As a side-effect, this also now includes the element factory name in the
error messages instead of giving the same error string for every
factory.
Partially fixes https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/issues/318
Also let them all go through the same, single object construction code.
... in function signatures.
These breaking changes aim at improving usability by allowing users
to take advantage of Rust error management features sur as `ok_or`,
`map_err`, `expect` and the `?` operator. See the `examples` and
`tutorials` to get an idea of the impacts.
Allow instantiating and dereferencing concrete queries. The motivation
for this proposal is to allow the following usability enhancements:
- Concrete queries mutability guaranteed by the borrow checker,
including for generic functions:
``` rust
let mut p = Query::new_position(::Format::Time);
p.get_mut_structure().set("check_mut", &true);
```
- Concrete queries functions available in place:
``` rust
let mut q = gst::Query::new_duration(gst::Format::Time);
let duration = if pipeline.query(&mut q) {
Some(q.get_result())
} else {
None
};
```
FormatValue is now renamed to GenericFormattedValue and the API slightly
changed. In addition there is now a FormattedValue trait, and a
SpecificFormattedValue trait plus types for Bytes, Buffers and the
existing ClockTime.
This allows to create functions like
Pad::query_duration<F: SpecificFormattedValue>() -> Option<F>
and doesn't require the caller to unwrap the generic value anymore,
which is completely unneeded in these cases.
In addition, Segment became FormattedSegment<T> with API to
upcast/downcast between the specific formatted values and the generic
formatted value. This greatly simplifies usage of Segments.
There's now get_result() instead of get(), and separate getters for only
getting the constructor arguments of each query (otherwise query
handlers will get useless values when trying to answer a query).
And also implement a FormatValue type that holds a value together with
its format to make usage of the positions/durations/seek positions/etc
more convenient and safe.
Fixes https://github.com/sdroege/gstreamer-rs/issues/3
