GLOSSARY

accelerator     A key combination, such as Control-S, that allows selection of menu items, buttons, and other controls using the keyboard.

accessibility     An accessible application is one that can be used by people with impaired vision or other disabilities.

ANSI     An acronym for American National Standards Institute, an organization that defined a standard character set. wxWidgets distinguishes between compilation in ANSI and Unicode mode. In ANSI mode, character encodings must be used to switch between languages, but this is not necessary with Unicode. In this context, ANSI and ASCII are interchangeable, as the differences are slight.

alpha channel     Extra information in a bitmap that can be used to draw the bitmap with translucency. Each pixel in the bitmap has an 8-bit alpha value indicating the pixel’s intensity.

API     Application Programming Interface, the published set of classes and functions that a library offers to an application.

assertion     A test supplied in debug mode that causes an error message to be shown if the test fails.

bakefile     A makefile generation system used within wxWidgets that can also be used for other libraries and applications.

bit-list     An integer containing flags that are combined with the binary OR operator (“|”)—for example, wxSUNKEN_BORDER|wxTAB_TRAVERSAL. The presence of a flag can be tested by using the binary AND operator (“&”).

block     Describes the suspension of a function’s execution while waiting for something, such as for a modal dialog to be dismissed or data to become available on a socket.

bundle     A Mac OS X application is packaged in a bundle, which has a specific directory structure and is described by an XML file.

Carbon     The Apple API supplied for compatibility with both Mac OS 9 and Mac OS X, used by the wxMac port to implement GUI functionality.

client area     The area in which an application can draw or place child windows. For example, the client area of a frame with a menu bar is the portion below the menu bar.

client data     Arbitrary user data that can be associated with a window or its items. In some cases, it is deleted automatically by the window, and in others cases, it is the application’s responsibility.

Cocoa     Mac OS X’s native API for GUI functionality, used by the wxCocoa port.

control     A window that displays a value that can usually be changed by the user. It is also known as a “widget”. There is no absolute distinction between a control and a window, but you might use “control” to distinguish between a control on a dialog, such as a button or list box, and a window that manages other windows, such as a splitter window.

character encoding     A specification that maps raw values to actual characters. Because ASCII cannot encompass all languages, there are many encodings for different languages. Using Unicode eliminates the need for separate encodings because it allows multiple bytes per character.

cross-platform programming     Programming for more than one platform.

default     The value or behavior that is assumed to be present if no other specification has been made.

device context     An object on which an application can draw. For example, a wxClientDC object can be used to draw on a window.

dialog     A window that is shown to convey information or present choices.

double-buffering     A flicker-reduction technique whereby graphics are drawn off-screen on a bitmap before being transferred to a window.

dynamic event handler     A handler that has been installed during the running of the program, rather than by “static” event table entries that are built into the program at compile time.

cache     A data structure used to speed up an operation by storing results from previous operations.

embedded system     Refers to a small or industrial device, in contrast with a desktop system—for example, a mobile phone, PDA, or wireless terminal. wxWidgets supports embedded systems via wxWinCE, wxGTK, wxMGL, and wxX11.

event     In wxWidgets, an action taken by the user (such as a button press), the operating system (such as a color change event), or the framework (such as a dialog initialization event).

event loop     Code that waits for events and dispatches them to suitable event handlers that can handle them. There is a “main” event loop, and showing a modal dialog causes a further event loop to be entered until the dialog is dismissed.

event table     A mapping that tells wxWidgets how to route events to handler functions by specifying an event type and identifier that should match.

focus     The window that has the focus can accept keyboard input.

frame     A “top-level” window used to contain other windows, menu bars, toolbars, and so on.

framework     A set of classes for handling a set of related problems, providing default functionality that can be replaced. wxWidgets is a GUI framework.

generic     Used to describe classes that are implemented by wxWidgets itself, where there is no “native” equivalent.

GTK+     The widget set used by applications that are designed for the GNOME desktop environment, which is popular on Linux.

GUI     Graphical User Interface, a term applied to programs and operating systems that support a windowing environment and pointing device.

IDE     Integrated Development Environment, a tool that handles many aspects of the development process, such as editing, compiling, and debugging.

identifier     An integer used for identifying windows and other objects and mapping commands to event handler functions. wxWidgets provides standard identifiers such as wxID_OK.

idle event     An event sent to each window of an application after normal events have all been processed to allow low-priority tasks to be performed.

image     Any bitmap (pixel-based) graphic; image classes in wxWidgets include wxImage, wxBitmap, wxCursor, and wxIcon.

internationalization     The process of converting an application to display and handle information in more than one language. Also known informally as “i18n” (“i” followed by 18 characters, followed by “n”).

locale     The representation of a geopolitical location that has potentially distinct properties for date and currency formats, character sets, and so on. This is represented in wxWidgets by wxLocale.

makefile     A file that defines how a set of source files is used to create an executable, processed by a program called “make.” Some development tools (such as DialogBlocks) generate and invoke makefiles.

manifest     Under Windows, refers to an XML file that must accompany an executable (or be compiled into its resources) for the application to take advantage of XP themes.

mask     A monochrome (1-bit) bitmap that specifies the visible parts of another bitmap. A bitmap may have a mask, an alpha channel, or neither.

MDI     Multiple Document Interface, from the Windows user interface style where the main window fully contains any document windows.

MFC     Microsoft Foundation Classes, a framework for building Windows applications.

