enricobuehler
bbd98241e4
A user-configurable policy layer above the per-compositor VirtualDisplay backends: keep-alive, topology, conflict, identity, layout, max-displays — persisted to display-settings.json, editable from the web console, applied per connect. Design: design/display-management.md. Stage 0 stands up the surface and wires the two behaviors the existing code can already express — the Windows monitor linger duration and the "make the streamed output the sole desktop" topology — through it; every other option is stored + echoed but not yet enforced (later stages). An unconfigured host (no display-settings.json) keeps today's exact behavior. - vdisplay/policy.rs: pure DisplayPolicy + 5 presets + JSON store (gpu-settings pattern) + EffectivePolicy; 9 unit tests. - vdisplay.rs: resolve_topology(Auto); apply_session_env drives *_VIRTUAL_PRIMARY from the policy only when a settings file exists. - windows/manager.rs: linger_ms() + should_isolate() read the policy when configured. - mgmt: GET/PUT /api/v1/display/settings (bearer-only); PUT rejects keep_alive forever until the lifecycle stage. OpenAPI regenerated. - web console: Host → Virtual displays card (preset picker + custom fields); en+de. - docs-site: virtual-displays.md + configuration.md cross-links. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
134 lines
7.6 KiB
Markdown
134 lines
7.6 KiB
Markdown
---
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title: Virtual displays
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description: Control how punktfunk creates, keeps alive, and arranges the virtual displays it streams — presets, keep-alive, exclusive vs. extend, and persistent per-client scaling.
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---
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When a client connects, punktfunk creates a **virtual display** sized to exactly that client's
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resolution and refresh, renders your desktop or game onto it, and streams it. This page is about the
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**policy** for that display: how long it survives a disconnect, whether it takes over your physical
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monitors, what happens when a second client connects, and how desktop environments remember
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per-client settings like scaling.
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You set this policy in the **web console** (Host → *Virtual displays*), or by editing
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`~/.config/punktfunk/display-settings.json` directly (`%ProgramData%\punktfunk\display-settings.json`
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on Windows). A change applies to the **next** connection — a running session keeps the display it
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opened on.
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> **You rarely need to touch this.** The default behavior matches how punktfunk has always worked.
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> Reach for a preset when you want a specific experience — a dedicated couch/gaming box, a desktop
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> you also use in person, or a multi-monitor workstation.
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> **What's live today:** this release wires **keep-alive** (linger duration) and **topology**
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> (extend / primary / exclusive). The other options below — conflict handling, identity/scaling
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> persistence on Linux, and multi-monitor layout — are **stored but not yet enforced**; they arrive
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> in following releases. The console marks them accordingly. Windows already persists per-client
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> scaling (see [Persistent scaling](#persistent-scaling)).
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## Pick a preset
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A preset is the easy way in — select one in the console and you're done. Each expands to a bundle of
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the individual options documented further down.
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| Preset | What it's for |
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| **Default** | Today's behavior. A short linger absorbs reconnects, the streamed output becomes the sole desktop, and extra clients each get their own view. |
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| **Gaming rig** | A dedicated couch/headless box. The game and its display survive disconnects indefinitely, and whoever connects takes the box over. *(Arrives with the keep-alive stage.)* |
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| **Shared desktop** | A desktop you also use in person. punktfunk never blanks your real monitors and never leaves a ghost display behind; concurrent viewers each get a view. |
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| **Hot-desk** | One user at a time with fast reattach — roaming between your own devices. A second user is told the box is busy, and each device+resolution keeps its own scaling. |
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| **Workstation** | The multi-monitor daily driver. Your displays come back exactly where you arranged them, with per-client identity and an exclusive desktop. |
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## Options reference
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Choose **Custom** in the console to set these directly.
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### Keep alive
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How long the virtual display survives after your last session disconnects. On a gamescope game host,
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this also keeps the **game itself running** so you can reconnect straight back into it.
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- **Off** — tear the display down at session end (nothing lingers).
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- **A duration** (seconds) — keep it for that long; a reconnect inside the window drops you straight
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back in, with no re-negotiation and no desktop reshuffle.
