ActiveTreeView
Provide an advanced interface for displaying hierarchical data.
Infragistics 社の製品
1996 年より日本国内にてComponentSourceで販売中。
ActiveTreeView is a 32-bit ActiveX component designed for drill-down capabilities for databases. It extends the tree view control inherent to Visual Basic and features three modes of connectivity. ActiveTreeView is designed to operate in all ActiveX-compliant host environments and appears just like the Office 97 tree structures. Features include ToolTips, ScrollBarTips, LineTips, MultiColumns, and MultiSelect for selecting multiple items. Infragistics ActiveTreeView was formerly called Sheridan ActiveTreeView.
ActiveTreeView also includes:
The ActiveTreeView control has several operational modes: AddItem, Semi-Virtual, and Virtual. In AddItem mode, the ActiveTreeView stores all nodes in memory. Semi-virtual mode and Virtual mode both use events to retrieve data for display by the tree on an as needed basis. In semi-virtual mode, the data is retrieved and stored in memory in a manner similar to AddItem mode. In virtual mode, data is retrieved and discarded - only the data displayed in the tree is in memory at any given time.
AddItem mode
Nodes are added to the tree in the same way that list items are added to a List control. The control stores all nodes in memory. AddItem mode is the simplest mode to use, so it is a good way to get started with using the control's basic features.
Semi-Virtual Mode (OnDemandKeep)
In OnDemandKeep mode, the control is populated with data in response to the user scrolling through the tree. Two events (OnDemandPrepare and OnDemandFetch) are fired to populate the tree with data. OnDemandPrepare is fired first and is used to prepare the data that will be added. OnDemandFetch is then fired to actually populate the tree with the prepared data. As the user scrolls more data into view, that data is stored by the control, much like in AddItem mode. If the user scrolls to an area of the control they have already seen, data is immediately available.
Virtual Mode (OnDemandDiscard)
In the OnDemandDiscard mode, as nodes are scrolled out of view, they are discarded. This means that if you scroll back to that area, the events are fired again, since those nodes no longer exist and have to be recreated. However, in the OnDemandKeep mode, once a node has been added to the ActiveTreeView, it is stored until it is either explicitly deleted or the control itself is destroyed.
Adding Images to Tree Nodes
Because it is a direct replacement for the Microsoft TreeView control, the ActiveTreeView supports the use of the ImageList control to supply pictures. The ImageList control, included with the Professional and Enterprise editions of Visual Basic, is one of Windows' common controls. It has the sole purpose of storing images for use by other controls within the application. Each image stored in the ImageList control is a member of a collection, with its own Key and Index values. The programmer uses these values to apply specific images to specific picture-related properties in the application. Pictures stored by a given ImageList control are all the same size, and can be easily accessed by using standard Visual Basic collection properties and methods.
The ActiveTreeView comes equipped with its own internal image list in the form of an Images collection, which eliminates the need for an external ImageList control to store pictures. The ActiveTreeView's built-in Images collection is nearly identical in function to the stand-alone ImageList control. It uses the same properties and methods for adding, manipulating and deleting the images it stores. The ActiveTreeView property pages provide a custom interface to the Images collection, making it easy to add the pictures you need for your application.