Features/GTK3/Porting/Implode

This page is being performed while I'm porting Implode Activity to Gtk3.

There is a ticket with some useful information that I'm using on the porting and to keep tracking this port. Besides, this wiki page will be useful to write some code snippets about what are the difficulties that I'm having on the port and maybe can be useful for someone else.

I will take this guide as reference on the Gtk3 porting.

Porting Gtk.DrawingArea

There are some things related with gtk.DrawingArea that we have to change when we are porting an activity to Gtk3. The names of the signals change and the way that they work as well.

Get allocation size

self.allocation property is no longer available and we should use self.get_allocation_width to get the allocation size:

self.allocation.width
self.allocation.height

should be replaced by:

self.get_allocated_width()
self.get_allocated_height()

Signals

expose-event

This signal was override by draw and it have to be connected with the method that was connected with the expose-event before. The method itself does not change but the arguments that it receives do. This is the new definition of the function in my case:

def _draw_event_cb(self, widget, cr):

size-allocate

This signal was used to resize the gtk.DrawingArea every time the window grows and at the startup of the activity. This is useful to re-draw the widget for different resolutions (desktops and XOs for example).

I used the same function connected to this signal but I change the signal connected by configure-event. Here is the definition of the callback:

def _configure_event_cb(self, widget, event):

I just used the size-allocate signal to save the the dimensions of the widget (width and height), so I can use them later on the draw signal.

def _size_allocate_cb(self, widget, rect):
    self.width = rect.width
    self.height = rect.height

Focus

Implode defines a new widget called GridWidget and it should be focusable because we want to move a cursor with the key arrows on it. So, this widget was using:

self.set_flags(Gtk.CAN_FOCUS)

but that method (set_flags) is no longer available and we have to replace it by:

self.set_can_focus(True)

Another thing related with the focus is to know who has the actual focus. In gtk2 it was done by

.focus_child

and in Gtk3 it should be replaced by:

.get_focus_child()

Handling .svg with rsvg

rsvg is a library to manage .svg files. The only thing that I found that should be updated is the import and the loading of a rsvg from data.

Replace the usual import:

import rsgv

by the Gtk3 one:

from gi.repository import Rsvg

This way to load a rsvg from data should be replaced:

rsvg.Handle(data=data)

by this new way

Rsvg.Handle.new_from_data(data)

Invalidate rectangle

Gdk.Window.invalidate_rect takes a Gdk.Rectangle instead a tuple in Gtk3.

rect = Gdk.Rectangle()
rect.x, rect.y, rect.width, rect.height = (0, 0, width, height)

self.get_window().invalidate_rect(rect, True)

Useful Links

• http://developer.gnome.org/gtk3/3.5/GtkWidget.html#GtkWidget-draw
• http://developer.gnome.org/gtk3/3.5/GtkWidget.html#GtkWidget-configure-event
• http://developer.gnome.org/rsvg/stable/
• http://developer.gnome.org/gdk3/stable/gdk3-Windows.html#gdk-window-invalidate-rect
• http://developer.gnome.org/gtk3/3.5/GtkWidget.html#gtk-widget-get-allocated-width