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PNMImageHeader Class Reference

This is the base class of PNMImage, PNMReader, and PNMWriter. More...

#include <pnmImageHeader.h>

Inheritance diagram for PNMImageHeader:


Public Types
enum	ColorType { CT_invalid = 0, CT_grayscale = 1, CT_two_channel = 2, CT_color = 3, CT_four_channel = 4 }
Public Member Functions
	PNMImageHeader ()
	PNMImageHeader (const PNMImageHeader &copy)
void	operator= (const PNMImageHeader &copy)
	~PNMImageHeader ()
ColorType	get_color_type () const
	Returns the image type of the image, as an enumerated value.
int	get_num_channels () const
	Returns the number of channels in the image.
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.
bool	has_alpha () const
	Returns true if the image includes an alpha channel, false otherwise.
xelval	get_maxval () const
	Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image.
int	get_x_size () const
	Returns the number of pixels in the X direction.
int	get_y_size () const
	Returns the number of pixels in the Y direction.
bool	has_type () const
	Returns true if the PNMImageHeader knows what type it is, false otherwise.
PNMFileType *	get_type () const
	If the file type is known (e.g.
void	set_type (PNMFileType *type)
	Sets the file type of this PNMImage.
bool	read_header (const Filename &filename, PNMFileType *type=NULL)
	Opens up the image file and tries to read its header information to determine its size, number of channels, etc.
PNMReader *	make_reader (const Filename &filename, PNMFileType *type=NULL) 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.
PNMReader *	make_reader (istream file, bool owns_file=true, const Filename &filename=Filename(), string magic_number=string(), PNMFileType type=NULL) 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.
PNMWriter *	make_writer (const Filename &filename, PNMFileType *type=NULL) 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.
PNMWriter *	make_writer (ostream file, bool owns_file=true, const Filename &filename=Filename(), PNMFileType type=NULL) 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.
void	output (ostream &out) const
Static Public Member Functions
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.
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.
bool	read_magic_number (istream *file, string &magic_number, int num_bytes)
	Ensures that the first n bytes of the file are read into magic_number.
Protected Attributes
int	_x_size
int	_y_size
int	_num_channels
xelval	_maxval
PNMFileType *	_type

Detailed Description

This is the base class of PNMImage, PNMReader, and PNMWriter.

It encapsulates all the information associated with an image that describes its size, number of channels, etc; that is, all the information about the image except the image data itself. It's the sort of information you typically read from the image file's header.

Definition at line 55 of file pnmImageHeader.h.

Member Enumeration Documentation

enum PNMImageHeader::ColorType

Enumeration values:

CT_invalid

CT_grayscale

CT_two_channel

CT_color

CT_four_channel

Definition at line 65 of file pnmImageHeader.h.

Constructor & Destructor Documentation

PNMImageHeader::PNMImageHeader ( ) [inline]

Definition at line 30 of file pnmImageHeader.I.
References _type, and NULL.

PNMImageHeader::PNMImageHeader ( const PNMImageHeader & copy ) [inline]

Definition at line 46 of file pnmImageHeader.I.

PNMImageHeader::~PNMImageHeader ( ) [inline]

Definition at line 79 of file pnmImageHeader.I.
References _num_channels, CT_invalid, and nassertr.

Member Function Documentation

PNMImageHeader::ColorType PNMImageHeader::get_color_type ( ) const [inline]

Returns the image type of the image, as an enumerated value.
This is really just the number of channels cast to the enumerated type.
Definition at line 95 of file pnmImageHeader.I.
References CT_grayscale, CT_two_channel, and INLINE.
Referenced by get_num_channels(), PNMImage::write(), and PixelBuffer::write().

xelval PNMImageHeader::get_maxval ( ) const [inline]

Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image.
A pixel with this value is full on.
Definition at line 203 of file pnmImageHeader.I.
References _type.
Referenced by PNMImage::clamp_val(), PNMImage::fill(), PNMImage::operator=(), and PNMImage::~PNMImage().

int PNMImageHeader::get_num_channels ( ) const [inline]

Returns the number of channels in the image.

Definition at line 109 of file pnmImageHeader.I.
References get_color_type(), INLINE, and is_grayscale().
Referenced by PixelBuffer::write().

PNMFileType * PNMImageHeader::get_type ( void ) const [inline]

If the file type is known (e.g.
has_type() returns true), returns its PNMFileType pointer; otherwise, returns NULL.
Reimplemented in PNMReader, and PNMWriter.
Definition at line 269 of file pnmImageHeader.I.

int PNMImageHeader::get_x_size ( ) const [inline]

Returns the number of pixels in the X direction.
This is one more than the largest allowable X coordinate.
Definition at line 220 of file pnmImageHeader.I.
Referenced by PNMImage::copy_header_from(), down_to_power_2(), Texture::read(), WindowFramework::set_background_type(), PNMImage::set_color_type(), and PNMImage::write().

int PNMImageHeader::get_y_size ( ) const [inline]

Returns the number of pixels in the Y direction.
This is one more than the largest allowable Y coordinate.
Definition at line 237 of file pnmImageHeader.I.
Referenced by PNMImage::copy_header_from(), down_to_power_2(), Texture::read(), WindowFramework::set_background_type(), PNMImage::set_color_type(), and PNMImage::write().

bool PNMImageHeader::has_alpha ( ) const [inline]

Returns true if the image includes an alpha channel, false otherwise.
Unlike is_grayscale(), if this returns false it is an error to call any of the functions accessing the alpha channel.
Definition at line 184 of file pnmImageHeader.I.
References _type, INLINE, and NULL.
Referenced by PNMImage::copy_from(), PNMImage::set_color_type(), and PNMImage::write().

bool PNMImageHeader::has_alpha ( PNMImageHeader::ColorType color_type ) [inline, static]

This static variant of has_alpha() returns true if the indicated image type includes an alpha channel, false otherwise.

