In computer programming, a widget is an element of a graphical user interface that displays an information arrangement changeable by the user, such as a window or a text box. The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given...
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
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s or common distance units, so a number of popular widget toolkit
Widget toolkit
In computing, a widget toolkit, widget library, or GUI toolkit is a set of widgets for use in designing applications with graphical user interfaces...
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
In computer programming, XUL , the XML User Interface Language, is an XML user interface markup language developed by the Mozilla project. XUL operates in Mozilla cross-platform applications such as Firefox...
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
Windows Forms is the name given to the graphical application programming interface included as a part of Microsoft .NET Framework, providing access to native Microsoft Windows interface elements by wrapping the extant Windows API in managed code...
Extensible Application Markup Language is a declarative XML-based language created by Microsoft used for initializing structured values and objects. It is available under Microsoft's Open Specification Promise...
).
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
Swing (Java)
Swing is the primary Java GUI widget toolkit. It is part of Oracle's Java Foundation Classes — an API for providing a graphical user interface for Java programs....
The Java Class Library is a set of dynamically loadable libraries that Java applications can call at run time. Because the Java Platform is not dependent on any specific operating system, applications cannot rely on any of the existing libraries...
In computer programming, XUL , the XML User Interface Language, is an XML user interface markup language developed by the Mozilla project. XUL operates in Mozilla cross-platform applications such as Firefox...
, one can use elements like the 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
The DockPanel container lays out children components according to their Dock properties.
WindowTitle="myDock Panel"> Top 1 Top 2 Top 3 Top 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.
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.FlowLayout;
import java.awt.Container;
public class LayoutExample extends JFrame {
public LayoutExample {
this.setTitle("FlowLayoutDemo");
// get the top-level container in the Frame (= Window)
Container contentPane = this.getContentPane;
// set the layout of this container
contentPane.setLayout(new FlowLayout);
