photo man page on Slackware

Man page or keyword search:  
man Server   14563 pages
apropos Keyword Search (all sections)
Output format
Slackware logo
[printable version]

photo(n)		     Tk Built-In Commands		      photo(n)

______________________________________________________________________________

NAME
       photo - Full-color images

SYNOPSIS
       image create photo ?name? ?options?

       imageName blank
       imageName cget option
       imageName configure ?option? ?value option value ...?
       imageName copy sourceImage ?option value(s) ...?
       imageName data ?option value(s) ...?
       imageName get x y
       imageName put data ?option value(s) ...?
       imageName read filename ?option value(s) ...?
       imageName redither
       imageName transparency subcommand ?arg arg ...?
       imageName write filename ?option value(s) ...?
_________________________________________________________________

DESCRIPTION
       A  photo is an image whose pixels can display any color or be transpar‐
       ent.  A photo image is stored internally in full	 color	(32  bits  per
       pixel),	and is displayed using dithering if necessary.	Image data for
       a photo image can be obtained from a file or a string,  or  it  can  be
       supplied	 from C code through a procedural interface.  At present, only │
       PNG, GIF and PPM/PGM formats are supported, but an interface exists  to
       allow  additional image file formats to be added easily.	 A photo image
       is transparent in regions where no image	 data  has  been  supplied  or
       where it has been set transparent by the transparency set subcommand.

CREATING PHOTOS
       Like  all  images,  photos  are created using the image create command.
       Photos support the following options:

       -data string
	      Specifies the contents of the image as  a	 string.   The	string
	      should  contain binary data or, for some formats, base64-encoded
	      data (this is currently guaranteed to be supported for  PNG  and
	      GIF  images).  The format of the string must be one of those for
	      which there is an image file format  handler  that  will	accept
	      string data.  If both the -data and -file options are specified,
	      the -file option takes precedence.

       -format format-name
	      Specifies the name of the file format  for  the  data  specified
	      with the -data or -file option.

       -file name
	      name  gives the name of a file that is to be read to supply data
	      for the photo image.  The file format must be one of  those  for
	      which there is an image file format handler that can read data.

       -gamma value
	      Specifies that the colors allocated for displaying this image in
	      a window should be corrected for a non-linear display  with  the
	      specified gamma exponent value.  (The intensity produced by most
	      CRT displays is a power function of the input value, to  a  good
	      approximation; gamma is the exponent and is typically around 2).
	      The value specified must be  greater  than  zero.	  The  default
	      value  is	 one (no correction).  In general, values greater than
	      one will make the image lighter, and values less than  one  will
	      make it darker.

       -height number
	      Specifies	 the  height  of the image, in pixels.	This option is
	      useful primarily in situations where the user wishes to build up
	      the  contents of the image piece by piece.  A value of zero (the
	      default) allows the image to expand or shrink vertically to  fit
	      the data stored in it.

       -palette palette-spec
	      Specifies	 the  resolution of the color cube to be allocated for
	      displaying this image, and thus the number of colors  used  from
	      the  colormaps  of  the windows where it is displayed.  The pal‐
	      ette-spec string may be either a single decimal number, specify‐
	      ing  the	number of shades of gray to use, or three decimal num‐
	      bers separated by slashes (/), specifying the number  of	shades
	      of  red, green and blue to use, respectively.  If the first form
	      (a single number) is used, the image will be displayed in	 mono‐
	      chrome (i.e., grayscale).

       -width number
	      Specifies	 the  width of the image, in pixels.	This option is
	      useful primarily in situations where the user wishes to build up
	      the  contents of the image piece by piece.  A value of zero (the
	      default) allows the image to expand or  shrink  horizontally  to
	      fit the data stored in it.

IMAGE COMMAND
       When a photo image is created, Tk also creates a new command whose name
       is the same as the image.  This command may be used to  invoke  various
       operations on the image.	 It has the following general form:
	      imageName option ?arg arg ...?
       Option and the args determine the exact behavior of the command.

