Home Newsletter

Nederlandse pagina niet beschikbaarHome > Article index > Treeview control > Features

An MSForms (all VBA) treeview

Pages in this article

  1. Features
  2. How To Use
  3. Examples

Features

Performance

Realistically a VBA form with all the controls we need for each node can’t be expected to match that of the compiled original. Even so we are surprised at what has been possible, albeit with considerable tuning and refining. Light testing suggests 1000 to 2000 nodes is quite feasible even in a typical five year old laptop, depending on the configuration of the treeview.

Cosmetics

The original has a wide variety of features and functionality. We have tried to replicate most of these, and added a few features of our own.

Checkboxes

The common controls treeview has a checkboxes option so you can check nodes. We ensured our treeview has that too.

A picture says more than a thousand words, so:

Checkboxes are possible and work
Checkboxes are possible and work!

Expand/collapse boxes or icons

By default we draw a rectangle with a plus or minus characters as text to mimic the expand/collapse boxes. You can also opt for expand/collapse icons. We have bundled XP and Win7 style expander icons in the demo form or you can customize your own as you wish:

 Expander icons are provided
Icons as expand/collapse buttons

Lines

The treeview from the common controls lib always shows lines to indicate the structure. With ours it is optional to show lines. The choice might be for aesthetic reasons, however a very large treeview will load significantly faster without lines so that might be an overriding consideration.

Choose whether or not to show lines
Choose whether or not to show lines

Icons

Again, let's just look at the picture!

Icons can be added
You can add icons too!

If you are familiar with the ImageList control we have incorporated a similar approach. You can store your images in a (hidden) frame and pass a reference to the frame, just as you would pass a reference to an ImageList to the common controls treeview. However your icon images could be stored anywhere. As long as you can retrieve a “StdPicture” handle for each icon and add it to a “collection” that’s all we need.

Label formatting

Label formatting is available to you with code as simple as:

cNode.Bold = True
cNode.BackColor = RGB(255, 255, 220)    ' pale yellow
cNode.ForeColor = RGB(180, 0, 0)    ' dark red

Make sure you do not use code like:

cNode.Control.BackColor = RGB(255, 255, 220)    ' pale yellow

When you are building the set of nodes, the controls of the treeview have not yet been created (this is done when .Refresh is called). Using the properties the node class itself exposes ensures those are applied when the nodes are created. Only once the treeview is fully initialised and refreshed you can access the properties of the cNode.Control.

In addition, the treeview will automatically pick up the default font settings of its parent (frame) control, so controlling appearance of the treeview starts as easy as setting properties of the frame you'll use to host the treeview. I'll explain this on the next page.

Functionality

We've already implemented quite some functionality. Here is what you can do "out of the box":

Function
Description

Collapsing and expanding

Clicking the expand/collapse buttons does as advertised: it expands or collapses the tree.

Navigation using mouse and keyboard

Navigation using mouse and keyboard works just like in the "old" treeview. Right and left arrow expand or collapse, up and down arrow move up or down the tree. Page-up and down just work.

Editing nodes

You can use F2 to edit a node. Double-clicking a node also puts it in edit mode. This option can be enabled or disabled by setting a property value.

Drag and drop

We're working on that.

Copying, moving (cutting) and pasting

Copy and move functions are built in, you can copy or move single nodes or entire branches. You can do that silently but we have also made it easy for you to trap user actions on the selected node, eg Ctrl-c, Ctrl-x, Ctrl-v. You can include your own code to validate the intended actions, eg only allow copy between similar levels, then instigate the copy or move.

Sort

An efficient sort routine has been devised especially for this treeview. Currently it only operates at a given node level, however options for sort order and text/binary are included.

Properties

There is quite a number of properties you can change. To give you an idea, some are listed below. There are more properties and methods, which are documented in the Excel download.

Property
Description
Remarks

Full Width

True: Node caption widths extend beyond the width of the treeview, makes for clear highlighting of the selected node and if backcolor's are applied.

False: label widths are 'autosized' to the text
If node icons are used an additional image control is created for use with 'full width'

A large tree using node icons will load faster if 'full width' is not applied.

Checkboxes

True: show checkboxes.
Press spacekey or click to change the value.

