diff options
Diffstat (limited to 'tkimg/doc/img-png.man')
-rw-r--r-- | tkimg/doc/img-png.man | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/tkimg/doc/img-png.man b/tkimg/doc/img-png.man new file mode 100644 index 0000000..1acf491 --- /dev/null +++ b/tkimg/doc/img-png.man @@ -0,0 +1,73 @@ +[comment {-*- tcl -*- doctools}] +[vset FORMATNAME png] +[vset FORMATFULLNAME {Portable Network Graphics format}] + +[include format-header.inc] + +This handler provides new additional configuration options. See +section [sectref {PNG OPTIONS}] for more detailed explanations. + + +[include format-middle.inc] + + +In addition the value for the option is treated as list and may +contain any of the special options listed in section + +[sectref {PNG OPTIONS}]. + +[list_end] + + + +[section {PNG OPTIONS}] + +The handler provides the following options: + +[list_begin definitions] + +[lst_item "[option -matte] [arg bool]"] + +This option is supported for reading only. +[nl] +If set to [const false], a matte (alpha) channel is ignored +during reading or writing. Default is [const true]. + + +[lst_item "[option -alpha] [arg float]"] + +This option is supported for reading only. +[nl] +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. + +[list_end] + +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 + +[example { + png Author <name> Title <title> Description ... +}] + + +[section TRANSPARENCY] + +If you want to write images to disk which contain transparency +information (e.g. PNG with alpha channel) you need at least + +[package Tk] 8.3. + + + +[list_begin definitions] +[include format-footer.inc] |