       Those options that write data to the image generally expand the size of
       the image, if necessary, to accommodate the data written to the	image,
       unless  the  user  has  specified non-zero values for the -width and/or
       -height configuration options, in which case the width  and/or  height,
       respectively, of the image will not be changed.

       The following commands are possible for photo images:

       imageName blank
	      Blank  the image; that is, set the entire image to have no data,
	      so it will be displayed as transparent, and  the	background  of
	      whatever window it is displayed in will show through.

       imageName cget option
	      Returns  the  current value of the configuration option given by
	      option.  Option may have any of the values accepted by the image
	      create photo command.

       imageName configure ?option? ?value option value ...?
	      Query  or modify the configuration options for the image.	 If no
	      option is specified, returns a list describing all of the avail‐
	      able options for imageName (see Tk_ConfigureInfo for information
	      on the format of this list).  If option  is  specified  with  no
	      value,  then the command returns a list describing the one named
	      option (this list will be identical to the corresponding sublist
	      of  the  value  returned	if no option is specified).  If one or
	      more option-value pairs are specified, then the command modifies
	      the  given  option(s)  to have the given value(s);  in this case
	      the command returns an empty string.  Option may have any of the
	      values accepted by the image create photo command.

       imageName copy sourceImage ?option value(s) ...?
	      Copies a region from the image called sourceImage (which must be
	      a photo image) to the  image  called  imageName,	possibly  with
	      pixel  zooming and/or subsampling.  If no options are specified,
	      this command copies the whole  of	 sourceImage  into  imageName,
	      starting	at  coordinates	 (0,0)	in  imageName.	 The following
	      options may be specified:

	      -from x1 y1 x2 y2
		     Specifies a rectangular sub-region of the source image to
		     be	 copied.  (x1,y1) and (x2,y2) specify diagonally oppo‐
		     site corners of the rectangle.  If	 x2  and  y2  are  not
		     specified,	 the  default value is the bottom-right corner
		     of the source image.  The pixels copied will include  the
		     left and top edges of the specified rectangle but not the
		     bottom or right edges.  If the -from option is not given,
		     the default is the whole source image.

	      -to x1 y1 x2 y2
		     Specifies	a  rectangular	sub-region  of the destination
		     image to be affected.  (x1,y1) and (x2,y2) specify diago‐
		     nally  opposite  corners  of the rectangle.  If x2 and y2
		     are not specified, the default value is (x1,y1) plus  the
		     size of the source region (after subsampling and zooming,
		     if specified).  If x2 and y2 are  specified,  the	source
		     region will be replicated if necessary to fill the desti‐
		     nation region in a tiled fashion.

	      -shrink
		     Specifies that the size of the destination	 image	should
		     be reduced, if necessary, so that the region being copied
		     into is at the bottom-right corner of  the	 image.	  This
		     option  will  not affect the width or height of the image
		     if the user has specified a non-zero value for the -width
		     or -height configuration option, respectively.

	      -zoom x y
		     Specifies that the source region should be magnified by a
		     factor of x in the X direction and y in the Y  direction.
		     If	 y  is	not given, the default value is the same as x.
		     With this option, each pixel in the source image will  be
		     expanded  into a block of x x y pixels in the destination
		     image, all the same color.	 x and y must be greater  than
		     0.

	      -subsample x y
		     Specifies that the source image should be reduced in size
		     by using only every xth pixel in the X direction and  yth
		     pixel in the Y direction.	Negative values will cause the
		     image to be flipped about the Y or X axes,	 respectively.
		     If y is not given, the default value is the same as x.

