‍Compositor-plugin SDK for Phosphor. Provides the interface contract, D-Bus client, and shared utilities a compositor plugin needs to give its users zone-based window management.

Responsibility

Phosphor splits into a daemon (owns placement logic, zones, layouts, settings) and a compositor plugin (observes windows, applies geometry, renders overlays). This library is the plugin side of that split.

A compositor plugin links PhosphorCompositor, implements ICompositorBridge (23 methods mapping native window handles to the daemon's vocabulary), wires handler interfaces for callbacks, and lets DaemonClient manage all D-Bus communication. The plugin never touches placement logic directly. The daemon decides where, and the plugin applies how.

Key types

Type	Purpose
`ICompositorBridge`	Abstract interface a plugin implements for window lookup, identity, properties, filtering, actions
`DaemonClient`	Typed D-Bus client handling registration, service watching, reconnection, method calls, signal dispatch
`IDragHandler`	Callback interface for drag start/move/end/policy-change
`IGeometryHandler`	Callback interface for geometry apply, batch operations, raise/activate
`ILifecycleHandler`	Callback interface for window open/close/activate/float-change
`BorderState` + `AutotileStateHelpers`	Per-screen border-state value type plus pure helper functions
`FloatingCache`	Compositor-side mirror of daemon float state
`SnapAssistFilter`	Snap-assist candidate building via bridge
`TriggerParser`	Modifier/button activation matching from config
`DebouncedScreenAction`	Debounce utility for screen-change coalescing
`GeometryHelpers`	Fractional-scaling-safe rounding

Typical use

#include <PhosphorCompositor/DaemonClient.h>
#include <PhosphorCompositor/ICompositorBridge.h>
#include <PhosphorCompositor/IGeometryHandler.h>

class MyBridge : public PhosphorCompositor::ICompositorBridge { /* ... */ };

class MyPlugin : public PhosphorCompositor::IGeometryHandler,
                 public PhosphorCompositor::IDragHandler,
                 public PhosphorCompositor::ILifecycleHandler
{
    PhosphorCompositor::DaemonClient m_client;
    MyBridge m_bridge;

    void init() {
        m_client.setGeometryHandler(this);
        m_client.setDragHandler(this);
        m_client.setLifecycleHandler(this);

        connect(&m_client, &PhosphorCompositor::DaemonClient::daemonReady,
                this, [this]() {
            m_client.registerBridge("river", 3, {"borderless", "animation"});
        });
    }

    // IGeometryHandler
    void onApplyGeometry(const PhosphorCompositor::GeometryRequest& req) override {
        auto* window = m_bridge.findWindowById(req.windowId);
        if (window) m_bridge.moveResize(window, req.geometry);
    }
    // ... other handlers
};

Existing adapters

Compositor	Adapter	Location
KWin 6	`KWinCompositorBridge`	`kwin-effect/kwin_compositor_bridge.{h,cpp}`
river	planned	—

Architecture

Daemon (org.plasmazones D-Bus service)
    ↕ D-Bus IPC
DaemonClient (this library)
    ↓ dispatches to
IDragHandler / IGeometryHandler / ILifecycleHandler
    ↓ implemented by
Compositor Plugin
    ↓ calls
ICompositorBridge (plugin implements, wraps native window APIs)

The daemon always runs. The plugin is stateless with respect to placement. It applies what the daemon tells it and reports window events back.

Dependencies

Qt6::Core, Qt6::Gui, Qt6::DBus
`phosphor-protocol`, `phosphor-identity`, `phosphor-animation`

Phosphor Qt6 / Wayland library suite for window-management tools