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- **Forever** — keep it until you stop the host or release it from the console. *(Arrives with the
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keep-alive lifecycle stage; the console won't let you save it before then.)*
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Default: **10 seconds**. Windows has always lingered 10 s; the Linux backends previously tore down
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immediately — a short linger makes reconnects smoother on both.
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> **Keep-alive + Exclusive keeps your physical monitors dark after you disconnect**, until the
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> linger expires or you release the display. That's intentional for a dedicated gaming box, but
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> don't set a long/forever keep-alive together with Exclusive on a machine whose monitors you also
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> use in person — use **Shared desktop** there instead.
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### Topology
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What punktfunk does with your monitor layout while it streams.
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- **Extend** — add the virtual display alongside your real monitors; touch nothing else.
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- **Primary** — make the virtual display your primary output; your physical monitors stay on.
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- **Exclusive** — the virtual display becomes your **only** enabled output (physical monitors are
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disabled, then restored when streaming ends). This is what makes the streamed surface *be* the
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desktop, so panels and windows land on it.
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- **Automatic** *(default)* — Exclusive on Windows and on an auto-detected KDE/GNOME desktop
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("stream this desktop" means the streamed output *is* the desktop); Extend when you've pinned a
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specific compositor with `PUNKTFUNK_COMPOSITOR` (a test/CI posture).
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Per-backend support:
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| | KWin | Mutter/GNOME | Sway/wlroots | Windows |
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| Extend | ✅ | ✅ | ✅ | ✅ |
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| Primary | ✅ | ✅ | ⚠️ treated as Extend | ✅ *(following release)* |
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| Exclusive | ✅ | ✅ | ✅ *(following release)* | ✅ |
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### Conflict handling · identity · layout
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These are **stored but not yet enforced** — they're documented here so you know what's coming and
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can set them ahead of the release that turns them on:
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- **Conflict handling** — what happens when a *different* client connects while one is already
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streaming and asks for a different resolution: give it its own display (**separate**), take the
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box over (**steal**), share the existing display at its current mode (**join**), or refuse it
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(**reject**).
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- **Identity** — whether each client gets a **stable display identity** so your desktop environment
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remembers its settings (see below): one shared identity, one **per client**, or one **per client +
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resolution**.
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- **Layout / max displays** — how multiple virtual displays are arranged (for multi-monitor), and an
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upper bound on how many can be live at once.
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## Persistent scaling
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Set your display **scaling** once and have it stick across reconnects. This works by giving each
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client a *stable display identity*, so your desktop environment keys its per-monitor settings to it.
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| Host | Supported | How |
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| **Windows** | ✅ today | Connect, set scaling in Settings while streaming — Windows remembers it per client. |
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| **KDE / KWin** | ⏳ following release | A stable per-client output name lets KWin persist scale/mode per client. |
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| **GNOME / Mutter** | ❌ | GNOME's virtual-monitor API exposes no stable identity to key config on. |
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| **Sway / wlroots** | ❌ | Headless outputs can't carry a stable identity; pin scale in your sway config instead. |
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## Legacy environment knobs
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These `PUNKTFUNK_*` variables still work, but the console (and `display-settings.json`) supersede
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them — when a settings file exists, it wins.
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| Legacy knob | Now expressed as |
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| `PUNKTFUNK_MONITOR_LINGER_MS` | **Keep alive** → duration *(Windows)* |
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| `PUNKTFUNK_NO_ISOLATE` | **Topology** → Extend *(Windows)* |
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| `PUNKTFUNK_KWIN_VIRTUAL_PRIMARY` / `PUNKTFUNK_MUTTER_VIRTUAL_PRIMARY` | **Topology** → Exclusive (when set) / Extend (when `0`) |
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## Troubleshooting
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**My physical monitors stayed off after I disconnected.** You have keep-alive set together with
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Exclusive topology — the display (and your isolated desktop) is being kept for the linger window.
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Release it from the console (Host → *Virtual displays*), or switch to the **Shared desktop** preset
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so streaming never disables your real monitors.
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**The virtual output shows only my wallpaper.** Your topology is Extend, so the streamed display is
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an empty extension. Use **Primary** or **Exclusive** so your desktop actually lands on it.
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**KWin virtual outputs need KWin ≥ 6.5.6.** Older KWin can't create the virtual output at all —
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see [requirements](/docs/requirements).
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