	      -compositingrule rule
		     Specifies	how transparent pixels in the source image are
		     combined with the destination image.  When a  compositing
		     rule  of overlay is set, the old contents of the destina‐
		     tion image are visible,  as  if  the  source  image  were
		     printed  on  a  piece of transparent film and placed over
		     the top of the destination.  When a compositing  rule  of
		     set is set, the old contents of the destination image are
		     discarded and  the	 source	 image	is  used  as-is.   The
		     default compositing rule is overlay.

       imageName data ?option value(s) ...?
	      Returns  image  data  in	the  form  of  a string. The following
	      options may be specified:

	      -background color
		     If the color is specified, the data will not contain  any
		     transparency  information.	 In all transparent pixels the
		     color will be replaced by the specified color.

	      -format format-name
		     Specifies the name of the image file format handler to be
		     used.   Specifically,  this  subcommand  searches for the
		     first handler whose name matches an initial substring  of
		     format-name  and  which  has  the	capability  to write a
		     string containing this image data.	 If this option is not
		     given,  this  subcommand uses a format that consists of a
		     list (one element per row)	 of  lists  (one  element  per
		     pixel/column)  of colors in “#rrggbb” format (where rr is
		     a pair of hexadecimal digits for the red channel, gg  for
		     green, and bb for blue).

	      -from x1 y1 x2 y2
		     Specifies	 a  rectangular	 region	 of  imageName	to  be
		     returned.	If only x1 and y1 are  specified,  the	region
		     extends from (x1,y1) to the bottom-right corner of image‐
		     Name.  If all four coordinates are	 given,	 they  specify
		     diagonally	 opposite  corners  of the rectangular region,
		     including x1,y1 and excluding  x2,y2.   The  default,  if
		     this option is not given, is the whole image.

	      -grayscale
		     If	 this  options is specified, the data will not contain
		     color information. All pixel  data	 will  be  transformed
		     into grayscale.

       imageName get x y
	      Returns the color of the pixel at coordinates (x,y) in the image
	      as a list of three integers between 0 and 255, representing  the
	      red, green and blue components respectively.

       imageName put data ?option value(s) ...?
	      Sets  pixels  in	imageName to the data specified in data.  This
	      command first searches the list of image	file  format  handlers
	      for  a  handler  that  can  interpret the data in data, and then
	      reads the image encoded within into imageName  (the  destination
	      image).	If data does not match any known format, an attempt to
	      interpret it as a (top-to-bottom) list of	 scan-lines  is	 made,
	      with each scan-line being a (left-to-right) list of pixel colors
	      (see Tk_GetColor for a  description  of  valid  colors.)	 Every
	      scan-line	 must be of the same length.  Note that when data is a
	      single color name, you are instructing Tk to fill a  rectangular
	      region with that color.  The following options may be specified:

	      -format format-name
		     Specifies the format of the image data in data.  Specifi‐
		     cally, only image file format handlers whose names	 begin
		     with  format-name	will  be  used	while searching for an
		     image data format handler to read the data.

	      -to x1 y1 ?x2 y2?
		     Specifies the coordinates of the top-left corner  (x1,y1)
		     of the region of imageName into which the image data will
		     be copied.	 The default position is (0,0).	 If  x2,y2  is
		     given and data is not large enough to cover the rectangle
		     specified by this option, the image data  extracted  will
		     be	 tiled	so it covers the entire destination rectangle.
		     Note that if data specifies a single color value, then  a
		     region  extending	to the bottom-right corner represented
		     by (x2,y2) will be filled with that color.

       imageName read filename ?option value(s) ...?
	      Reads image data from the file named filename  into  the	image.
	      This  command  first searches the list of image file format han‐
	      dlers for a handler that can interpret the data in filename, and
	      then reads the image in filename into imageName (the destination
	      image).  The following options may be specified:

	      -format format-name
		     Specifies the format  of  the  image  data	 in  filename.
		     Specifically, only image file format handlers whose names
		     begin with format-name will be used while	searching  for
		     an image data format handler to read the data.

