number of channels, etc. More...

bool	read_header (std::istream &data, const std::string &filename=std::string(), PNMFileType *type=nullptr, bool report_unknown_type=true)
	Reads the image header information only from the indicated stream. More...

void	set_comment (const std::string &comment)

void	set_type (PNMFileType *type)
	Sets the file type of this PNMImage. More...

Additional Inherited Members
Public Types inherited from PNMImageHeader
enum	ColorType { CT_invalid = 0, CT_grayscale = 1, CT_two_channel = 2, CT_color = 3, CT_four_channel = 4 }

typedef pmap< PixelSpec, int >	HistMap

typedef pvector< PixelSpec >	Palette

typedef pvector< PixelSpecCount >	PixelCount

Static Public Member Functions inherited from PNMImageHeader
static bool	has_alpha (ColorType color_type)
	This static variant of has_alpha() returns true if the indicated image type includes an alpha channel, false otherwise. More...

static bool	is_grayscale (ColorType color_type)
	This static variant of is_grayscale() returns true if the indicated image type represents a grayscale image, false otherwise. More...

static bool	read_magic_number (std::istream *file, std::string &magic_number, int num_bytes)
	Ensures that the first n bytes of the file are read into magic_number. More...

Public Attributes inherited from PNMImageHeader
	get_color_space
	Returns the color space that the image is encoded in, or CS_unspecified if unknown. More...

	get_comment
	Gets the user comment from the file. More...

	get_maxval
	Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image. More...

	get_num_channels
	Returns the number of channels in the image. More...

	get_size
	Returns the number of pixels in each direction. More...

	get_type
	If the file type is known (e.g. More...

	has_type
	Returns true if the PNMImageHeader knows what type it is, false otherwise. More...

	set_comment
	Writes a user comment string to the image (header). More...

Detailed Description

This is an abstract base class that defines the interface for reading image files of various types.

Any particular image file type that can be read must define a class that inherits from PNMReader to read it.

Definition at line 27 of file pnmReader.h.

Member Function Documentation

◆ get_type()

PNMFileType * PNMReader::get_type ( ) const

inline

Returns a pointer to the PNMFileType object that created this PNMReader.

Definition at line 44 of file pnmReader.I.

◆ is_floating_point()

bool PNMReader::is_floating_point ( )

virtual

Returns true if this PNMFileType represents a floating-point image type, false if it is a normal, integer type.

If this returns true, read_pfm() is implemented instead of read_data().

Reimplemented in PNMFileTypePfm::Reader.

Definition at line 71 of file pnmReader.cxx.

Referenced by PfmFile::read(), and PNMImage::read().

◆ is_valid()

bool PNMReader::is_valid ( ) const

inline

Returns true if the PNMReader can be used to read data, false if something is wrong.

Definition at line 53 of file pnmReader.I.

Referenced by PfmFile::read(), PNMImage::read(), and read_data().

◆ prepare_read()

void PNMReader::prepare_read ( )

virtual

This method will be called before read_data() or read_row() is called.

It instructs the reader to initialize its data structures as necessary to actually perform the read operation.

After this call, _x_size and _y_size should reflect the actual size that will be filled by read_data() (as possibly modified by set_read_size()).

Definition at line 44 of file pnmReader.cxx.

References supports_read_row().

Referenced by PNMImage::read().

◆ read_data()

int PNMReader::read_data	(	xel *	array,
		xelval *	alpha
	)

virtual

Reads in an entire image all at once, storing it in the pre-allocated _x_size * _y_size array and alpha pointers.

(If the image type has no alpha channel, alpha is ignored.) Returns the number of rows correctly read.

Derived classes need not override this if they instead provide supports_read_row() and read_row(), below.

Definition at line 94 of file pnmReader.cxx.

References Thread::consider_yield(), PNMImageHeader::has_alpha(), is_valid(), and read_row().

Referenced by PNMImage::read().

◆ read_pfm()

bool PNMReader::read_pfm ( PfmFile & pfm )

virtual

Reads floating-point data directly into the indicated PfmFile.

Returns true on success, false on failure.

Reimplemented in PNMFileTypePfm::Reader.

Definition at line 80 of file pnmReader.cxx.

Referenced by PfmFile::read(), and PNMImage::read().

◆ read_row()

bool PNMReader::read_row	(	xel *	array,
		xelval *	alpha,
		int	x_size,
		int	y_size
	)

virtual

If supports_read_row(), above, returns true, this function may be called repeatedly to read the image, one horizontal row at a time, beginning from the top.

Returns true if the row is successfully read, false if there is an error or end of file.

The x_size and y_size parameters are the value of _x_size and _y_size as originally filled in by the constructor; it is the actual number of pixels in the image. (The _x_size and _y_size members may have been automatically modified by the time this method is called if we are scaling on load, so should not be used.)

Definition at line 224 of file pnmReader.cxx.

Referenced by read_data().

◆ set_read_size()

void PNMReader::set_read_size	(	int	x_size,
		int	y_size
	)

inline

Instructs the reader to attempt to scale the image to the indicated size while reading it.

The reader may or may not follow this suggestion, or may follow it only partially (e.g. by reading a file which is slightly reduced in size, but not the precise size requested).

Definition at line 34 of file pnmReader.I.

Referenced by PNMImage::read().

◆ supports_read_row()

bool PNMReader::supports_read_row ( ) const

virtual

Returns true if this particular PNMReader is capable of returning the data one row at a time, via repeated calls to read_row().

Returns false if the only way to read from this file is all at once, via read_data().

Definition at line 207 of file pnmReader.cxx.

Referenced by prepare_read().

◆ supports_stream_read()

bool PNMReader::supports_stream_read ( ) const

virtual

Returns true if this particular PNMReader can read from a general stream (including pipes, etc.), or false if the reader must occasionally fseek() on its input stream, and thus only disk streams are supported.

Definition at line 235 of file pnmReader.cxx.

The documentation for this class was generated from the following files:

panda/src/pnmimage/pnmReader.h
panda/src/pnmimage/pnmReader.cxx
panda/src/pnmimage/pnmReader.I

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ get_type()

◆ is_floating_point()

◆ is_valid()

◆ prepare_read()

◆ read_data()

◆ read_pfm()

◆ read_row()

◆ set_read_size()

◆ supports_read_row()

◆ supports_stream_read()