Tactility/Documentation/screensavers.md
Shadowtrance c05d46a28c
Screensavers (#462)
Adds screensavers in addition to the backlight idle off. 
More info in screensavers.md

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

* **New Features**
  * Added a screensaver system with multiple styles (Bouncing Balls, Mystify, Matrix Rain) and a common screensaver interface; auto-starts after inactivity, dismisses on interaction, and supports auto-off/backlight behavior.
  * New Display setting and UI dropdown to choose and persist the screensaver.

* **Documentation**
  * Added comprehensive screensaver docs covering usage, extension, and configuration.

* **Chores**
  * Registered the display-idle service.

* **Bug Fixes**
  * Updated LVGL API calls to match renamed functions.

<sub>✏️ Tip: You can customize this high-level summary in your review settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
2026-01-27 17:21:16 +01:00

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# DisplayIdle Service
The DisplayIdle service manages screen timeout, screensavers, and backlight control for Tactility devices.
## Features
### Screen Timeout
When enabled, the display will automatically dim after a configurable period of inactivity. Timeout options:
- 15 seconds
- 30 seconds
- 1 minute
- 2 minutes
- 5 minutes
- Never
### Screensavers
Four screensaver options are available:
| Type | Description |
|------|-------------|
| **None** | Black screen only, backlight turns off immediately |
| **Bouncing Balls** | Colored balls bouncing around the screen |
| **Mystify** | Classic Windows-style polygon trails with color-changing effects |
| **Matrix Rain** | Digital rain effect with terminal-style grid movement, 6-color gradient trails, glow effects, and random character flicker |
### Auto-Off Feature
After 5 minutes of screensaver activity, the screensaver animation stops and the backlight turns off completely to save power. Touching the screen restores normal operation.
## Public API
The service exposes a public header for external control:
```cpp
#include <Tactility/service/displayidle/DisplayIdleService.h>
// Get service instance
auto displayIdle = tt::service::displayidle::findService();
// Force start screensaver immediately
displayIdle->startScreensaver();
// Force stop screensaver and restore backlight
displayIdle->stopScreensaver();
// Check if screensaver is currently active
bool active = displayIdle->isScreensaverActive();
// Reload settings (call after external settings changes)
displayIdle->reloadSettings();
```
## Architecture
### Files
| File | Purpose |
|------|---------|
| `DisplayIdleService.h` | Public header with service interface |
| `DisplayIdle.cpp` | Service implementation |
| `Screensaver.h` | Base class for screensaver implementations |
| `BouncingBallsScreensaver.h/cpp` | Bouncing balls screensaver |
| `MystifyScreensaver.h/cpp` | Mystify polygon screensaver |
| `MatrixRainScreensaver.h/cpp` | Matrix digital rain screensaver |
### Screensaver Base Class
All screensavers inherit from the `Screensaver` base class:
```cpp
class Screensaver {
public:
virtual void start(lv_obj_t* overlay, lv_coord_t screenW, lv_coord_t screenH) = 0;
virtual void stop() = 0;
virtual void update(lv_coord_t screenW, lv_coord_t screenH) = 0;
};
```
### Adding a New Screensaver
1. Create header and implementation files inheriting from `Screensaver`
2. Add enum value to `ScreensaverType` in `DisplaySettings.h` (before `Count` sentinel)
3. Add string conversion in `DisplaySettings.cpp` (`toString` and `fromString`)
4. Add dropdown option in `Display.cpp` (order must match enum order)
5. Add case in `DisplayIdle.cpp` `activateScreensaver()` switch
6. Include the new header in `DisplayIdle.cpp`
**Note:** The `ScreensaverType::Count` sentinel must always be the last enum value - it's used for bounds checking in the UI.
## Settings Integration
Settings are stored in `/data/settings/display.properties` and managed through `DisplaySettings.h`:
```cpp
struct DisplaySettings {
Orientation orientation;
uint8_t gammaCurve;
uint8_t backlightDuty;
bool backlightTimeoutEnabled;
uint32_t backlightTimeoutMs;
ScreensaverType screensaverType;
};
```
The Display app (`Display.cpp`) provides the UI for configuring these settings and notifies the DisplayIdle service when settings change via `reloadSettings()`.
## Timing
- Service tick interval: 50ms
- Wake activity threshold: 100ms
- Screensaver auto-off: 5 minutes (6000 ticks)