	      -from x1 y1 x2 y2
		     Specifies a rectangular sub-region of the image file data
		     to be copied to the destination image.  If only x1 and y1
		     are  specified,  the  region  extends from (x1,y1) to the
		     bottom-right corner of the image in the image  file.   If
		     all  four	coordinates are specified, they specify diago‐
		     nally opposite corners or the region.   The  default,  if
		     this  option  is not specified, is the whole of the image
		     in the image file.

	      -shrink
		     If this option, the size of imageName will be reduced, if
		     necessary,	 so  that the region into which the image file
		     data are read is at the bottom-right corner of the image‐
		     Name.  This option will not affect the width or height of
		     the image if the user has specified a non-zero value  for
		     the -width or -height configuration option, respectively.

	      -to x y
		     Specifies	the  coordinates of the top-left corner of the
		     region of imageName into which data from filename are  to
		     be read.  The default is (0,0).

       imageName redither
	      The  dithering  algorithm used in displaying photo images propa‐
	      gates quantization errors from one pixel to its  neighbors.   If
	      the image data for imageName is supplied in pieces, the dithered
	      image may not be exactly correct.	 Normally  the	difference  is
	      not noticeable, but if it is a problem, this command can be used
	      to recalculate the dithered image in each window where the image
	      is displayed.

       imageName transparency subcommand ?arg arg ...?
	      Allows examination and manipulation of the transparency informa‐
	      tion in the photo image.	Several subcommands are available:

	      imageName transparency get x y
		     Returns a boolean indicating if the  pixel	 at  (x,y)  is
		     transparent.

	      imageName transparency set x y boolean
		     Makes  the pixel at (x,y) transparent if boolean is true,
		     and makes that pixel opaque otherwise.

       imageName write filename ?option value(s) ...?
	      Writes image data from imageName to a file named filename.   The
	      following options may be specified:

	      -background color
		     If	 the color is specified, the data will not contain any
		     transparency information. In all transparent  pixels  the
		     color will be replaced by the specified color.

	      -format format-name
		     Specifies the name of the image file format handler to be
		     used to write the data to the file.   Specifically,  this
		     subcommand	 searches  for	the  first  handler whose name
		     matches an initial substring of format-name and which has
		     the capability to write an image file.  If this option is
		     not given, the format is guessed from the file extension.
		     If	 that  cannot  be determined, this subcommand uses the
		     first handler that has the capability to write  an	 image
		     file.

	      -from x1 y1 x2 y2
		     Specifies a rectangular region of imageName to be written
		     to the image file.	 If only x1 and y1 are specified,  the
		     region extends from (x1,y1) to the bottom-right corner of
		     imageName.	 If all four coordinates are given, they spec‐
		     ify   diagonally  opposite	 corners  of  the  rectangular
		     region.  The default, if this option is not given, is the
		     whole image.

	      -grayscale
		     If	 this  options is specified, the data will not contain
		     color information. All pixel  data	 will  be  transformed
		     into grayscale.

IMAGE FORMATS
       The  photo  image  code	is structured to allow handlers for additional
       image file formats to be added easily.  The photo image code  maintains
       a  list of these handlers.  Handlers are added to the list by register‐
       ing them with a call to	Tk_CreatePhotoImageFormat.   The  standard  Tk
       distribution  comes  with  handlers  for	 PPM/PGM, PNG and GIF formats,
       which are automatically registered on initialization.

       When reading an image file or processing string data specified with the
       -data  configuration  option, the photo image code invokes each handler
       in turn until one is found that claims to be able to read the  data  in
       the file or string.  Usually this will find the correct handler, but if
       it does not, the user may give a format name with the -format option to
       specify	which  handler	to use.	 In fact the photo image code will try
       those handlers whose names begin with  the  string  specified  for  the
       -format	option	(the comparison is case-insensitive).  For example, if
       the user specifies -format gif, then a handler named GIF87 or GIF89 may
       be  invoked,  but a handler named JPEG may not (assuming that such han‐
       dlers had been registered).

