From 66266922ca742d38151bcc165f8f317e890ef85c Mon Sep 17 00:00:00 2001 From: Robert Roebling Date: Sun, 14 Nov 2004 21:52:55 +0000 Subject: [PATCH] The wxGNOME whitepaper-to-be. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@30523 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 --- docs/gtk/wxGNOME/wxGNOME.html | 164 ++++++++++++++++++++++++++++++++++ 1 file changed, 164 insertions(+) create mode 100644 docs/gtk/wxGNOME/wxGNOME.html diff --git a/docs/gtk/wxGNOME/wxGNOME.html b/docs/gtk/wxGNOME/wxGNOME.html new file mode 100644 index 0000000000..f8ad9851f1 --- /dev/null +++ b/docs/gtk/wxGNOME/wxGNOME.html @@ -0,0 +1,164 @@ + + + + + + + + + + +

Whitepaper: wxWidgets on the GNOME desktop

Introduction

wxWidgets^[1] +(formely known as wxWindows) is a C++ cross-platform GUI library, +whose distintive feature is the use of native calls and native +widgets on the respective platform, i.e. an application compiled for +the Linux platform will use the GTK+^[2] +library for displaying the various widgets. There is also a version +(„port“) of wxWidgets which uses the Motif toolkit for +displaying its widgets (this port is commonly referred to as wxMotif) +and another one, which only uses X11 calls and which draws its +widgets entirely itself, without using any outside library. This port +is called wxX11 or sometimes more generally wxUniv (short for +wxUniversal), since this widget set (implemented entirely within +wxWidgets) is available whereever wxWidgets is available. Since this +short overview is mainly about how to write wxWidgets applications +for the GNOME^[3] +desktop, I will focus on the GTK+ port, which is generally referred +to as wxGTK. +

wxGTK still supports the old version GTK+ 1.2, but it now defaults +to the uptodate version GTK+ 2.X, which is the basis for the current +GNOME desktop. By way of using GTK+ 2.X and its underlying text +rendering library Pango^[4], +wxGTK fully supports the Unicode character set and it can render text +in any language and script, that is supported by Pango.

wxWidgets' +design principles sofar

The three main design goals of the wxWidgets library are +portability across the supported platforms, complete integration with +the supported platforms and a broad range of functionality covering +most aspects of GUI and non-GUI application programming. Sometimes, +various aspects of these design goals contradict each other and this +holds true especially for the Linux platform which – from the +point of view of the desktop environment integration – is +lagging behind the other two major desktops (Windows and MacOS X) +mostly because of the schism between the GTK+ based GNOME desktop and +the Qt^[5] based +KDE^[6] desktop. So far, +the typical wxWidgets user targeted Windows, maybe MacOS X and Linux +in general, so the aim was to make wxGTK applications run as +well as possible on as many versions of Linux as possible, including +those using the KDE environment. Luckily, most of these distributions +included the GTK+ library (for running applications like the GIMP, +GAIM, Evolution or Mozilla) whereas the GNOME libraries were not +always installed by default. Also, the GNOME libraries didn't really +offer substantial value so that the hassle of installing them was +hardly justified. Therefore, much effort was spent on making wxGTK +fully functional without relying on the GNOME libraries, mostly by +reimplementing as much as sensible of the missing functionality. This +included a usable file selection dialog, a printing system for +PostScript output, code for querying MIME-types and file-icon +associations, classes for storing application preferences and +configurations, the possibility to display mini-apps in the taskbar, +a full-featured HTML based help system etc. With all that in place +you can write a pretty fully featured wxWidgets application on an +old Linux system with little more installed than X11 and GTK+.

Recent +developments

Recently, several key issues have been addressed by the GNOME +project. Sometimes integrated into the newest GTK+ releases (such as +the file selecter), sometimes as part of the GNOME libraries (such as +the new printing system with Pango integration or the mime-types +handling in gnome-vfs), sometimes as outside projects (such as the +media/video backend based on the Gstreamer^[7] +project). Also, care has been taken to unify the look and feel of +GNOME applications by writing down a number of rules (modestly called +„Human Interface Guidelines“^[8]) +and more and more decisions are taken in a desktop neutral way (for +both GNOME and KDE), mostly as part of the FreeDesktop^[9] +initiative. This development together with the rising number of +OpenSource projects using wxWidgets mainly for the Linux and more +specifically GNOME desktop has led to a change of direction within +the wxWidgets project, now working on making more use of GNOME +features when present. The general idea is to call the various GNOME +libraries if they are present and to offer a reasonable fallback if +not. I'll detail on the various methods chosen below:

Printing +system

The old printing system ....

MIME-type +handling

The old mime-type system used to simply query some files stored in +„typical“ locations for the respective desktop +environment. Since both the format and the location of these files +changed rather frequently, this system was never fully working as +desired for reading the MIME-types and it never worked at all for +writing MIME-types or icon/file associations. ...

The +new file dialog

Previously, wxGTK application made use of a file dialog written in +wxWidgets itself, since the default GTK+ file dialog was simplistic +to say the least. This has changed with version GTK+ 2.4, where a +nice and powerful dialog has been added. We now query the GTK+ +library, if the new file dialog functions are available and wxGTK +applications will show and use them if that is the case, otherwise, +they will fall back to the old generic one.

File +configuration and preferences

The usual Unix way of saving file configuration and preferences is +to write and read a so called „dot-file“, basically a +text file in a user's home directory starting with a dot. This was +deemed insufficient by the GNOME desktop project and therefore they +introduced the so called GConf system, for storing and retrieving +application and sessions information....

Results +and discussion

One of wxWidgets' greatest merits is the ability to write an +application that not only runs on different operating systems but +especially under Linux even on rather old systems with only a minimal +set of libraries installed – using a single application binary. +This was possible since most of the relevant functionality was either +located in the only required library (GTK+) or was implemented within +wxWidgets. Recent development outside the actual GTK+ project has +made it necessary to rethink this design and make use of other +projects' features in order to stay uptodate with current +techological trends. Therefore, a system was implemented within +wxWidgets that queries the system at runtime about various libraries +and makes use of their features whenever possible, but falls back to +a reasonable solution if not. The result is that you can create and +distribute application binaries that run on old Linux systems and +integrate fully with modern desktops, if they are available. This is +not currently possible with any other software.

About +the author

Robert Roebling works as a medical doctor in the Department of +Neurology at the University clinic of Ulm in Germany. He has studied +Computer Sciences for a few semesters and is involved in the +wxWidgets projects since about 1996. He has started and written most +of wxGTK port (beginning with GTK+ around 0.9) and has contributed to +quite a number projects within wxWidgets, ranging from the image +classes to Unicode support to making both the Windows and the GTK+ +ports work on embedded platform (mostly PDAs). He is happily married, +has two children and never has time.

Links +and citations

[1] See the wxWidgets homepage at www.wxwidgets.org.
[2] +See the GTK+ homepage at www.gtk.org.
[3] +See more about GNOME at www.gnome.org, +www.gnomedesktop.org, +www.gnomejournal.org, +www.gnomefiles.org.
[4] +See the Pango homepage at www.pango.org.
[5] +See the Qt homepage at www.trolltech.com.
[6] +See the KDE homepage at www.kde.org.
[7] +See Gstreamer homepage at gstreamer.freedesktop.org.
[8] +See GNOME's Human Interface Guidelines at +developer.gnome.org/projects/gup/hig.
[9] +See FreeDesktop's homepage at www.freedesktop.org.

+

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