wxWindows 2 FAQ: General

See also top-level FAQ page.

What is wxWindows?

wxWindows is a class library that allows you to compile graphical C++ programs on a range of different platforms. wxWindows defines a common API across platforms, but uses the native graphical user interface (GUI) on each platform, so your program will take on the native 'look and feel' that users are familiar with.

Although GUI applications are mostly built programmatically, there is a dialog editor to help build attractive dialogs and panels.

You don't have to use C++ to use wxWindows: wxWindows 1 has been interfaced to several interpreted languages, such as CLIPS, Python, Scheme, XLisp and Perl, and there is a Python interface for wxWindows 2.

Can I use wxWindows 2 for both proprietary (commercial) projects, and GPL'ed projects?

Yes. Please see the licence for details, but basically you can distribute proprietary binaries without distributing any source code, and neither will wxWindows conflict with GPL code you may be using or developing with it.

The conditions for using wxWindows 2 are the same whether you are a personal, academic or commercial developer.

Is there support?

No official support, but the mailing list is very helpful and some people say that wxWindows support is better than for much commercial software. The developers are keen to fix bugs as soon as possible, though obviously there are no guarantees.

Who uses wxWindows?

Many organisations - commercial, government, and academic - across the world. It's impossible to estimate the true number of users, since wxWindows is obtained by many different means, and we cannot monitor distribution. The mailing list contains around 300-400 entries which is quite large for a list of this type.

I am about to start a wxWindows 1.xx project. Should I use 2 instead?

wxWindows 2 is still in beta but it's actually pretty useable (Windows, GTK, Motif).

Porting to wxWindows 2 from 1.xx will not be too painful; see the next question for ways in which you can make it easier.

Why would I want to use wxWindows 2 in preference to wxWindows 1.xx?

Some reasons:

How can I prepare for wxWindows 2?

To make porting to wxWindows 2 easier in the future, take a look at some tips for writing existing code in a 2-compatible way.

How much has the API changed since 1.xx?

It's difficult to summarize, but some aspects haven't changed very much. For example, if you have some complex drawing code, you will mostly need to make sure it's parameterised with a device context (instead of obtaining one from a window or storing it). You won't have to completely rewrite the drawing code.

The way that events are handled has changed, so for example, where you overrode OnSize before, you now have a non-virtual OnSize with a single event class argument. To make this function known to wxWindows, you add an entry in an 'event table' using macros. Addition of these macros will eventually be made easier by a tool which will allow selection from a list and copy-and-paste into your editor. This is extended to button presses, listbox selection etc. so callbacks have gone (they may be added back for limited backward compatibility).

The class hierarchy has changed to allow greater flexibility but it probably won't affect your existing application. One exception to this is MDI applications which now use separate MDI classes instead of style flags. As a result, it won't be possible to switch between MDI and SDI operation at run-time without further coding, but a benefit is less interdependence between areas of code, and therefore smaller executable size.

Panel items (now called controls) no longer have labels associated with most of them, and default panel layout has been removed. The idea is that you make greater use of dialog resources, for better-looking dialogs.

What classes have disappeared?

wxForm, wxTextWindow (subsumed into wxTextCtrl).

Does wxWindows 2 mean that wxWindows 1.xx is dead?

While wxWindows 2 is being developed, there will be further patches to wxWindows 1.xx. Obviously we are investing most of our energy into the new code, but we're also trying to fix bugs in the current version.

What platforms will be supported by wxWindows 2?

How does wxWindows 2 support platform-specific features?

This is a hotly-debated topic amongst the developers. My own philosophy is to make wxWindows as platform-independent as possible, but allow in a few classes (functions, window styles) that are platform-specific. For example, Windows metafiles and Windows 95 taskbar icons have their own classes on Windows, but nowhere else. Because these classes are provided and are wxWindows-compatible, it doesn't take much coding effort for an application programmer to add support for some functionality that the user on a particular platform might otherwise miss. Also, some classes that started off as platform-specific, such as the MDI classes, have been emulated on other platforms. I can imagine that even wxTaskBarIcon may be implemented for Unix desktops one day.

In other words, wxWindows is not a 'lowest common denominator' approach, but it will still be possible to write portable programs using the core API. Forbidding some platform-specific classes would be a stupid approach that would alienate many potential users, and encourage the perception that toolkits such as wxWindows are not up to the demands of today's sophisticated applications.

Currently resources such as bitmaps and icons are handled in a platform-specific way, but it is hoped to reduce this dependence in due course.

Another reason why wxWindows 2 is not a 'lowest common denominator' toolkit is that some functionality missing on some platform has been provided using generic, platform-independent code, such as the wxTreeCtrl and wxListCtrl classes.

Does wxWindows use STL? or the standard string class?

No. This is a much-discussed topic that has (many times) ended with the conclusion that it is in wxWindows' best interests to avoid use of templates. Not all compilers can handle templates adequately so it would dramatically reduce the number of compilers and platforms that could be supported. It would also be undersirable to make wxWindows dependent on another large library that may have to be downloaded and installed. In addition, use of templates can lead to executable bloat, which is something wxWindows 2 is strenously trying to avoid.

The standard C++ string class is not used, again because it is not available to all compilers, and it is not necessarily a very efficient implementation. Also, we retain more flexibility by being able to modify our own string class. Some compatibility with the string class has been built into wxString.

There is nothing to stop an application using templates or the string class for its own purposes.

How is wxWindows 2 being developed?

We are using the CVS system to develop and maintain wxWindows. This allows us to make alterations and upload them instantly to the server in Edinburgh, from which others can update their source.

How is wxWindows 2 distributed?

By ftp, and via the wxWindows CD-ROM.

What are the plans for the future?

Currently we're working too hard on getting wxWindows 2 finished (are GUI toolkits ever finished?) to think very far ahead. However, we know we want to make wxWindows as robust and well-publicised as possible. We also want to aim for better platform-independence of resources such as icons and bitmaps, standardising on the PNG for all platforms.

Other possibilities include: DCOM/CORBA compatibility; a wxWindows book; an IDE; other platforms; other interface abilities such as speech output.

We will investigate the possibility of compiler or operating system vendors bundling wxWindows with their product.

The high-level goal of wxWindows is to be thought of as the number one C++ framework, for virtually any platform. Move over, MFC!

What about Java?

The Java honeymoon period is over :-) and people are realising that it cannot meet all their cross-platform development needs. We don't anticipate a major threat from Java, and the level of interest in wxWindows is as high as ever.

How can I help the project?

Please check out the Backroom pages, in particular the suggested projects, and mail Julian Smart or the developers' mailing list with your own suggestions.