Hi David: What you are looking at in that little sub is called a recursive
routine.
A recursive routine will call itself if a specified condition is met.
They are very useful for processing anything that uses nodes like a TreeView or
xml document or even a form menu.
I wont get into much more since I havent done much with vbs and dont want to
confuse you but if you do a little introductory reading about recursive
routines you will see how powerful they can be.
As for your tree view, 9 levels is way too many if you are going to use it for
real.
It requires too much guessing and expanding and collapsing and liniar
navigation compared to other solutions to handle that many choices.
It also will be a pain to work with that many levels if just learning.
Anyway, I'll begg of for nnow since vb.net TreeViews may have diferent methods
and properties although they sound pretty much the same.
600 lines of code is a whole lot of code to muck with a TreeView but when you
start working with indexes and check boxes I guess it could get that large.
Rick USA
----- Original Message -----
From: David
To: [email protected]
Sent: Thursday, April 11, 2013 9:12 PM
Subject: Re: Treeview Questions - Still attempting to learn :)
Yes, Bruce.
I do follow you somehow here. If you have a simple tree, holding three
levels, with a maximum of 10 entries on each level, you could do your kind of
math. The number 175, then would indicate, we are to follow the first branch
from the root, the seventh branch of the next level, and finally, get hold of
the fifth leaf (or item) on the third level.
Now, if we imagined that the three items here in question, had the respective
names of "Grocery", "Lunch meat", and "Ham". Allright, you could follow
numbers, calculated from the Data field, and I do see that could be easy. But
you also could run through the levels, and follow the text strings: Grocery,
lunch meat, Ham. Again, this will take, that there never occurs same text, on
more than one item.
But another issue, that comes from your Data field math, is this. Now,
imagine that you have five levels, and you reserve enough space in your
calculation for having one hundred entries as a max on each level. You then
would have the numbers: 10, 89, 22,11,75; which you would have to put together
for an entry in the Data field. It all would come out, as the tremmendous
number of: 1089221175. Still, the number would fit inside the maximum of a
LongValued number. But hang on, we are going to elaborate just a bit more. As I
told, my tree will at the max have ten levels. If now, we are to reserve space
in our calculation of the Data field, for a maximum of one hundred entries on
each level, you would end up with a 20 digit number for the Data field. This
will (I guess), by far exceed the limits of any handled numbers on the
computer. As such, I guess the Data field will no longer have any benefit, as I
would have to store it as a String, and perform a split of that string into
separate two-digit numbers, for refering to the branch of each level to follow.
My big issue here, is if all that calculation and splitting of numbers,
actually will result in just as much coding and computer resources, as would
the tracing of the Text field that matches a specified criteria. Hope this all
made sense. I am not telling the one approach to be superior to the other, only
was wondering if there was any direct features for the Data field build in with
the treeview object, that would not be available on the Text field. I.e, it
would have been nice, if you could have entered one instruction, passing the
Data field to the object, and it would have returned the full Tree-lim, if you
know what I mean. But my guess is, there is none such feature, and so the one
approach might do fine - and the other will do just as well. OK, one might be
more in line with high-tech and professional ways of handling the matter, the
other might be a bit more homemade. :) At least, that is what I get from it
all, at this point.
Again, if you have other stuff, which you need to compare with a selection
from the treestructure, I can see it might be nice with a number retrieved in
the background from the Data field - which you in turn could use for looking up
things in a database or a dictionary. I just wonder, how you would approach a
twenty digit number in the Data field. My guess is, that you would have an
error thrown at you, if you tried to assign such a number to the Data field.
Nope, I haven't tried, but was just making a guess here.
Still, thank you for trying to clarify, and I do appreciate any further
feedback.
----- Original Message -----
From: BX
To: [email protected]
Sent: Friday, April 12, 2013 1:49 AM
Subject: Re: Treeview Questions - Still attempting to learn :)
Hi David,
The text in the tree view is the stuff you see being said on the tree.
