Phosphor::Screens::PlasmaPanelSource Class Reference

IPanelSource implementation that queries KDE Plasma Shell over D-Bus for panel-reservation offsets. More...

#include <phosphor-screens/include/PhosphorScreens/PlasmaPanelSource.h>

Inheritance diagram for Phosphor::Screens::PlasmaPanelSource:

Public Member Functions
	PlasmaPanelSource (QObject *parent=nullptr)
	~PlasmaPanelSource () override
void	start () override
	Begin watching.
void	stop () override
	Stop watching.
Offsets	currentOffsets (QScreen *screen) const override
	Snapshot for a given screen.
bool	ready () const override
	Has any successful query landed? Drives ScreenManager's panelGeometryReady one-shot signal — consumers that compute initial zone geometry at daemon startup gate on this so they don't lay out windows against the unreserved screen rect.
void	requestRequery (int delayMs=0) override
	Best-effort: ask the backend to re-query immediately, optionally after a short delay (e.g.
Public Member Functions inherited from Phosphor::Screens::IPanelSource
	IPanelSource (QObject *parent=nullptr)
	~IPanelSource () override=default

Additional Inherited Members
Signals inherited from Phosphor::Screens::IPanelSource
void	panelOffsetsChanged (QScreen *screen)
	Offsets for screen changed.
void	requeryCompleted ()
	A requestRequery cycle completed.

Detailed Description

IPanelSource implementation that queries KDE Plasma Shell over D-Bus for panel-reservation offsets.

Pure D-Bus client — links Qt6::DBus only, no KF6, no KDE Frameworks. Built into PhosphorScreens unconditionally; consumers on non-KDE desktops just wire a different IPanelSource (typically NoOpPanelSource).

Lifecycle:

• On start(), watches org.kde.plasmashell registration. Kicks off an initial async query immediately if the service is already on the bus, otherwise waits for the registration signal.
• Async D-Bus calls only — the GUI thread is never blocked.
• Per-screen offsets keyed by QScreen::name() (the connector name). Plasma's panel API exposes a screen INDEX which can disagree with Qt's screen list ordering on multi-monitor setups, so we match by screen geometry instead.

Coalescing: rapid requestRequery calls coalesce into a single in-flight D-Bus call. The watcher slot fires requeryCompleted exactly once per outstanding request after the reply lands.

Constructor & Destructor Documentation

PlasmaPanelSource()

Phosphor::Screens::PlasmaPanelSource::PlasmaPanelSource ( QObject *  parent = nullptr )

explicit

~PlasmaPanelSource()

Phosphor::Screens::PlasmaPanelSource::~PlasmaPanelSource ( )

override

Member Function Documentation

currentOffsets()

Offsets Phosphor::Screens::PlasmaPanelSource::currentOffsets ( QScreen *  screen ) const

overridevirtual

Snapshot for a given screen.

Returns zero offsets if the source has no information for this screen yet.

Implements Phosphor::Screens::IPanelSource.

ready()

bool Phosphor::Screens::PlasmaPanelSource::ready ( ) const

overridevirtual

Has any successful query landed? Drives ScreenManager's panelGeometryReady one-shot signal — consumers that compute initial zone geometry at daemon startup gate on this so they don't lay out windows against the unreserved screen rect.

Latch semantics: implementations MAY keep ready() returning true across stop / start cycles — the contract is "panels have been queried successfully at least once", not "a fresh query has completed since the last start". Consumers that need a liveness indicator should listen for requeryCompleted after their own requestRequery, rather than polling ready().

Implements Phosphor::Screens::IPanelSource.

requestRequery()

void Phosphor::Screens::PlasmaPanelSource::requestRequery ( int  delayMs = 0 )

overridevirtual

Best-effort: ask the backend to re-query immediately, optionally after a short delay (e.g.

to let a panel-editor UI close fully before settling). Implementations that don't support push-style refresh can no-op; requeryCompleted is still expected to fire at most once per call so callers can chain UI updates.

Implements Phosphor::Screens::IPanelSource.

start()

void Phosphor::Screens::PlasmaPanelSource::start ( )

overridevirtual

Begin watching.

Implementations may emit panelOffsetsChanged any time after this returns; ScreenManager reads currentOffsets on each emission to refresh its cache.

Implements Phosphor::Screens::IPanelSource.

stop()

void Phosphor::Screens::PlasmaPanelSource::stop ( )

overridevirtual

Stop watching.

Subsequent currentOffsets queries should still return the last-known values; only the change channel is closed.

Implements Phosphor::Screens::IPanelSource.

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The documentation for this class was generated from the following file:

• phosphor-screens/include/PhosphorScreens/PlasmaPanelSource.h