Re: Questions about event handling with Ttk::treeview

Hello Steve,

have a look at the demo of the treeview. You can find it in the
directory <Tcl-Install-Dir>\Demo\widget.tcl and then under the topic
Listboxes and Trees->A Directory Tree browser. On unix-like systems
you can find it in /usr/local/share I think.

It shows the event binding. For your checkboxes I am not sure if it is
possible. You can use tags to assign images, but checkboxes ??? The
extension TkTreeCtrl has examples for this kind, or if you want to
stay with Tcl 8.4 you can use the BLT package that also supports this.


On 27 Apr., 06:03, Steve <f...@xxxxxxxxxxx> wrote:
Pardon the newbie-level from which I ask this question.  I used Tcl/Tk
pretty extensively back in the 90's, but am YEARS out of practice.  I
got excited after reading about the advances in the Tk toolkit over the
past few years, and have been playing around trying to ramp back up...

I'm trying to write a small Tcl/Tk app with a treeview widget for
selecting multiple files and directories in the filesystem.  I'm needing
to implement the following behavior with the widget:

1) When a directory is selected, it causes all the files and
subdirectories beneath that directory to be selected also.

2) Selecting another item, even without holding down the Shift or Ctrl
key, does NOT deselect the currently item(s).  Once a file or directory
has been selected, it is only deselected if explicitly clicked a second
time (or maybe if its parent is deselected).

Some other GUI toolkits have a "checkbox tree" kind of widget that
behaves this way (typically with a checkbox to the left of each item for
selecting).  I'm gathering that Ttk::treeview doesn't exactly offer this
out-of-the-box (if I'm wrong please stop me at this point so I save
time!).  However, maybe I can roll my own functionality through event
handling?  That is, I can keep track of the currently selected items in
a variable... and when the tree is clicked, I can process what the
currently selected items SHOULD be based on what was clicked.

The problem is that I'm having a hard time grasping the event handling
model for the treeview widget.  Items of confusion (so far):

1) The treeview man page
(http://www.tcl.tk/man/tcl8.5/TkCmd/ttk_treeview.htm) talks about the
relevant events being <KeyPress> or <ButtonPress>.  However, the TkDocs
tutorial site (http://www.tkdocs.com/tutorial/tree.html) references
<TreeviewSelect>.  I'm not sure what event I'm looking for.

2) I'm also not sure how to get the event.  The Event Handling page on
that TkDocs site (http://www.tkdocs.com/tutorial/concepts.html#events)
talks about using the "bind" command.  However, the bottom of treeview
page on that site (http://www.tkdocs.com/tutorial/tree.html) talks about
using the "tag bind" command off the treeview object itself.  The
example given is a little too bare-bones for my intellect, unfortunately.

3) Finally, even once I DO capture the event I'm not sure what to do
with it.  The "treeview selection" command returns a list of the
currently selected items, but I'm not sure how to translate that into a
tree structure so my code can process it correctly (i.e. recognizing
that a directory has been selected and therefore all the children should
be selected as well).  I suppose the brute force approach would be to
start with my own data structure representing the filesystem tree, and
write functions that can export the initial tree as well as a list of
id's to later pass to "treeview selection set".  If anyone has an idea
for a more elegant approach I would love to hear it!

Anyway, if you've read this far then thanks alot.  I realize this post
is a mouthful of a question, and I don't really need someone to write
the app for me.  However, if you can point me in the right direction on
any of these sub-questions raised I would deeply appreciate it.  Thanks!

.