Xila

Appearance

Bootsplash ​

The bootsplash crate provides a focused startup animation layer around the graphics manager and LVGL objects.

Role ​

  • Owns creation and teardown of the boot logo animation sequence.
  • Encapsulates the startup-only animation policy so initialization code does not manipulate LVGL animation internals directly.

Boundaries ​

  • In scope: logo object setup, animation callback wiring, animation lifetime management.
  • Out of scope: window/session management, general UI composition, or reusable animation framework APIs.

Internal structure ​

  • lib.rs: Bootsplash state (lv_anim_t + Logo) and lifecycle methods.
  • error.rs: crate-local error type mapped from graphics failures.
  • One unsafe extern "C" callback (load_animation_callback) updates part opacity across logo children.

Runtime interaction ​

  1. Bootsplash::new acquires graphics::Manager lock.
  2. It uses current screen geometry to compute Logo::get_factor(...) and instantiate logo.
  3. It initializes lv_anim_t (duration, reverse timing, repeat count) and registers callback.
  4. Bootsplash::stop deletes the animation via lv_anim_delete under manager lock.

Dependency model ​

  • Internal runtime dependency: Graphics only.
  • Uses LVGL symbols re-exported through graphics (lv_anim_*, lv_obj_*).

Failure semantics ​

  • Setup failures propagate as crate Error during new.
  • stop can fail through graphics lock/manager-level error propagation.

Extension points ​

  • Animation timing/profile can be changed centrally in Bootsplash::new.
  • Alternate startup visuals can reuse the same lifecycle contract (new/stop) while changing object composition.

Contract vs implementation ​

  • Contract: construct bootsplash with Bootsplash::new(...), stop it with Bootsplash::stop(...).
  • Current implementation: LVGL opacity animation over 4 logo parts using theme primary color and ease-in-out path.

Limitations and trade-offs ​

  • Uses std::os::raw::c_void and LVGL callback ABI, so the implementation is intentionally low-level.
  • Animation is tightly tied to current logo part layout and not exposed as a generic animation graph.

Construction, animation and teardown ​

Bootsplash::new(graphics_manager: &'static graphics::Manager).await obtains the Graphics lock, reads the active LVGL screen size, scales the logo to 30% of the current screen dimension and picks its foreground from the screen's main text color. It constructs a Logo and starts a repeating LVGL opacity animation.

The current animation uses values 64–255, 500 ms forward and 500 ms reverse, an ease-in/out callback and an effectively indefinite repeat count. The callback cycles the four logo parts. Those exact values are design parameters, not part of the general Graphics contract.

Bootsplash::stop(self, graphics_manager).await consumes the splash, takes the Graphics lock, deletes the matching animation callback/variable pair and then lets Rust drop the logo. Call stop explicitly before releasing the logo or ending the graphics runtime: simply dropping an active splash does not execute the animation-deletion path shown in stop.

rust
let splash = bootsplash::Bootsplash::new(graphics_manager).await?;
// Continue initializing the runtime while the graphics loop renders.
splash.stop(graphics_manager).await?;

The example assumes the Graphics service is running and graphics_manager has a 'static lifetime. An initialized screen and progressing LVGL timer handler are prerequisites for visible animation.

Ownership and portability caveats ​

The library owns a boxed lv_anim_t and a Graphics Logo, but the animation is registered through an unsafe C callback and a static mutable animation-part index. It is therefore not a reentrant generic animation component: multiple concurrent splashes and arbitrary LVGL lifecycle resets require care. Its std::os::raw::c_void import means the implementation is not universally no_std even though many Xila libraries are.

References ​