QPlayer

An extensible cross-platform music player with a QML-rendered UI Powered by qml4j

The UI uses no native Views. Every control is described in QML and rendered by qml4j, except the lyric-page body (per-syllable scrolling, fluid backdrop), which the host draws directly through Skija. qml4j is itself a QML runtime written in pure Java.

Android and desktop load the same QML and the same player-core logic: one UI running in two host shells.

🎶 Structure QPlayer is a player shell plus a plugin system.

QPlayer itself contains no online music source and distributes no source code for one. Installing a JavaScript source plugin adds recommendations, aggregate search, playlists, login, likes, recent plays and heart mode; pages appear according to the capabilities a plugin declares, and match the native pages. Without a plugin, it is a local player.

That boundary shapes the rest of the design. Plugins run in an isolated Rhino realm; only permissions declared in the manifest and confirmed by the user take effect; every field a plugin returns is validated before it reaches the UI; and a plugin contributes no QML, only a description of a dialog's contents, which QPlayer renders with its own components.

🎶Features ・Playback　A local library, a shared queue, and three play modes (list loop, shuffle, repeat one). Online entities use collision-free provider:kind:id identifiers. A foreground MediaSession service drives the lockscreen, notification and bluetooth transport, with auto-advance, position sync, pause-on-call and ducking on transient focus loss.

・Lyric page　Drawn by the host directly through Skija rather than QML: per-syllable scrolling, a fluid backdrop tinted from the cover, romanization and translation, and a Material wavy progress bar. Lyrics come from the active source plugin or from local files. On Android they are also published natively to Lyricon for the status bar.

・Interface　The whole UI is QML (md3.Core) running on the qml4j engine. The theme can be reseeded from the current cover (Monet dynamic color, optional), with dark, light and follow-system modes, in Simplified Chinese or English. Layout is width-driven (MD3 breakpoints 600 / 840): a bottom bar when narrow, a left NavigationRail when wide, and a playlist grid whose column count follows the width, so Android landscape and tablets require no separate work.

・Desktop　The same QML and player-core on LWJGL3 + GLFW, rendered with Skija. The OpenGL and Vulkan backends are switchable at startup. A taskbar icon and a system tray whose menu mirrors the transport are provided, and minimizing to the tray destroys the render thread and GPU resources and rebuilds them on restore, while playback and UI state are preserved.

・Plugin safety　Signed .qplug packages, built-in source repositories pinned to a publisher key, a permission sheet at install time, one isolated Rhino realm per plugin, network-domain grants and a namespaced credential vault. Plugin dialogs are declared by the plugin and rendered by QPlayer, so they follow the app's theme and cannot imitate host chrome they were not given.

🎶Credential storage and the security boundary ・QPlayer encrypts each plugin's login credentials with authenticated AES-GCM in a plugin-specific namespace, and protects the random data key with Android Keystore, macOS Keychain, Windows DPAPI or Linux Secret Service/KWallet whenever one is available. If the system store is unavailable, the user may explicitly fall back to a local key readable only by the current user.

・This feature provides data-at-rest protection, not protection against malware already running locally. It reduces the risk of restoring a login from copied credential files, configuration directories, backups or old drives, and prevents other unprivileged operating-system accounts from reading the credentials directly.

▶ Interface languages: Chinese, English

📄 License Apache License 2.0.