The data, is the ID tag for that item selected.
Now, when you go down another level, you deciding the data to reflect
the level.
Suppose you have on the main list 10 items, OK?
Then on the second level you have no more than 10 items, OK?
The the third level you also have 10 items, OK?
Now you are dealing with powers of 10, or 0 to 9. So, you have 3 levels
so each ID tag of each level would be a power of 10, or if your selected item
is 19, OK?
Then you are item 1 of the first level and the 9'th, actually 10'th
item of the second level, OK?
This is how you set your check box, which does not exist, but the tree
view, or limb you follow is the value of the data item at that point.
This is what I had sent you and yes, what I sent you is confusing, but
the guts of that is the beginning of the MainProc where I start doing that
level check; but you have to understand my program to get there.
so, as I have mentioned above, set your data value to show the full
amount of data, checks at the tree view level you are opened up to.
In this case you only have one item selected at each level and that is
all you can do in a tree view, but since you are selecting a sub value of a
main level, you do not need anything more than that. For that is the meaning of
a tree view, following a tree limb...
I hope this helps. I will send or post the tree view items and how to
make them, there are only 2 or 3 places where that happen, one place where the
main menu is made into categories, then the listing of file names or
programming names in the second level, and the third level is the info supplied
for each program. This is what I did in the UnInstall program.
So, the text is what is displayed and said when you move through the
tree view, the data is the ID tag for each and every item on the tree and you
make up the rules for that.
As I said, using the power of 10 only allows 10 items for each sub
level. You can expand that as I did to indicate up to a 1000 at each level
which means you are going down each level as a power of 3 each. You can make it
even large, each call to the subroutine must reflect that choice.
But ID tags can be words as well if you choose to do so...
I hope this helps, next I will send the exact 2 programs that do this
for you, along with the controlling top level loop...
Sincerely
Bruce A. Babcock
Sent: Thursday, April 11, 2013 7:18 PM
Subject: Re: Treeview Questions - Still attempting to learn :)
As regards to my prior message, I have solved issue number 3, how to
quickly iterate
the whole tree-structure. Still, my other questions remain open.
But for what it is worth, and to all who might benefit from a quick way
of running
through all the possible items on a tree, here I am pasting in the sub
routine, that
will do the whole iteration. It is not more than a few lines of coding,
and will
do with any number of branches and leaves, from what I can see. In the
pasted example,
the actual line of interest, is the Speak line, which will read out the
Text property
of the individual item. You can replace this line, with any other
activity you want
performed on the individual item. The sub will take a TreeviewItems
object, as its
parameter. If you want the whole treeview iterated, from root and out,
you could
simply do something like:
IterateTree TreeviewObject.TopLevel
Where TreeviewObject is an object pointing to a treeview, that you have
defined.
In my testing app, I called it from the DialogEventHandler function of my
testing
dialog. Here I have defined a treview control, named TV_Test, and the sub
is called
when a button "BTN_SpeakTree) is pressed. The snip-it of the
DialogEventHandler then
looks like this:
Case "BTN_SpeakTree"
If DEvent = ButtonClicked Then
IterateTree DObj.Control( "TV_Test" ).TopLevel
DialogEventHandler = True
Exit Function
End If 'BTN_SpeakTree.
And, here is the iteration sub:
Sub IterateTree( TVItems)
Dim CurrentItem: Set CurrentItem = Nothing
Dim ItemNumber
For ItemNumber = 1 To TVItems.Count
Set CurrentItem = TVItems.Item( ItemNumber)
' The following line, is the actual action, performed on the individual
item. Replace
it with whatever you want:
Speak CurrentItem.Text &","
If CurrentItem.Children.Count >=1 Then
IterateTree CurrentItem.Children
Set currentItem = Nothing
End If 'CurrentItem.Children.Count >=1.
Next 'ItemNumber.
