Visual Basic 2008 Recipes: A Problem-Solution Approach

5.6. Show a Just-in-Time Directory Tree in the TreeView Control

Problem

You need to display a directory tree in a TreeView control. However, filling the directory tree structure at startup is too time-consuming.

Solution

Fill the first level of directories in the TreeView control and add a hidden dummy node to each directory branch. React to the TreeView.BeforeExpand event to fill in subdirectories in a branch just before it's displayed.

How It Works

You can use recursion to build an entire directory tree. However, scanning the file system in this way can be slow, particularly for large drives. For this reason, professional file management software programs (including Windows Explorer) use a different technique. They query the necessary directory ...