Data Virtualization

Data virtualization lets FlexGrid handle very large data sets by loading data incrementally as the user scrolls, instead of all at once. This overview gives a quick snapshot of each subtopic and when to use it.

Data Virtualization

Topic	Use Case
On Demand Mode	Use when the grid cannot know the total row count up front — for example, paging through an API that returns one chunk at a time. Inherit `C1CursorDataCollection<T>`, override `HasMoreItems` (returns `true` while more pages remain) and `GetPageAsync` (returns a page of items and a continuation token). The scroll bar grows and repositions as more data arrives, because the grid never has a fixed total.
Virtual Mode	Use when you know the total row count in advance — the grid then sizes the scroll bar correctly and loads only the visible pages. Inherit the abstract `C1VirtualDataCollection<T>`, override `GetPageAsync`, and return the total count alongside each page of items. Assign the collection to `ItemsSource`.

Topic

Use Case

On Demand Mode

Use when the grid cannot know the total row count up front — for example, paging through an API that returns one chunk at a time. Inherit C1CursorDataCollection<T>, override HasMoreItems (returns true while more pages remain) and GetPageAsync (returns a page of items and a continuation token). The scroll bar grows and repositions as more data arrives, because the grid never has a fixed total.

Virtual Mode

Use when you know the total row count in advance — the grid then sizes the scroll bar correctly and loads only the visible pages. Inherit the abstract C1VirtualDataCollection<T>, override GetPageAsync, and return the total count alongside each page of items. Assign the collection to ItemsSource.