Struct gstreamer_base::FlowCombiner

pub struct FlowCombiner(_);

Utility struct to help handling gst::FlowReturn combination. Useful for gst::Elements that have multiple source pads and need to combine the different gst::FlowReturn for those pads.

FlowCombiner works by using the last gst::FlowReturn for all gst::Pad it has in its list and computes the combined return value and provides it to the caller.

To add a new pad to the FlowCombiner use FlowCombiner::add_pad. The new gst::Pad is stored with a default value of gst::FlowReturn::Ok.

In case you want a gst::Pad to be removed, use FlowCombiner::remove_pad.

Please be aware that this struct isn't thread safe as its designed to be used by demuxers, those usually will have a single thread operating it.

These functions will take refs on the passed gst::Pads.

Aside from reducing the user's code size, the main advantage of using this helper struct is to follow the standard rules for gst::FlowReturn combination. These rules are:

• gst::FlowReturn::Eos: only if all returns are EOS too
• gst::FlowReturn::NotLinked: only if all returns are NOT_LINKED too
• gst::FlowReturn::Error or below: if at least one returns an error return
• gst::FlowReturn::NotNegotiated: if at least one returns a not-negotiated return
• gst::FlowReturn::Flushing: if at least one returns flushing
• gst::FlowReturn::Ok: otherwise

gst::FlowReturn::Error or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are returned immediatelly from the FlowCombiner::update_flow function.

Methods

impl FlowCombiner

pub fn new() -> FlowCombiner

Creates a new FlowCombiner, use FlowCombiner::free to free it.

Returns

A new FlowCombiner

pub fn add_pad<P: IsA<Pad>>(&self, pad: &P)

Adds a new gst::Pad to the FlowCombiner.

pad

the gst::Pad that is being added

pub fn clear(&self)

Removes all pads from a FlowCombiner and resets it to its initial state.

pub fn remove_pad<P: IsA<Pad>>(&self, pad: &P)

Removes a gst::Pad from the FlowCombiner.

pad

the gst::Pad to remove

pub fn reset(&self)

Reset flow combiner and all pads to their initial state without removing pads.

pub fn update_flow(&self, fret: FlowReturn) -> FlowReturn

Computes the combined flow return for the pads in it.

The gst::FlowReturn parameter should be the last flow return update for a pad in this FlowCombiner. It will use this value to be able to shortcut some combinations and avoid looking over all pads again. e.g. The last combined return is the same as the latest obtained gst::FlowReturn.

fret

the latest gst::FlowReturn received for a pad in this FlowCombiner

Returns

The combined gst::FlowReturn

pub fn update_pad_flow<P: IsA<Pad>>(     &self,     pad: &P,     fret: FlowReturn ) -> FlowReturn

Sets the provided pad's last flow return to provided value and computes the combined flow return for the pads in it.

The gst::FlowReturn parameter should be the last flow return update for a pad in this FlowCombiner. It will use this value to be able to shortcut some combinations and avoid looking over all pads again. e.g. The last combined return is the same as the latest obtained gst::FlowReturn.

pad

the gst::Pad whose gst::FlowReturn to update

fret

the latest gst::FlowReturn received for a pad in this FlowCombiner

Returns

The combined gst::FlowReturn

Trait Implementations

impl Clone for FlowCombiner

fn clone(&self) -> FlowCombiner

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl StaticType for FlowCombiner

fn static_type() -> Type

Returns the type identifier of Self.

impl Default for FlowCombiner

fn default() -> Self

Returns the "default value" for a type.