88 lines
5.1 KiB
Markdown
88 lines
5.1 KiB
Markdown
# Desktop portals
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Applications call the standard `org.freedesktop.portal.Desktop` frontend. Ferese's
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native backend implements desktop integration; GTK remains the fallback for
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standard file, print and application dialogs. Install both backends.
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## Native services
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- **Settings:** Ferese's color scheme, accent color, contrast preference and
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reduced-motion setting. Changes are signalled after valid KDL appearance
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changes; malformed saves leave the last valid preferences intact.
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- **Screenshot:** whole-screen and selected-area PNG captures, plus a screen
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color picker. Every capture asks for consent. Interactive requests offer area
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selection. Selection uses `slurp`; captures use Ferese's bounded screenshot IPC.
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The helper must disappear from the compositor before capture starts.
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- **Wallpaper:** a preview and confirmation, then an atomic configuration update.
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Desktop and lock-screen wallpaper can be set independently, or together.
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Ferese copies accepted local images into its own private data directory so
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temporary portal files can disappear safely. Image bytes and decoded dimensions
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are bounded. `theme.background.lock-path` overrides the lock-screen image;
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without it the lock screen follows `theme.background.path`.
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- **Background:** native open-window/app state, change signals and per-instance
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background consent. Legacy autostart requests create managed XDG desktop entries;
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current frontends manage those files themselves. Direct sessions launch standard
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XDG autostart entries after importing the display environment. User overrides,
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Hidden, OnlyShowIn, NotShowIn and TryExec are respected; previews skip autostart.
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- **USB:** native confirmation showing device vendor/model and requested read-only
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or read/write access. The portal frontend handles device enumeration and opening.
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- **ScreenCast:** monitor sharing with a native picker and PipeWire streams.
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See [screen sharing](screen-sharing.md) for lifetime and recording details.
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Native request dialogs use Ferese's theme and are floating windows. Screenshot,
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PickColor, Wallpaper and USB consent dialogs use Wayland parent identifiers to establish
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a transient relationship with the requesting window.
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Cancelling a request or losing the portal frontend terminates its pending helper.
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The packaged `ferese-portals.conf` selects these interfaces explicitly. Existing
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user overrides in `~/.config/xdg-desktop-portal/` may take precedence. Install the
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new compositor, backend and preference files together; screenshot synchronization
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requires the updated compositor IPC.
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## GNOME compatibility audit
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The audit compares the [GNOME backend's registered interfaces](https://github.com/GNOME/xdg-desktop-portal-gnome/blob/main/data/meson.build)
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with the [standard backend D-Bus contracts](https://flatpak.github.io/xdg-desktop-portal/docs/impl-dbus-interfaces.html).
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Matching D-Bus signatures does not establish complete feature parity.
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| Interface | Ferese integration |
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| --- | --- |
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| Settings | Native, including appearance change signals |
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| Screenshot | Native screen/area capture and PickColor; true window capture remains missing |
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| Wallpaper | Native desktop, lock-screen and combined targets |
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| ScreenCast | Native monitors; window sources, persistence and richer metadata remain missing |
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| Access, Account, AppChooser, DynamicLauncher, FileChooser, Notification, Print | Delegated to GTK |
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| Background | Native application state, per-instance consent and XDG autostart |
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| Usb | Native consent; standard frontend handles enumeration and device descriptors |
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| GlobalShortcuts | Missing session-scoped compositor registration and activation signals |
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| RemoteDesktop | Missing authorized input injection and EIS transport |
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| Clipboard | Missing remote-session clipboard transfer |
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| InputCapture | Missing zones, pointer barriers and EIS transport |
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| Lockdown | GTK availability depends on the installed build; no native policy provider |
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| Inhibit | GTK's GNOME-session/ScreenSaver integration does not provide complete Ferese session inhibition |
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The frontend supplies additional APIs such as OpenURI, network monitoring,
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document export and permission storage. Adding a similarly named backend service
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is neither required nor sufficient for those APIs.
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Do not advertise window capture or input services until the compositor provides
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the corresponding operation. Screen crops include occluding windows and cannot
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serve as isolated window captures. GNOME's remote-input features require native
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compositor/session work, rather than substituting successful empty replies.
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## Validation
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Build the backend and run unit tests, then check its contracts on a private bus:
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```sh
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cargo build --locked -p xdg-desktop-portal-ferese
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cargo test --locked -p xdg-desktop-portal-ferese
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python3 scripts/tests/test_portal_contracts.py
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```
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The contract test compares introspection against the installed official backend
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XML, verifies appearance changes and invalid-save retention, and checks that
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sensitive methods reject callers outside the portal frontend. It does not open
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consent dialogs or capture the host desktop. Interactive consent, fractional-scale
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capture, polkit and hotplug still require a live session test.
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