This is needed to support matrix. Otherwise, getting
a matrix would remove the rows envelopess, which would
make the "cast" fails, since it would not know if the
internal rows are ValueArray or ValueList. I think reading,
modifying and setting back the matrix is an important use
case.
This patch adds overrides to support IntRange, Int64Range, DoubleRange,
FractionRange, Array and List. For integer ranges, it maps this
to python 'range'. Gst.IntRange() and Gst.Int64Range() are simple cast
to let the underlying code know which GType to use. To set such range in
python you will do:
structure["range"] = Gst.IntRange(range(0,10,2)))
Same for the 64 bit variant. And when you do:
r = structure.get_value("range")
A range will be returned directly, without the wrapper. For DoubleRange
and FractionRange, there is no native support in python. So the usage
will be:
structure["range"] = Gst.DoubleRange(0,10.0)
structure["range"] =
Gst.FractionRange(Gst.Fraction(1/30), Gst.Fraction(1/5)
When getting this value, Gst.DoubleRange and Gst.FractionRange class are
returned. They both have start/stop members. The naming was taken from
range type.
For Array and List, both uses the native list type, though they can be
constructed from any python sequence. So again, the class is just like
a cast, to let it pick the right GType and python list are being
returned.
structure["list"] = Gst.ValueList([1,2,3,4])
structure["array"] = Gst.ValueArray([1,2,3,4)
Using string and tuple could also work. Since Gst.ValueList/Array are
sequence, you can convert one to the other with:
list = Gst.ValueList([1,2,3,4])
array = Gst.ValueArray (list)
https://bugzilla.gnome.org/show_bug.cgi?id=753754
