Frequently Asked Questions

Some questions and issues surface regularly on the Forums or in emails. This section has several of the most common questions. Please read the questions before asking questions on the Forum. Several people have been known to have blood pressure problems.

Can an ObjectListView have rows of different heights?

No.

ObjectListView is a wrapper for the underlying ListView. It makes a ListView much easier to use, but it can’t change the control’s basic behaviour. One limitation of a ListView is it that cannot have rows of different heights. There is no way to make one row be taller than other rows. It’s just not possible.

If being able to have rows of different heights is essential to you, ObjectListView is not your solution. You may want to consider Matthew Hall’s excellent XPTable and its update project, as well as Lee Paul Alexander’s fantastic Outlook-style list.

Can I use ObjectListView in a commercial application?

The code on SourceForge is released under GPLv3. The GPL is a viral license, meaning that if you use some GPL-covered code in your application, your application must also be covered by GPL. This is generally not what commercial developers want. (I am not a lawyer. This is not legal advice. It could be completely wrong).

However, if you wish to use this code in a commercial application, please contact me: phillip_piper@bigfoot.com .

Why doesn’t the ObjectListView auto-update when I change my model objects?

I have ObjectListView that’s showing my model objects. But when I change the values in my model, the ObjectListView doesn’t update. What’s going wrong here?

Nothing. That’s what it is supposed to do.

The ObjectListView knows nothing about your model objects. It does not know when they have been changed. Only you know that. When you know that a model object has changed and needs to be updated, you can either call RefreshObject() to update just one object, or you can call BuildList() to rebuild everything at once.

DataListView is the exception to this rule. Any change you make to your DataSource should be immediately reflected in the DataListView.

Don’t you have some class diagrams for all this stuff?

There seems to be an awful lot going on here. Don’t you have some class diagram so I can see how things fit together?

Some people love class diagrams. Other regard them as just one more piece of out of date documentation. As of v2.1, these diagrams are accurate.

The basic classes are show here:

More details about the relationship between virtual listviews and their data sources can be seen in this diagram:

Why doesn’t it do some-feature-I-really-want?

It could be that I simply haven’t thought of it. Or it could be that I have thought of it but it just isn’t possible.

Remember that ObjectListView is just a wrapper around ListView. It makes the ListView a little easier to use, and adds some helper functions, but it can’t change the basic behaviour of the control.

Why is the text of the first column indented by about 20 pixels?

This shows up when you have a ListView that doesn’t have an icon in the first column. The control still leaves space for the icon, even when there isn’t one.

If the ListView doesn’t have a small image list, this indent disappears. But as soon as the control has a small image list, even an empty one, the text of the first column will be indented.

So, if you really want to get rid of this indent, make an ObjectListView which doesn’t have a SmalImageList. Be aware that some feature require a small image list and will create one if necessary. These features are:

• sort indicators on column header on pre-XP systems
• subitem checkboxes

I’ve compiled the project for the first time, but I don’t see the ObjectListView in the toolbox

If you are using Visual Studio, check under the Tools>>Options, in the Windows Form Designer category (turn on Advanced settings to see) for a setting “AutoToolboxPopulate.” This should be set to True.

Also, make sure you have a Windows Forms project. ObjectListView is a Windows Forms control: it will not appear in the toolbox for a Windows Presentation Framework project, nor for a WebForms project.

Is ObjectListView thread-safe?

“Thread-safe” is a notoriously slippery term.

If you mean, “Can I do whatever I like with an ObjectListView from various threads at the same time?” the answer is “Probably not.”

If you mean “Can I update the ObjectListView from a background thread?” then the answer is, “Yes, so long as you stick to the primary commands.” Specially, these methods can all be called from background threads, and the control will work as expected:

• AddObject/s()
• BuildList()
• ClearObjects()
• InsertObjects()
• RefreshObjects()
• RemoveObject/s()
• SetObjects()
• Sort()

Does it work with Mono?

As of September 2009, not any more.

It would be possible to make it work with Mono again. Please let me know if you are interested.