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A tree view is a
graphical widget A graphical widget (also graphical control element or control) in a graphical user interface is an element of interaction, such as a button or a scroll bar. Controls are software components that a computer user interacts with through direct m ...
(graphical control element) within a
graphical user interface A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
(GUI) in which users can navigate and interact intuitively with concise,
hierarchical A hierarchy (from Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that are represented as being "above", "below", or "at the same level as" one another. Hierarchy is an importan ...
data presented as nodes in a tree-like format. It can also be called an outline view.


Appearance

A tree view is usually a vertical list of nodes arranged in a tree-like structure. Each node represents a single data item, displayed as an indented line of text or a rectangular box. The indentation (and sometimes a line drawn between nodes) is used to indicate levels of hierarchy. Every treeview has a ''root node'' from which all nodes descend. Below the root node and indented to the right are its child nodes. Each node has exactly one parent node and can have zero or more child nodes. If a node (other than the root node) has a child or children, it is called a ''branch node''. If it has no child, then it is a ''leaf node''. This creates a hierarchical tree-like structure, with branches and subbranches emerging downward and rightwards. The nodes can be differentiated by different colors, icons and fonts to represent the nested relationship between parent nodes and child nodes. An item can be ''expanded'' to reveal subitems, if any exist, and ''collapsed'' to hide subitems.


Features


Interactivity

Tree view allows users to interact with hierarchical data in a variety of ways, such as : * expanding and collapsing nodes to reveal or to hide their child nodes and thus navigate through the tree structure according to one's needs. * search and filter nodes based on specific criteria such as date. * renaming or deleting using context menus. * copying and moving (dragging and dropping) nodes to other sections of the tree to rearrange them. * opening a node in a separate window.


Customizability

Tree views can be customized for visual appeal and efficiency in the following ways: * Input methods : Tree views can be customized to support various input methods such as mouse, keyboard, and touch input so that users can interact using their preferred method. Users can use their mouse to click on a node to select it, move their mouse to drag and then release the mouse button to drop nodes to rearrange them. They can also use keyboard shortcuts to navigate and interact with the tree. * Look and feel : Developers (and sometimes users) can tailor the look and feel of tree views as well to match specific visual requirements of certain applications. Icons, fonts and colors used to display nodes, animations and effects to represent node expansion and collapse, and custom behaviors for drag and drop actions can be implemented. The context menu options can be customized for an application so that users can only perform specific actions on nodes. * Accessibility : tree views can offer accessibility features for users with disabilities.


Advantages

Tree views offer the following advantages : * They display hierarchical data in a concise and easy-to-follow format, so that users can easily walk through and interact with the data. * They are customizable, so their appearance and behavior can be tailored to meet specific requirements of an application. * They are interactive and allow the use of different input methods. * They are flexible and potent navigational tools which can be used in a variety of applications (such as file managers)


Disadvantages

* If the nested or hierarchical relationship of items is not to be emphasized, then tree view would not be the optimal choice. A regular list would be more appropriate. * For large amounts of data or deeply nested hierarchies, tree views can become visually disorderly and difficult to navigate, leading to inefficiency and productivity loss because users would spend more time walking through the structure than working with the data. * They are more complex and thus more difficult to maintain than simpler structures like lists and tables. * For the developers, customization options with animations and complex behaviors can increase time spent on implementation and debugging.


Application

Tree views are used in situations where hierarchical data needs to be displayed and navigated in a graphical interface. For example, they have been used in: *
file manager A file manager or file browser is a computer program that provides a user interface to manage computer files, files and folder (computing), folders. The most common Computer file#Operations, operations performed on files or groups of files incl ...
s to display the hierarchical structure of directories and files residing in a computer file system so that users can navigate the directory tree and open, close and manage their files more efficiently. * email clients to display the hierarchical structure of email folders and messages, helping users to view and reply to email messages, and manage their inbox. * organizational charts to display the hierarchical structure of an organization's employees and departments. * network topologies * programming frameworks for building graphical applications. *
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...
documents to present hierarchical data. *
outliner An outliner (or outline processor) is a specialized type of text editor (word processor) used to create and edit Outline (list), outlines, which are text files which have a tree structure or a tree view, for organization. Textual information is co ...
applications (as extended tree view), where each node consists of editable text.


See also

*
Directory (file systems) Directory may refer to: * Directory (computing), or folder, a file system structure in which to store computer files * Directory (OpenVMS command) * Directory service, a software application for organizing information about a computer network's u ...
- an example of application of tree views *
File manager A file manager or file browser is a computer program that provides a user interface to manage computer files, files and folder (computing), folders. The most common Computer file#Operations, operations performed on files or groups of files incl ...
*
Genealogy software Genealogy software is computer software used to record, organize, and publish genealogical data. Features At a minimum, genealogy software collects the date and place of an individual's birth, marriage, and death, and stores the relationships ...


References


External links


Treeview in pure HTML+CSS



Tree view control in the Win32 API (MSDN)


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Extended TreeView for .NET WinForms

TreeView Control in ASP.NET 2.0

Interview with Henk Hagedoorn, developer of first tree-view PIM
Graphical control elements {{GUI-stub