The check change event is trapped in the form, and the info label updated.

Allow Editing

User can manually edit the node.
Double click or press F2 on a selected node.

Key Enter to apply the edit or Esc to abort.

Show Lines

Whether or not to show lines may be a matter of aesthetics or needs depending on the tree.
Try experimenting with different indentation widths (see the spin button).

In a large tree start-up time will be considerably faster if lines are not shown.

Root button

True: the entire tree can be collapsed to the Root.
False: the tree can only be collapsed to the first level.

Expander icons

The expander buttons can be Labels with +/- characters toggled, or pairs of icons.
If icons are used the images must be available in the workbook, on a sheet or as in the demo hidden on the form.

The demo includes pseudo WinXP and Win7 Explorer type expander icons, but you can use any icons of your choice, or no icons.

Indentation

Default is 15 points

NodeHeight

The treeview already automatically adjusts its Node height to the Font size or checkbox size or Icon size, whichever is the larger.

It's probably best not to adjust Node height.

Font size

The font size and other default label properties are adopted from the parent frame.

Change at design time only.

RootNodes

The root nodes of the tree

Nodes

All Nodes of your tree

Methods

Method
Description
Remarks

ActivateNode

Activate a node based on the key.

Copy

Copies the node put on the 'clipboard'

Move

Move source node + children to destination node.

NodesClear

Equivalent to Treeview.Nodes.Clear.

NodeRemove

Remove Node, its children and grandchildren.

Refresh

Adds and displays all the controls for the Treeview for the first time. ALso displays and repositions node controls as required.

SetTreeExpansionLevel

Updates the expanded properties according to lLevel.
Called recursively.

TerminateTree

Removes the treeview from memory.
Must be called before your userform goes out of scope.

ScrollToView

Ensures the node passed to the method is scrolled into view.

Events

Currently we have made available a limited set of events:

Event
Descrription

Click event

Fires when you click any node.

Node check event

Fires when you click the checkbox of a node.

After label edit event

Fires after editing a label.

Key down event

Fires when you press a key. The demoform included in the sample project shows how to implement copy and paste.

Mouse events

All mouse events are pushed through using a single MouseEvents event.

Add your own events

It isn't hard to add your own events, e.g. it takes three steps to add a new event for a specific element of the tree:

  1. Add event to the clsNode class for the piece of the tree you need an event for, by using the dropdowns at the top of the code window. Make sure it then calls a Friend sub in the clsTreeView class.
  2. Add an Event declaration to the clsTreeView class (like shown above) and a friend sub that raises that event when called from clsNode.
  3. Add an event handler to your userform.

Next: using this treeview in your VBA project.

 


 


Comments

Showing last 8 comments of 73 in total (Show All Comments):

 


Comment by: Pete (20-2-2021 18:40:00) deeplink to this comment

Thank you, but I really don't need other features. In fact, I cut out quite a bit of the functionality that you already have, partly for simplicity, partly for speed. This app uses a subset of what you built originally, but I would like to add the automatic scrolling. The drag-and-drop that I wrote works nicely, even with a large tree, but it can't go beyond what is displayed. You write that is is possible to do the scrolling, and I know that is possible - the ScrollToView routine does it quite nicely. My issue is detecting WHERE the cursor is in the control at the moment I initially grab an element - the 'altitude' inside the box. Once I have that, I can compute everything else - the proximity of the border, and how much to scroll the display. Can you tell me how to get that one piece of information?


Comment by: Peter Thornton (20-2-2021 20:42:00) deeplink to this comment

Hi Pete,

First a some misconceptions:
1 You say what you have so far is no problem in a large tree, but that's probably because so far you've only tested D&D in a static frame, showing perhaps only a small part of the tree.
2 I'd be surprised if removing features, as you say partly for speed, noticeably improves speed. Performance in the free version reduces exponentially the larger the tree, this is because each node involves several controls, 'features' make very little difference in this respect.
3 What's involved to scroll the frame with D&D in response to the mouse is not a matter of simply adapting ScrollToView.

Scrolling the frame for D&D purposes involves a fair amount of code, and some unexpected catches to handle. It's not viable to post here as a few lines!