Definition at line 165 of file pnmImageHeader.I.
References _x_size, and INLINE.
Referenced by filter_image(), and WindowFramework::set_background_type().

bool PNMImageHeader::has_type ( ) const [inline]

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

Definition at line 252 of file pnmImageHeader.I.

bool PNMImageHeader::is_grayscale ( ) const [inline]

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.
(The gray color is actually stored in the blue channel, and the red and green channels are ignored.)
Definition at line 148 of file pnmImageHeader.I.
References _maxval, INLINE, and xelval.
Referenced by get_num_channels(), PNMImage::set_color_type(), PNMImage::write(), PNMFileTypeTGA::Writer::Writer(), and PNMFileTypeAlias::Writer::Writer().

bool PNMImageHeader::is_grayscale ( PNMImageHeader::ColorType color_type ) [inline, static]

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

Definition at line 127 of file pnmImageHeader.I.
References CT_four_channel, CT_two_channel, and INLINE.
Referenced by filter_image().

PNMReader * PNMImageHeader::make_reader ( istream * file,

bool owns_file = true,

const Filename & filename = Filename(),

string magic_number = string(),

PNMFileType * type = NULL

) 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.
owns_file should be set true if the PNMReader is to be considered the owner of the stream pointer (in which case the stream will be deleted on completion, whether successful or not), or false if it should not delete it.
The filename parameter is optional here, since the file has already been opened; it is only used to examine the extension and attempt to guess the file type.
If magic_number is nonempty, it is assumed to represent the first few bytes that have already been read from the file. Some file types may have difficulty if this is more than two bytes.
If type is non-NULL, it is a suggestion for the file type to use.
The PNMReader should be deleted when it is no longer needed.
Definition at line 189 of file pnmImageHeader.cxx.
References _type, PNMFileType::get_name(), and NULL.

PNMReader * PNMImageHeader::make_reader ( const Filename & filename,

PNMFileType * type = NULL

) 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.
The filename "-" always stands for standard input. If type is specified, it is a suggestion for the file type to use.
The PNMReader should be deleted when it is no longer needed.
Definition at line 84 of file pnmImageHeader.cxx.

PNMWriter * PNMImageHeader::make_writer ( ostream * file,

bool owns_file = true,

const Filename & filename = Filename(),

PNMFileType * type = NULL

) 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.
owns_file should be set true if the PNMWriter is to be considered the owner of the stream pointer (in which case the stream will be deleted on completion, whether successful or not), or false if it should not delete it.
The filename parameter is optional here, since the file has already been opened; it is only used to examine the extension and attempt to guess the intended file type.
If type is non-NULL, it is a suggestion for the file type to use.
The PNMWriter should be deleted when it is no longer needed.
Definition at line 386 of file pnmImageHeader.cxx.

PNMWriter * PNMImageHeader::make_writer ( const Filename & filename,

PNMFileType * type = NULL

) 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.
The filename "-" always stands for standard output. If type is specified, it is a suggestion for the file type to use.
The PNMWriter should be deleted when it is no longer needed.
Definition at line 299 of file pnmImageHeader.cxx.
References _type, Filename::empty(), PNMFileType::get_name(), PNMFileTypeRegistry::get_ptr(), PNMFileTypeRegistry::get_type_from_extension(), PNMFileType::make_writer(), NULL, and writer().

void PNMImageHeader::operator= ( const PNMImageHeader & copy ) [inline]

Definition at line 63 of file pnmImageHeader.I.
References INLINE.
Referenced by PNMImage::copy_from(), and PNMWriter::set_x_size().

void PNMImageHeader::output ( ostream & out ) const

Definition at line 474 of file pnmImageHeader.cxx.

bool PNMImageHeader::read_header ( const Filename & filename,

PNMFileType * type = NULL

)

Opens up the image file and tries to read its header information to determine its size, number of channels, etc.
If successful, updates the header information and returns true; otherwise, returns false.
Definition at line 47 of file pnmImageHeader.cxx.
Referenced by WindowFramework::set_background_type().

bool PNMImageHeader::read_magic_number ( istream * file,

string & magic_number,

int num_bytes

) [static]

Ensures that the first n bytes of the file are read into magic_number.
If magic_number is initially nonempty, assumes these represent the first few bytes already extracted. Returns true if successful, false if an end of file or error occurred before num_bytes could be read.
Definition at line 454 of file pnmImageHeader.cxx.

void PNMImageHeader::set_type ( PNMFileType * type ) [inline]

Sets the file type of this PNMImage.
This will be the default type used when an image is read, if the type cannot be determined by magic number or inferred by extension, or the type used when the image is written, if the type cannot be inferred from the filename extension.
Definition at line 292 of file pnmImageHeader.I.