Re: [TCLCORE] TIP 714: image driver photo formats

[Harald O. <har...@el...>]

Dear Tk team,

thanks for the feed-back by Ashok, Paul and Emiliano.
There are no comments rejecting this TIP.

TIP 714 is now updated.

I understand that the name of the new subcommand is not optimal.
The TIP contains all current proposals.

In addition, the TIP contains a drafted specification of the 
capabilities subcommand.
Any opinions welcome, if this makes sense or may just be removed.
The returned list item names are not beautiful neither.
Please comment and I will change the specification.

I have thought two days on the proposal by Emiliano.
Thanks for the pointer to BLT's "picture" image type handler.
This is awesome work.
It may also be possible that this type may by enhanced by this TIP like 
configuring default values or querying option lists like dither methods, 
which may be used in selection boxes later on.

I think, more generic options may later be created on the script level.
For example, a formats method for all image types:

set formats {}
foreach type [image types] {
     if {![catch {image handler $type formats} myFormats]} {
         lappend formats {*}$myFormats
     }
}

Or a photo ensemble, which returns the capabilities:
proc photo {option format} {
     switch -exact $option {
         writesupported {
             return [expr {"write" in [image handler photo capabilities]}]
         }
     }
}

As modifying a C structure is expensive, I like most general interfaces 
on the C level. Any specific function may then be added on the script level.

And of cause, I am not insisting in implementing or proposing this.
I started it, as I see the usage and I already know the code a bit due 
to the metadata extension. Any opinion "stop now, this is useless" is 
welcome!

Thanks for all,
Harald