The document discusses the porting of Eclipse's SWT GUI toolkit to GTK+ 3. It describes the motivation for porting to the newer version of GTK+, the challenges in doing so, and the solutions developed. It also outlines future plans, including supporting Wayland, HTML5/web-based interfaces, and preparing for GTK+ 4.

1. Arun Thondapu
Eclipse SWT Project Co-Lead
Equinox (Launcher) Committer
IBM
arunkumar.thondapu@in.ibm.com
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2.  Motivation
 Evolution of GTK+
 Porting SWT to GTK+ 3
 Challenges
 Solutions
 Collaboration
 WIP
 What’s Next ??
 Wayland support
 Broadway, HTML 5
 GTK+ 4
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3.  Linux vs Others
 Significant changes in underlying windowing system (GTK+)
 Separate API and ABI incompatible streams
 How to be on the “bleeding edge”
 Need parallel streams of development and maintenance
 Open and diverse nature of Linux distributions = support for a large range of GTK+
versions
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"GTK+ software architecture" by Shmuel Csaba Otto Traian. Licensed under CC BY-SA 4.0 via Wikimedia Commons -
http://commons.wikimedia.org/wiki/File:GTK%2B_software_architecture.svg#mediaviewer/File:GTK%2B_software_architecture.svg

5.  Originally designed and used in the GNU Image Manipulation Program (GIMP) as
a replacement of the Motif toolkit.
 GTK+ 2.0
 improved text rendering using Pango
 a new theme engine
 improved accessibility using ATK
 complete transition to Unicode using UTF-8 strings
 more flexible API and new widgets
 usage of Cairo graphics library for rendering vector graphics (since version 2.8)
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6.  GTK+ 3
 cairo drawing throughout, GDK no longer wraps the antiquated X11 drawing API
 modern input device handling via XInput2
 new theming API with CSS syntax for theme configuration and animations
 multiple backend support for GDK (including experimental support for Wayland and
HTML5)
 integration of D-Bus support in GIO
 use GIO for launching applications
 new widgets, such as a switch and an application chooser
 improved support for touch and gestures
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7.  Primary goal was a seamless user experience on a wide variety of Linux versions
irrespective of underlying versions of GTK+ shipped by them.
 to be as backward compatible as possible
 in contrast to most native GTK+ apps including GNOME
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libgtk-x11-2.0.so.0
libswt-pi-gtk-****.so libswt-pi3-gtk-****.so
libgtk-3.so.0

8.  Do not include individual headers
 Do not use deprecated symbols
 Use accessor functions instead of direct access
 Replace GDK_<keyname> with GDK_KEY_<keyname>
 Use GIO for launching applications instead of the gdk_spawn family of functions
 Use cairo for drawing
 GdkGC and GdkImage are removed
 gdk_draw family of functions are gone
 GtkWidget “expose-event” signal has been replaced by a new “draw” signal
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9.  The modern GTK+ drawing model
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10.  Many great and diverse contributions
from community (led by Red Hat
team) towards the GTK+ 3 port
 Much more stable and usable now
 Please continue to test, report bugs
and contribute patches!
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11.  Working on resolving most major outstanding problems before Mars
 Bugzilla summary tags – GTK3, GTK 3.10
 Lots more stuff being deprecated and replaced by GTK+
 GdkColor is being replaced by GdkRGBA
 Many enhancements as well but we may not be able to adopt right now, stability is
the major concern
 Lack of backwards-compatibility in major updates continues to be an issue
 Can we aggressively drop support for older versions of GTK+ 2.x?
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12.  Mars drops support for GTK+ < 2.18
 How to find out which version of GTK+ is being used by my Eclipse or SWT
application?
 Use the Java property org.eclipse.swt.internal.gtk.version
 Prevent linking against GTK+ 2.x and GTK+ 3.x in the same process
 Leads to unexpected hangs or hard-to-diagnose crashes
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13.  Eclipse Mars
 GTK+ 3 always (assuming it is installed and available)
 Eclipse Luna, SR1 & SR2
 GTK+ < 3.10 => GTK3
 GTK+ >= 3.10 => GTK2
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14.  Webkit is embedded by default on Linux but XULRunner is also supported
 libwebkitgtk-1.0-0 vs. libwebkitgtk-3.0-0
 libwebkitgtk-1.0-0 is not installed by default on some distros => Luna and
earlier do not have an active browser in Eclipse!
 libwebkit2gtk-3.0-25 vs. libwebkit2gtk-4.0-37
 XULRunner does not have a GTK+ 3 port yet…
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15.  Wayland is intended as a simpler replacement for X, easier to develop and
maintain.
 Origins in initial effort towards X12.
 Hardware and applications are constantly evolving, X11 extensions are unable to
fill in the gaps anymore.
 Design and build a new display server from scratch focusing on modern platforms.
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16.  Wayland is a display protocol for a compositor to talk to its clients as well as a C
library implementation of that protocol.
 Weston reference implementation is the only Wayland compositor as of now.
 Eliminates needless complexity and improves performance compared to X11.
 Smaller footprint.
 Designed to work well with non-PC interfaces (embedded devices, tablets and phones).
 Shipped on a number of embedded products, phones, and tablets.
 For the desktop, GNOME and KDE ports to Wayland (and of course the protocol
itself) are currently WIP.
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20. • Rudimentary support available at
this stage
• Google Summer of Code 2014
project by Joshua Barkovic
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21.  GDK Broadway backend provides support for displaying GTK+ applications in a
web browser, using HTML5 and web sockets.
 GDK_BACKEND = broadway
 http://127.0.0.1:8080
 Works only with GTK3
 Use multiple GTK+ applications in the same web browser window, by using the
Broadway server, broadwayd, that ships with GTK+.
 broadwayd :5
 BROADWAY_DISPLAY - Specifies the Broadway display number.
 BROADWAY_DISPLAY=:5 gedit
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23.  Can SWT itself use web (HTML5) based elements to build the UI of the application
instead of the OS's native widgets?
 Eclipse running inside a web browser?
 Allows CSS customization of UI.
 Eclipse integration with Orion and Flux in a browser.
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24.  Animations
 Effects
 Transformations
 Event bubbling
 No more GDK windows
 Multimedia
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 Scene graph
 Improved CSS support
 Better cross-platform story
 Better support for application
development
 Touch and gesture support
 Focus on HIG

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26. “GTK+ 4 shall be as
rock-stable (and
hence "boring") as
GTK+ 2”
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