@ue-too/board / index / TouchInputTracker

類別: TouchInputTracker

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:99

Production implementation of TouchContext that tracks multi-touch state.

備註

This class maintains a map of active touch points, storing their initial positions to enable gesture recognition. The state machine uses this context to:

• Calculate pan deltas (difference between initial and current midpoint)
• Calculate zoom factors (change in distance between two touch points)
• Determine gesture type (pan vs zoom based on relative magnitudes)

Touch Point Lifecycle:

1. addTouchPoints: Called on touchstart to register new touches
2. updateTouchPoints: Called on touchmove to update current positions
3. removeTouchPoints: Called on touchend/touchcancel to unregister touches

The initial positions are preserved until the touch ends, allowing continuous calculation of deltas throughout the gesture.

範例

const canvasProxy = new CanvasProxy(canvasElement);
const context = new TouchInputTracker(canvasProxy);
const stateMachine = createTouchInputStateMachine(context);

// When a two-finger touch starts
context.addTouchPoints([
  {ident: 0, x: 100, y: 200},
  {ident: 1, x: 300, y: 200}
]);
console.log(context.getCurrentTouchPointsCount()); // 2

實作

• TouchContext

建構函式

建構函式

new TouchInputTracker(canvas): TouchInputTracker

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:107

參數

canvas

Canvas

回傳

TouchInputTracker

存取器

alignCoordinateSystem

Getter 簽章

get alignCoordinateSystem(): boolean

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:151

Whether to use standard screen coordinate system (vs inverted Y-axis)

回傳

boolean

Setter 簽章

set alignCoordinateSystem(value): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:155

Whether to use standard screen coordinate system (vs inverted Y-axis)

參數

value

boolean

回傳

void

Whether to use standard screen coordinate system (vs inverted Y-axis)

實作了

TouchContext.alignCoordinateSystem

---

canvas

Getter 簽章

get canvas(): Canvas

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:159

Canvas accessor for dimensions and coordinate transformations

回傳

Canvas

Canvas accessor for dimensions and coordinate transformations

實作了

TouchContext.canvas

方法

addTouchPoints()

addTouchPoints(points): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:112

Adds new touch points to tracking

參數

points

TouchPoints[]

回傳

void

實作了

TouchContext.addTouchPoints

---

cleanup()

cleanup(): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:163

回傳

void

實作了

TouchContext.cleanup

---

getCurrentTouchPointsCount()

getCurrentTouchPointsCount(): number

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:126

Returns the current number of active touch points

回傳

number

實作了

TouchContext.getCurrentTouchPointsCount

---

getInitialTouchPointsPositions()

getInitialTouchPointsPositions(idents): TouchPoints[]

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:130

Retrieves the initial positions of specific touch points

參數

idents

number[]

回傳

TouchPoints[]

實作了

TouchContext.getInitialTouchPointsPositions

---

removeTouchPoints()

removeTouchPoints(identifiers): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:118

Removes touch points from tracking by identifier

參數

identifiers

number[]

回傳

void

實作了

TouchContext.removeTouchPoints

---

setup()

setup(): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:165

回傳

void

實作了

TouchContext.setup

---

updateTouchPoints()

updateTouchPoints(pointsMoved): void

定義於: packages/board/src/input-interpretation/input-state-machine/touch-input-context.ts:143

Updates the current positions of touch points

參數

pointsMoved

TouchPoints[]

回傳

void

實作了

TouchContext.updateTouchPoints