Activity Team/Compatibility Tips

Compatibility Tips

SUGAR_BUNDLE_VERSION

Some earlier OLPC builds (e.g., 703) do not have a bundle version environment variable, so you need to catch an exception if you want to access the version.

try:
    version = os.environ['SUGAR_BUNDLE_VERSION']
except:
    version = "unknown"

get_activity_root()

Some earlier OLPC builds (e.g., 656) do not have activity.get_activity_root(), so you need to catch an exception if you want to access the version.

try:
    path = activity.get_activity_root()
except:
    # early versions of Sugar (656) didn't support get_activity_root()
    path = "/home/olpc/.sugar/default/[your activity bundle id as specified in activity.info]"

e.g.,

    path = "/home/olpc/.sugar/default/org.laptop.TurtleArtActivity"

SVG

Some earlier OLPC builds (e.g., 656) use an older version of the gtk svg libraries that don't process svg files that use the <svg:tag> syntax. It seems that removing svg: resolves the rendering problem.

<svg:path> won't work
<path> will work

Another issue is with SVG paths. Some SVG editors, e.g., inkscape, sometimes omit the l in a path that uses relative line-tos. These paths will not render properly on old OLPC builds.

<path d="m 100,100 10,10 /> won't work
<path d="m 100,100 l 10,10 /> will work

In recent Fedora/Sugar builds (F13/0.88) another SVG problem has been occurring. If you define a path without explicitly defining stroke and fill colors, it will render as black, even if you define stroke and fill colors in your initial <svg> block.

<svg ... stroke="&stoke_color;" fill="&fill_color;" ... >
<path ... /> won't work
<path ... stroke="&stoke_color;" fill="&fill_color;" /> will work
</svg>

artwork

Some Sugar icons are not present in old systems. If, for example, you want to use the filesave icon, you should include a copy in your bundle (in the icon subdirectory) to ensure that it is present on older systems.

Q: Is there a comprehensive list somewhere of which icons were added to sugar-artwork when?

tool tips

Older versions of Sugar did not support tool tips. You could catch the exception as per:

try:
    self.activity.fullscreen_button.props.accelerator = '<Alt>Enter'
except AttributeError:
    pass

Note that this is only relevant to pre-0.86 toolbars.

screen size

The screen size varies on different hardware platforms. If you develop in an emulator, it is worthwhile trying different sizes to make sure your activity scales properly.

Some useful utilities:

width = gtk.gdk.screen_width()
height = gtk.gdk.screen_height()

toolbox = activity.ActivityToolbox(self)
toolboxheight = toolbox._activity_toolbar.size_request()[1]

import tarfile

At some point, the behavior of the Python tarfile library seems to have changed (I've not yet hunted down the documentation.) In any case, on Build 767, it was generating .tar suffixes and on later builds (newer Python libraries?) it was generating .gtar suffixes. I got burnt by this in Turtle Art so now I check for both.

if file_path.endswith(('.gtar', '.tar')):

Sugar toolbar version

Sugar toolbars changed in Sucrose v0.86. You can detect which version you are running by checking for an ImportError:

try:  # 0.86 toolbar widgets
   from sugar.activity.widgets import ActivityToolbarButton, StopButton
   from sugar.graphics.toolbarbox import ToolbarBox, ToolbarButton
   has_toolbarbox = True
except ImportError:
   has_toolbarbox = False

Use the flag to determine whether to create old-style or new toolbars:

if has_toolbarbox:
    # Use 0.86+ toolbar design
    toolbar_box = ToolbarBox()
    ...
else:
    # Use pre-0.86 toolbar design
    self.toolbox = activity.ActivityToolbox(self)
    ...

You can share callbacks between versions, but take care to make sure you are using the proper context:

# 0.86+
fullscreen_button.connect('clicked', self._do_fullscreen_cb)

or

# pre-0.86
self.viewToolbar = ViewToolbar(self)
...

class ViewToolbar(gtk.Toolbar):
    def __init__(self, pc):
        self.activity = pc
        ...

        self.activity.fullscreen_button.connect('clicked', self.activity._do_fullscreen_cb)

Python versions

Some Sugar systems are running on older versions of Python. Take care to make sure you don't run into syntax errors do to changes in the Python language. For example, I was burned on the following:

   except Exception as e: # works fine with Python 2.6 but raises a syntax error with Python 2.5
   except Exception, e:   # works fine in both cases.

See python.org for more information on incompatibilities between versions.

GNOME toolkit versions

In older versions of gtk, e.g., 2.16.0, the set_size_request method does not work properly for label.

   label = gtk.Label(string)
   label.set_line_wrap(True)
   label.set_size_request(width, -1)

Works fine on 2.22.0

I'll try to track down the relevant gtk patch.