MGL     A low-level 2D graphics API by SciTech Software Inc. for Linux, DOS, and embedded systems, supported by the wxMGL port.

mnemonic     An assigned character in a user interface element such as a button that gives a keyboard equivalent to mouse input.

modifier key     A key, such as Control or Shift, that generally needs another key to be pressed to generate input.

modal     A modal dialog “blocks” program flow when shown, disabling other windows, and therefore puts the application in a particular mode. A modeless dialog does not usually interrupt program flow or disable other windows.

monolithic     wxWidgets can be compiled as one large library (“monolithic”) or as a collection of separate libraries (“multilib”).

Motif     A widget set layered on top of X11 and supported by wxWidgets.

multi-platform application     An application that can be compiled to run on several platforms without significant changes to the source code.

multilib     Used to distinguish between a build of wxWidgets that splits it into several libraries, compared with a “monolithic” build, where there is only one wxWidgets library file.

native     A widget is said to be “native” if it uses an implementation supplied by the vendor of the underlying toolkit or operating system. Examples include wxButton on Windows, GTK+, and Mac OS X.

OpenGL     A popular 3D graphics language available on most platforms, supported in wxWidgets through the wxGLCanvas class.

platform     Denotes a particular combination of hardware, operating system, windowing environment, and underlying widget set. For example, GTK+ on i386 Linux, Motif on i386 Linux, Windows, and Mac OS X represent distinct platforms. Depending on context, platform may also refer only to a distinct operating system or a family of operating systems, such as “the Microsoft Windows Mobile platform.”

port     An implementation of the wxWidgets API for a particular operating system and widget set. For example, the Windows port is wxMSW, and the GTK+ port is wxGTK.

PNG     Portable Network Graphics, a popular file format for images, invented to replace the GIF format.

propagating event     An event that can be handled by an ancestor of the object that generated the event; for example, if a button is on a panel in a frame, the button click event may be handled by the button itself, the panel, or the frame containing the panel.

quantization     The process of reducing the number of unique colors in an image without severely degrading it.

RAD     Rapid Application Development, used to describe tools such as DialogBlocks and wxDesigner that boost productivity.

reentrant     Code that is executed recursively (entered multiple times), possibly with harmful consequences.

resource     An overloaded term that means different things in different contexts. A wxWidgets resource is generally an element in an XRC resource file. A bitmap resource may refer to binary data added to a Windows application’s executable by the Windows resource compiler, or it may refer simply to extra files required by an application.

resource handler     A class whose instance is plugged into the wxWidgets resource system in order to interpret values specified in an XRC file and apply them to a new resource.

RGB     The Red, Green, and Blue values that form a color specification.

RTTI     Run-time type information, whereby a class is annotated so that applications can query aspects of the class, such as its name and base class.

static control     A control that is for display only and that does not support user input.

sizer     A container for laying out windows or further sizers in a hierarchy.

stock     Refers to an object or identifier that is provided by wxWidgets or by the underlying toolkit, for convenience or to promote standardization. Stock cursors, stock colors, and stock buttons are examples of this usage.

stream     An instance of a class that handles sequential input or output for a particular data source. It is a higher-level construct than the file, being applicable to arbitrary data sources, and wxWidgets defines its own set of stream classes.

theme     Some desktop environments let the user select a different look and feel, varying the way windows are drawn, colors used, and so on. wxWidgets will use the current theme for its widgets where possible.

transparency     Usually refers to the 1-bit “mask” that can be associated with bitmaps to determine which parts of the image should be visible, in contrast with an alpha channel, which enables “translucency” (the blending of an image with the graphic underneath).

transient window     A window that shows for a short time and normally has very little decoration. Examples are menus and tooltips.

UI update event     A user interface event generated by wxWidgets in idle time to give the application a chance to update the state of a window.

Unicode     A specification that eliminates the need for separate encodings by allowing multiple byes per character.

universal widget set     A term used to describe the widget set (wxUniversal) that wxWidgets uses where there are no “native” widgets. Used in wxX11 and wxMGL.

validator     An object that can be associated with a window that checks whether the user has entered valid data. It can also transfer data to and from the window, for example at dialog initialization and when a dialog is dismissed, respectively.

virtual file system     A set of classes that enables data sources other than ordinary files to be used. This facility in wxWidgets allows data to be streamed from files within compressed archives, for example.

widget     A window with specific display and input functionality, such as a wxButton.

widget set     A widget set consists of the widgets (or “controls”) that wxWidgets uses to implement its API. Examples are Win32, GTK+, Motif, and wxUniversal (a set of widgets implemented using wxWidgets itself).

Win32     The API for writing GUI applications on Windows, supported by the wxMSW port.

window decorations     The buttons, border, caption bar, and other elements of a top-level window, normally drawn by the window manager.

window manager     The part of the desktop environment that provides decoration for and behavior of top-level application windows. Under X11, the desktop environment such as GNOME or KDE provides window management. Under Windows and Mac OS X, there is no choice of window manager: this function is performed by the operating system.

Windows     The family of operating systems from Microsoft. The use of “Windows” in this book usually denotes the desktop variants, including Windows 2000 and Windows XP.

Windows CE     The family of embedded operating systems from Microsoft, also known as Windows Mobile. It includes the variations Pocket PC, Smartphone, Portable Media Center, and Windows CE .NET.

wxBase     A build of the wxWidgets library with no GUI functionality that can be used to build command-line applications.

X11     The windowing system, and its communication protocol, used on most Unix systems.

XPM     X11 Pixmap, a file format for small images that can be included in C++ source files.