DOKK / manpages / debian 11 / libtk-img-doc / img-png.3tk.en
img-png(3tk) Img img-png(3tk) 







img-png - Img, Portable Network Graphics format (png)








package require Tk 


package require img::png ?1.4?


image create photo ?name?
  ?options?












The package img::png is a sub-package of Img. It can
    be loaded as a part of the complete Img support, via package require
    Img, or on its own, via package require img::png.


Like all packages of Img it does not provide new
    commands, but extends the existing Tk command image so that it
    supports files containing raster images in the Portable Network Graphics
    format (png). More specifically img::png extends Tk's
    photo image type.


The name of the new format handler is png. This handler
    provides new additional configuration options. See section PNG
    OPTIONS for more detailed explanations.


All of the above means that in a call like



  

  





  
[1]

  
Image data in png format (options -data and -file) is
      detected automatically.

  
[2]

  
The format name png is recognized by the option -format. In
      addition the value for the option is treated as list and may contain any
      of the special options listed in section PNG OPTIONS.










The handler provides the following options:



  

  
This option is supported for reading only.
    
If set to true, additional information about the file
        format is printed to stdout. Default is false.

  

  

  
This option is supported for reading only.
    
Use the specified gamma value when reading an image. This
        option overwrites gamma values specified in the file. If this option is
        not specified and no gamma value is in the file, a default value of 1.0
        is used.

  

  

  
This option is supported for reading only.
    
If set to false, a matte (alpha) channel is ignored
        during reading or writing. Default is true.

  

  

  
This option is supported for reading only.
    
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. Specifying an alpha value,
        overrides the setting of the matte flag, i.e. reading a file which has
        no alpha channel (Greyscale, RGB) will add an alpha channel to the image
        independent of the matte flag setting.

  




The handler provides no true write options at all, but accepts
    pairs of keys and values when writing a PNG file. Each pair will be written
    as a named text chunk where the key provides the name of the chunk and the
    value its contents. For example






    png Author <name> Title <title> Description ...











If you want to write images to disk which contain transparency
    information (e.g. PNG with alpha channel) you need at least Tk
  8.3.








img-bmp, img-dted, img-gif, img-ico, img-intro, img-jpeg, img-pcx,
    img-pixmap, img-png, img-ppm, img-ps, img-raw, img-sgi, img-sun, img-tga,
    img-tiff, img-window, img-xbm, img-xpm








image handling, png, tk








Copyright (c) 1995-2009 Jan Nijtmans <nijtmans@users.sourceforge.net>








  

    1.4
    img-png