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This page intentionally left blank generate, create qr-codes none on java projects UCC.EAN - 128 C HAPTE R E I G HT The Window System One of the most basic thing qr bidimensional barcode for Java s any GUI application needs is the ability to display windows on the screen. Swing provides for this with classes such as JFrame. But this hardly solves the entire problem of windowing for Swing applications.

In a reasonably complex, modern application, quite a bit of plumbing is needed beyond the simple ability to put a window on the screen. An application window will typically contain menus, toolbars, and other common components. Many applications have a concept of selection or context sensitivity certain actions that are represented in menus and toolbars can only be enabled when certain types of things are selected.

For example, a Copy menu item should only be enabled when there is something to copy. Neither the code wiring up Actions to toolbar buttons and menu items, nor that which enables and disables actions depending on the state of components in the application s user interface is too much fun to write and debug. Moreover, it is not the business logic of the application it s just plumbing code needed to give the user access to the business logic of the application.

It is not the best use of an application developer s time to reinvent such logic for every application they write. It would be preferable to have a standard way of doing this sort of thing which can be reused across all applications. Complex applications tend to have more than one logical window master and detail views, lists of les, editors, palettes, property sheets, and other controls are common.

Very often such controls are instantiated on the y in. What the Window System Does mainstream, all a NetBeans- javabean QR Code ISO/IEC18004 based application will need to do is drop in a 3D replacement for the standard Window System implementation. If someone wants to write a Macintosh-oriented implementation that uses some of the different frame peers available on the Macintosh platform to create a more native-feeling, super-Mac-friendly UI, a NetBeans-based application would merely need to replace the JAR containing the Window System with that Macspeci c implementation s JAR to take advantage of it. The application s code need not change at all.

The Window System is component-oriented. Most of the time your code will deal with components you have created; the work of adding them to a GUI container in the main window is taken care of by the Window System. So the Window System API lets you concentrate on the business logic of the application getting the right controls on-screen for the user to interact with, instead of spending your precious time on the plumbing code necessary to realize the components on-screen and to make menu items act on the active component.

. What the Window System Does The Window System handles a QR Code ISO/IEC18004 for Java variety of aspects of user interface state. Logical window management In the NetBeans Window System, application code is concerned with components rather than windows per se. The Window System implementation takes care of creating the main application window (or windows).

Application code uses a JPanel subclass that is part of the Window System API org.openide. windows.

TopComponent. So you write components which are subclasses of TopComponent, de ne which tabbed container they should be opened in, and then give those components to the Window System implementation to manage. Such components are logically separate application windows and for simplicity, documentation will often refer to the Projects Window when the window in question is actually a component in a tab control.

. 8 . The Window System Window state Components in the user interface may be in a combination of states: open, selected, and activated. At any given time, in the entire user interface of an instance of NetBeans, only one TopComponent is activated, meaning that it or its child control has input focus. Within a tabbed container in the NetBeans UI, only one of all the components in the container is selected.

And all components which are open have visible tabs in that tabbed container.3 So a TopComponent can exist without being opened; if it is open it may be selected (its tab is the selected one in the tabbed container it lives in); and it may be active (it or its subcomponent has keyboard focus). Selection management Each TopComponent has two forms of selection:.

Its Lookup a sort of bag- jdk QR Code 2d barcode of-stuff which can contain whatever the author of the component wants to put there. There are some standard API classes that can be put there, such as SaveCookie, or it can contain a component that the author provided, say, to get a java.util.

jar.Manifest object when writing an editor for manifest les. Its activated Nodes an array of zero or more Node objects.

Nodes themselves implement Lookup.Provider (meaning they have a getLookup() method, as does TopComponent). The Explorer API contains components that can show Nodes and conveniently hook those components up to the Lookup of a TopComponent, as described in 9.

As their name suggests, Nodes are hierarchical, tree-node-like objects. The Explorer API provides a number of UI components which can display Nodes to the user in trees, lists, tree-tables, etc. So, a common pattern is to have a child component inside a TopComponent container, which allows the user to select Nodes; the activated Nodes property of the TopComponent will track the GUI selection in the child component, ring changes in its activated nodes property when the selection changes.

The Lookup obtained. 3. If you do not want any t abs at all in your application, you can supply a different UI delegate for tabbed containers, as Geertjan describes in his blog (http://blogs. sun.

com/geertjan/entry/farewell_to_space_consuming_weird)..
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