> For the complete documentation index, see [llms.txt](https://viridian-games.gitbook.io/pixel-palette/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://viridian-games.gitbook.io/pixel-palette/core-components/input-system/input-sources-and-priority.md).

# Input Sources & Priority

`TryGetDrawingInput()` checks three devices in strict priority order and returns the first active one:

```
1. Pen (tablet stylus)
   └─ Pen.current.tip.isPressed
   └─ Pen.current.position.ReadValue()      → screen position
   └─ Pen.current.pressure.ReadValue()      → 0..1 pressure (clamped min 0.05)

2. Touch (finger)
   └─ Touchscreen.current.primaryTouch.press.isPressed
   └─ AND !hasSeenMultiTouch  (suppressed during pinch)
   └─ Touchscreen.current.primaryTouch.position.ReadValue()
   └─ pressure = 1.0 (always, touch doesn't report pressure)

3. Mouse (fallback)
   └─ Mouse.current.leftButton.isPressed
   └─ Mouse.current.position.ReadValue()
   └─ pressure = 1.0
```

This means if you have a pen connected, mouse clicks are ignored while the pen is down. Touch takes priority over mouse but not pen.

### Device-Specific Behavior

| Feature        | Pen                     | Touch              | Mouse                   |
| -------------- | ----------------------- | ------------------ | ----------------------- |
| **Drawing**    | Yes, with pressure      | Yes, single finger | Left-click drag         |
| **Pan**        | N/A                     | Two-finger drag    | Right/middle-click drag |
| **Zoom**       | N/A                     | Two-finger pinch   | Scroll wheel            |
| **Pressure**   | Pen pressure (0.05–1.0) | N/A (1.0)          | N/A (1.0)               |
| **Double-tap** | Yes                     | Yes                | Yes                     |

### Touch Pan & Zoom (HandleTouchPanZoom)

Two-finger gesture detection:

```
Count touches with press.isPressed
  if 0 → reset multi-touch flag
  if 1 → single touch (drawing allowed)
  if 2+ → set hasSeenMultiTouch, enter pan/zoom mode
```

Once in two-finger mode:

* **Pan** — average delta of both fingers → `viewController.Pan(delta)`
* **Pinch zoom** — distance change between fingers → `viewController.Zoom(factor, center, camera)`

The `hasSeenMultiTouch` flag prevents single-finger drawing during/after a pinch gesture until all fingers lift.

### Mouse Pan (HandleMousePan)

```
bool panPressed = rightButton || middleButton;
```

Right-click or middle-click hold → tracks `Mouse.current.delta` → `viewController.Pan(delta)`. Sets `isPanning = true` plus a 2-frame `panCooldown` so releasing the button doesn't immediately start drawing at that position.

### Mouse Scroll Zoom (HandleMouseScrollZoom)

```
float scroll = Mouse.current.scroll.ReadValue().y;
```

Scroll up → zoom in (×1.1), scroll down → zoom out (÷1.1). Zoom centers on the mouse cursor position via `viewController.Zoom(factor, screenPos, camera)`.

### Internal State Tracking

* `isDrawing` — true while any stroke is active (pen/touch/mouse down)
* `isPanning` — true while panning via right-click or two-finger touch
* `isSelectionMoving` — true while dragging a selection's content
* `hasSeenMultiTouch` — true after any two-finger touch event, reset on all fingers up
* `quickShapeActive` — true after the hold-still timer triggers quick-shape mode
* `panCooldown` — frame counter preventing accidental drawing after pan release
* `lastTapTime` / `lastTapPosition` — for double-tap detection (0.3s window, 20px distance)

### Camera Resolution

`ResolveEventCamera()` determines which camera to use for screen-to-pixel conversion:

```
canvas.GetCanvas()
  if null → Camera.main
  if ScreenSpaceOverlay → null (screen coords are pixel coords)
  if ScreenSpaceCamera → canvas.worldCamera or Camera.main
```


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