       When writing image data to a file, the processing of the -format option
       is  slightly  different:	 the string value given for the -format option
       must begin with the complete name of the	 requested  handler,  and  may
       contain	additional  information	 following that, which the handler can
       use, for example, to specify which variant to use of the	 formats  sup‐
       ported  by  the	handler.  Note that not all image handlers may support
       writing transparency data to a file, even where the target image format
       does.

   FORMAT SUBOPTIONS
       Some image formats support sub-options, which are specified at the time │
       that the image is loaded using additional words in the -format  option. │
       At the time of writing, the following are supported:		       │

       gif -index indexValue						       │
	      When  parsing  a multi-part GIF image, Tk normally only accesses │
	      the first image. By giving the  -index  sub-option,  the	index‐ │
	      Value'th	value  may  be used instead. The indexValue must be an │
	      integer from 0 up to the number of image parts in the GIF data.  │

       png -alpha alphaValue						       │
	      An additional alpha  filtering  for  the	overall	 image,	 which │
	      allows  the  background  on which the image is displayed to show │
	      through. This usually also has the effect	 of  desaturating  the │
	      image. The alphaValue must be between 0.0 and 1.0.

COLOR ALLOCATION
       When a photo image is displayed in a window, the photo image code allo‐
       cates colors to use to display the image and dithers the image, if nec‐
       essary,	to  display  a reasonable approximation to the image using the
       colors that are available.  The colors are allocated as a  color	 cube,
       that is, the number of colors allocated is the product of the number of
       shades of red, green and blue.

       Normally, the number of colors allocated is chosen based on  the	 depth
       of  the window.	For example, in an 8-bit PseudoColor window, the photo
       image code will attempt to allocate seven shades of red,	 seven	shades
       of  green  and  four  shades  of blue, for a total of 198 colors.  In a
       1-bit StaticGray (monochrome) window,  it  will	allocate  two  colors,
       black  and white.  In a 24-bit DirectColor or TrueColor window, it will
       allocate 256 shades each of red, green and blue.	 Fortunately,  because
       of  the	way that pixel values can be combined in DirectColor and True‐
       Color windows, this only requires 256 colors to be allocated.   If  not
       all  of	the  colors can be allocated, the photo image code reduces the
       number of shades of each primary color and tries again.

       The user can exercise some control over the number  of  colors  that  a
       photo  image  uses  with	 the  -palette	configuration option.  If this
       option is used, it specifies the maximum number of shades of each  pri‐
       mary  color to try to allocate.	It can also be used to force the image
       to be displayed in shades of gray, even on a color display, by giving a
       single number rather than three numbers separated by slashes.

CREDITS
       The  photo  image  type was designed and implemented by Paul Mackerras,
       based on his earlier  photo  widget  and	 some  suggestions  from  John
       Ousterhout.

EXAMPLE
       Load an image from a file and tile it to the size of a window, which is
       useful for producing a tiled background:

	      # These lines should be called once
	      image create photo untiled -file "theFile.ppm"
	      image create photo tiled

	      # These lines should be called whenever .someWidget changes
	      # size; a <Configure> binding is useful here
	      set width	 [winfo width .someWidget]
	      set height [winfo height .someWidget]
	      tiled copy untiled -to 0 0 $width $height -shrink

       The PNG image loader allows the application of an additional alpha fac‐ │
       tor  during loading, which is useful for generating images suitable for │
       disabled buttons:						       │

	      image create photo icon -file "icon.png"			       │
	      image create photo iconDisabled -file "icon.png" \	       │
		      -format "png -alpha 0.5"				       │
	      button .b -image icon -disabledimage iconDisabled		       │

SEE ALSO
       image(n)

KEYWORDS
       photo, image, color

Tk				      4.0			      photo(n)
[top]
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
More information is available in HTML format for server Slackware

List of man pages available for Slackware

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net