[Explain motivation (cron, possible sneer at Java, portability, ...]
LV Can someone go into the technical details of what parts of Tk require a display and what parts do not?
For instance, if one were to write a C app which created a canvas, placed things onto the canvas, configured various colors, text, etc., then commanded the canvas to create PostScript, would a display be necessary for any of this?
[Explain alternatives:
#! /usr/local/bin/tclsh8.3
puts "Content-Type: image/x-portable-graymap"
puts ""
puts "P2" ;# ASCII PGM "magic number"
puts "10 10" ;# width and height
puts "18" ;# Max grey value
for {set i 0} {$i<10} {incr i} {
set line ""
for {set j 0} {$j<10} {incr j} {
lappend line [expr {$i+$j}]
}
puts $line
}
exitA small and incomplete TGA image reader which reads a file into a format that can then later be fairly easily manipulated without the requirement of Tk. The format is compatible with one of the accepted (albeit undocumented) formats for Tk photos.
See: TGA image reader.
See also "strimj - string image routines" and "barchart". GIF has code snippets for writing image files in pure Tcl.
[Do something about Tk's "-nodisplay" ...]