Comment by: Pete (20-2-2021 21:50:00) deeplink to this comment

1. Perhaps we have different ideas of what is large. This tree has a bit over 60,000 elements, and most of the lag time is loading the data from an ODBC server. I get around that by loading only parts, and loading expanded elements on demand. I have tested it with far more elements than can be shown in a the frame, and the D&D works fine, as long as the elements to be dragged from and to are in frame. When they are out of frame, it doesn't work at all, because of the scrolling issue, which is what I'm trying to fix.

2. Removing features DID improve speed. I didn't conduct any timing tests, so I can't tell you by how much, and it was interspersed with limiting the amount of data pulled in over the network, but it did help. And it made it much simpler to cut out things that I wasn't using, so that troubleshooting subsequent tuning efforts was lots easier.

3. Well, I don't know about that. I see no reason why it wouldn't work, but maybe there are things I don't know about. In any case, I'm not asking you to do all the work for me, only if you know how to get the height inside the control at the moment an element is clicked. I tried various MouseMove events in the controls, and none of it worked, which is why I wrote you. That one thing is all I'm after at the moment, not for you to write and post an entire scrolling routine. Do you know of a way to get that number?


Comment by: Peter Thornton (21-2-2021 16:55:00) deeplink to this comment

I’d say 60k nodes is a large tree, and way beyond design for the ‘free’ version! (hence the ‘pro’). Unless your connection is particularly slow by far the most time involved with such a tree is creating the node controls, exponentially more with bigger numbers, whereas getting data over the connection will normally remain linear.

Though note controls are only built ‘on-demand’ first time required to display, so apply Expanded = False for most parent nodes when populating. Although that can dramatically help load time, once fully created such a tree will be slow to respond and difficult to navigate.

I can’t think which properties that if removed would make a significant difference to load time. Though not using properties that require additional controls would help, such as not showing lines or icons.

I’m confused as to which approach you are using for D&D. I first assumed you had rolled your own, as the MSForms events won’t work between the Treeview and Access controls but the frame should automatically scroll if you were. Yet you say you can't return coordinates in the move events, they should work fine whereas they won’t with the MSForms while dragging.

Whichever approach you're using you’re using you could get the coordinates with a mouse-hook, though probably other ways. It’s difficult to give you the simple answer you’re looking for, though even once you get it scrolling there are other catches to contend with. If you want to continue this further it might be easier if you contact me off-line.


Comment by: Mark C (27-9-2021 10:02:00) deeplink to this comment

Trying to implement it with my access project. It would be great to have double click event to expand subchild as default when editing is not allowed. :)


Comment by: Peter Thornton (27-9-2021 10:33:00) deeplink to this comment

Hi Mark,

You can adapt the code to include the double click event if you follow the comments starting under if you follow the comments starting under 'Event Click', near the top of clsTreeview. Then it's fairly straightforward to include the code to toggle expand/collapse in the event, either in your project or within the treeview classes.

FYI the pro version includes an optional property 'DblClickExpand' which does exactly what you ask, also the full range of events and much else.


Comment by: Mark C (8-10-2021 02:17:00) deeplink to this comment

Hi Peter,

Thank you for the instruction. :)

I notice there might be a bug with modal popup form.
With demo access file you provided,
1. creat frm01, set as pop up form, and modal mode as true
2. add a button on frm01, simply use it add code "DoCmd.OpenForm "frmDemo"
3. Open frm01 and click the button to open frmDemo; close frmDemo, and the whole access program will be minimized. It should just close frmDemo and leave frm01 on screen.
4. To advoid it, set frm01 modal mode as false; Or just delete subTreeView control from frmdemo.
I dont' know what is causing the problem. Could you have a check?

Thanks,


Comment by: Peter Thornton (8-10-2021 12:09:00) deeplink to this comment

Hi Mark,

I can reproduce what you describe, I'm not sure why that occurs either.

However this does not seem to occur with the 'pro' treeview, so it might be related to how the 'userform' is handled which is much improved in the pro version.

You are the first person in 8 years to notice this:)


Have a question, comment or suggestion? Then please use this form.

If your question is not directly related to this web page, but rather a more general "How do I do this" Excel question, then I advise you to ask your question here: www.eileenslounge.com.




To post VBA code in your comment, use [VB] tags, like this: [VB]Code goes here[/VB].