wiki:HackingGtk

Version 1 (modified by alp@atoker.com, 14 years ago) (diff)

Add GTK+ hacking information verbatim

Hacker's guide to WebKit/GTK+

Code layout

The GTK+ port targets the cross-platform GLib and GTK+ APIs. This means that it can be built against any of the windowing systems supported by GTK+ and Cairo without modification -- those tested so far are X11 and DirectFB. Windows should work too, possibly needing a couple of tweaks.

This means that developers adding code specific to a certain windowing system should make sure their changes are conditionally compiled only when that windowing system is available. This might be done at configure time or with a switch passed to the build system, or even just using the definitions provided by the gdk headers.

The main components of the port:

Gtk+-specific modules

There may be other gtk-port related directories which have yet to be listed here.

Shared code modules

While the Gtk+ port is the primary consumer of these backends, we aim to keep them portable, avoiding even ifdef'd sections specific to the Gtk+ port:

Current tasks (July '07)

  • Make things work with debugging enabled (when NDEBUG is removed, assertions are triggered right now)
  • Fix animated GIF images -- consider using GdkPixbuf?
  • Continue to fix the curl backend
  • Start to consider consolidating the widget into a single place as the Qt port has done, and look into implementing eg. createFrame()
  • Look into supporting the canvas
  • Attempt to merge the Cairo code in the Win32 port -- the equivalent code is copy-and-pasted into the "Gdk" port in some places. This will help reduce code duplication but also help towards getting WebKit/Gdk/Gtk+ working on Windows

Issues known

CURL

  • Review and possibly integrate the sand-labs CURL backend code. It has a slightly different API, so needs to be back-ported, but looks like it may be more feature-complete, able to handle redirects properly etc.
  • The non zero select timeout feels bad. Make it possible to write a GSourceFunc to not poll the sockets and have a timeout: This can probably be done by integrating code from MIT/X11 licensed glibcurl.
  • Cookie handling is completely lacking as pointed out on the mailing list
  • Errors of curl need to be properly populated

Gtk

  • A lot of classes are not yet implemented
  • For painting we have some issues in regard to Expose Events and when WebKit will call paint.

Theming

  • Consider taking code directly from Mozilla's LGPL licensed Gtk+ theming backend. They deal with a lot of corner cases which don't look fun to re-implement.
  • Focus ring drawing
  • Scrollbars for PlatformScrollbar will be terrible as we need to implement a HitTest but don't know where the elements of the scrollbar hide
  • Native theming for text entries
  • Find a way to draw a GtkComboBox, at least the button part. This is needed to implement theming of the <select> element properly.