[Sugar-devel] Object Chooser (selecting user-created audio objects from the Journal)

[Aleksey Lim]

On Tue, Dec 21, 2010 at 09:54:24PM -0500, Art Hunkins wrote:
> I'd like to thank all those who helped me get Object Chooser in the Journal 
> up and running in my FileMix activity. I'd also like to share my results, in 
> case the code could be helpful to others.
> 
> Excerpts follow:
> 
> from sugar.graphics.objectchooser import ObjectChooser
> from sugar import mime
> 
>    self.jname1 = "0"
>    self.jobject1 = 0
> 
>    if os.path.exists("/etc/fedora-release"):
>      release = open("/etc/fedora-release").read()
>      if release.find("OLPC release 9 ") == -1:
> # Insert here code relevent to Sugar 0.84 and higher
> # I use this to only display Object Chooser callback buttons only for >= 
> 0.84
> # Clicking one of the displayed buttons calls the choose1 method
> 
>  def choose1(self, widget):
>   chooser =  ObjectChooser(parent=self, what_filter=mime.GENERIC_TYPE_AUDIO)
>   result = chooser.run()
>   if result == gtk.RESPONSE_ACCEPT:
>     jobject = chooser.get_selected_object()
>     if jobject and jobject.file_path:
>       self.jobject1 = jobject
>       self.jname1 = str(jobject.get_file_path())
>   else:
>     self.jname1 = "0"
> 
> 
> Random observations:
> 
> 1) I exclude Sugar 0.82 for two reasons (which means, unfortunately, "no 
> user soundfiles for 0.82"):

Another useful way to check sugar version is:

    try:
        from jarabe import config
        version = [int(i) for i in config.version.split('.')][:2]
    except ImportError:
        version = [0, 82]

    if version >= [0, 84]:
        ...

>  a) its version of Object Chooser does not allow filtering for the audio 
> mime type;
>  b) Sugar 0.82's Csound (5.08) - or more specifically its version of 
> libsndfile - does not handle ogg vorbis soundfiles, the type that the Record 
> activity creates. Record is the most likely/accessible means that children 
> would use to create their own soundfiles. (The whole idea behind using 
> Object Chooser here is to select user files that have been placed in the 
> Journal [as Record does by default] for performance in FileMix.)
>  c) In addition, earlier versions of Record (<v64 or so) create ogg SPEEX 
> soundfiles; even the recent versions of Csound (actually, libsndfile) do not 
> handle this (lo-fi) format.
> 
> I found that a search for "OLPC release 9 " in /etc/fedora-release 
> identifies all current 0.82 incarnations of Sugar of which I'm aware.
> 
> 2) jname1 stores the soundfile name (complete path); jobject1 stores the 
> object itself. This is key to being able (in Csound) to locate and load the 
> selected soundfile. jname1 is then a channel opened to send the named 
> soundfile to Csound.

You can make code more elegant by using only jobject1
(and None initializer):

    self.jobject1 = None
    ...
    if result == gtk.RESPONSE_ACCEPT:
        ...
        self.jobject1 = jobject
    ...

    if self.jobject1 is not None:
        path = str(self.jobject1.get_file_path())
        ...

> 3) If the user closes the Object Chooser box instead of clicking on a sound 
> object, the result is not accepted, and jname1 reverts to "0" - which is a 
> flag (in Csound) to revert to the default soundfile included in FileMix.
> 
> 4) The str() cast for self.jname1 converts the filename to the usual path 
> format readable by Csound (this too is required).

Yeah, I guess it is dbus string object... maybe we need to this type
cast in sugar-toolkit code (though in most cases this casting should
happen implicitly).

> 
> Art Hunkins 
> 
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> 

-- 
Aleksey