widget toolkit
A widget toolkit, widget library, GUI toolkit, or UX library is a library or a collection of libraries containing a set of graphical control elements (called ''widgets'') used to construct the graphical user interface (GUI) of programs.
Most widg ...
s which have the ability to lay out
graphical control element
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 ...
s by their relative positions without using distance units. It is often more natural to define component layouts in this manner than to define their position in
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the smal ...
s or common distance units, so a number of popular
widget toolkit
A widget toolkit, widget library, GUI toolkit, or UX library is a library or a collection of libraries containing a set of graphical control elements (called ''widgets'') used to construct the graphical user interface (GUI) of programs.
Most widg ...
s include this ability by default. Widget toolkits that provide this function can generally be classified into two groups:
*Those where the layout behavior is coded in special graphic containers. This is the case in
XUL
XUL ( ), which stands for XML User Interface Language, is a user interface markup language developed by Mozilla. XUL is an XML dialect for writing graphical user interfaces, enabling developers to write user interface elements in a manner sim ...
and the
.NET Framework
The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
widget toolkit (both in
Windows Forms
Windows Forms (WinForms) is a free and open-source graphical (GUI) class library included as a part of Microsoft .NET, .NET Framework or Mono Framework, providing a platform to write client applications for desktop, laptop, and tablet PCs. While ...
and in
XAML
Extensible Application Markup Language (XAML ) is a declarative XML-based language that Microsoft developed for initializing structured values and objects. It is available under Microsoft's Open Specification Promise.
XAML is used extensively ...
).
*Those where the layout behavior is coded in layout managers, that can be applied to any graphic container. This is the case in the Swing widget toolkit that is part of the
Java API
There are two types of Java programming language application programming interfaces (APIs):
* The official core Java API, contained in the Android (Google), SE (OpenJDK and Oracle), MicroEJ. These packages (java.* packages) are the core Java la ...
.
Examples
XUL
In
XUL
XUL ( ), which stands for XML User Interface Language, is a user interface markup language developed by Mozilla. XUL is an XML dialect for writing graphical user interfaces, enabling developers to write user interface elements in a manner sim ...
, like th vbox container to stack components on top of each other.
This piece of code shows 3 buttons stacked on top of each other in a vertical box.
XAML
Th DockPanel container lays out children components according to their ''Dock'' properties.
Top 1Top 2Top 3Top 4
This code shows 4 text blocks on top of each other.
Java
The layout manager arranges components in a directional flow, much like lines of text in a paragraph. It arranges components horizontally until no more components fit on the same line, then it places them on another line. Other layout managers are GridLayout managers which arrange the components in grid form and BorderLayout managers which also arranges the component in five parts of the frame, thus: south, north, west, east and center.
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.FlowLayout;
import java.awt.Container;
public class Example
This code shows 5 buttons alongside each other on the same line: