I am creating a resource-intensive dashboard application that will have many areas of data visualization. I am thinking that it would be best to use a frame and load the pages needed one at a time using WPF pages. These pages will also have different data contexts, security restrictions, etc. But, another developer says I can accomplish the same thing using a TabControl.
Does a TabControl load all the items in all the tabs at once, on application startup? Or, can I load them lazily as needed like with WPF pages (page only loads content when navigated to)? Also, can you have different data contexts per each item in a TabControl?
In WPF you can use UI Virtualization which means that only the visible controls are initialized and rendered. As far as I know, the TabControl does not support UI Virtualization by default but maybe you can add it manually or use another control. Maybe you want to have a look at the following article which presents some performance tips. There is also mentioned that there is a difference between UI and Data Virtualization. Not showing the controls does not mean that the underlying data are not in memory. All your binding targets will be loaded, but the controls will not be rendered.
To your second question: Yes, every TabItem can have its own DataContext. If you use a TabControls ItemsSource to bind a list of items, the DataContext for every TabItem will be one item of the list. If you manually add TabItems, you can set the DataContext like that:
<TabControl>
<TabItem DataContext="{Binding Context1}" />
<TabItem DataContext="{Binding Context2}" />
</TabControl>
It is more complex than you would guess. If you bind to Tab Collection (think MVVM) then the tab only get created when it is selected. And with a Collection if you leave a tab and come back it gets built AGAIN. If you create the tabs in XAML then the tabs are all built when the windows loads. Yes you can have different DataContext for each tab. What I do for lazy loads is bind to the TabItem property IsSelected and if it is false all the Properties in the class just return a (fast) static type compliant value. If IsSelected is changed to true then I load the real values and call NotifyPropertyChanged (and I save the real values).
I use the heck out of this were I load a big objects and one tab is a summary. Tabs do not virtualize but if you have big lists then for sure use virtualization in the tab. You can use BackgroundWorker to create properites but once it returns and you bind that returned value the UI locked until the UI control is rendered. For me reuse of a single frame versus tabs is a UI thing. Just to break up code I typically load a tab with a frame and a page (and I typically pass data to the page in the ctor to load dynamic content).