' Room Cleaning:
If Not CurrentItem Is Nothing Then Set CurrentItem = Nothing
If Not TVItems Is Nothing Then Set TVItems = Nothing
End Sub 'IterateTree.
Hope all of this will be of any help for the rest of the community. I am
sure, things
can be modified to work even more smoothly, and that you can change
whatever part
of it, to fit your personal scripting needs. But at least, I wanted to
share this,
since it is not something that first comes to mind, how to handle. Enjoy
it. And
if anyone has any feedback on the other issues I presented in the initial
message
of mine, I am all greatful for whatever feedback you may have.
Thanks again,
----- Original Message -----
From:
David
To:
[email protected]
Sent: Thursday, April 11, 2013 11:14 PM
Subject: Treeview Questions - Still attempting to learn :)
I am still trying to wrap my brain around the complexity of a treeview,
and how to
gain the fullest benefit from this kind of control. Earlier, when asking,
one of
you send me a code snip-it from one of his apps, holding some 600 lines.
Thanks to
you, and it got me somehow going. Yet, I don't follow all of your
thinking, or the
reason why you do this and that. That is one of the drawbacks of 600
lines of coding.
Smile.
Allright, I have got that far, that I am able to fill in the information
on the tree,
and get it displayed in my dialog. So far, this works satisfactory. Now,
I am stuck
with a few challenges, most of all when comes to retrieve the needed
information
from the treeview. I have a feeling, most of my getting stuck here, is
due to a lack
of understanding. That's why, I hoped to have some clarification on the
following
questions.
1. What is the exact benefit of the Text, as compared to the Data, field
in a treeview
item. OK, I do get the fact, that in case the same text could happen to
be on several
branches or leaves of the tree, the Data field could be used to
distinguish the one
occurrance from the other. But if i have a tree, where no text will
appear more than
once, is there any reason why I should bother about filling in the data
field for
each item? I.e, would there be any search feature or the like, that could
be quicker
done by iterating the tree-structure on the Data fields, compared to
simply just
concentrating on the Text fields.
2. The treeview I am building, has checkboxes, which the user can check
for each
item on the tree. I have searched the Reference manual, but not sure if I
have overlooked
anything. From what I can see, there is no way in determining whether a
treeview
Item has been checked or not. I see the Selected feature, but from what
my testing
leads me to understand, this simply let's me know when an item has focus
(that is,
when the cursor is placed on the item, the Selected feature will be set).
Is it correct,
that there is no build-in feature, that would "fire", when a treeview
item has been
checked or unchecked? If this is the case, technically, why? We have
features for
Checkboxes, which will tell us when it is checked and not - and we have
similar features
for a multi-selection listbox. Why would there be no feature set,
whenever a treeview
item is checked?
3. Does anyone have a simple quick iteration routine, for "rushing"
through a whole
treeview, including all its branches and leaves. My treeview, might hold
as much
as 9 sublevels, in addition to the root. And it might hold different
amounts of entries
on each branch or sublevel. I guess the best would be to use some
For...Next loops,
and somehow retrieve the Count property for each branch. But I have run
my head into
the wall, as to how to get through absolutely all the possible items on
the tree.
I guess, that is the one way to go, when iterating the different items,
or am I totally
lost in such an approach? Say for instance, the user would have been
given the chance
of searching for a given text, which would be the Text property of an
item on the
tree. I then guess, I will have to iterate all the current items on the
tree, looking
out for that particular text. And, that is why, I wondered if there was a
simple
routine, that would perform such a "run-through", with relatively few
lines of coding.
Yep, I did read through I don't know how many pages, in the Reference
manual, and
I have been looking through quite a few lines of existing coding. I am
sure, I can
get on with this, if only I can wrap myself around a few corners. So,
anyone who
has the urge to help me on getting those pieces of information
straightend out, thanks
to you, as it surely will help me crawling my way further on. :) Only
hope my questions
were clearly enough stated, that you will be able to give me the right
push. :)
