@ue-too/board / index / Board

類別: Board

定義於: packages/board/src/boardify/index.ts:199

Main user-facing API class that provides an infinite canvas with pan, zoom, and rotate capabilities.

The Board class is the primary entry point for using the board package. It integrates all subsystems including camera management, input handling, and state machines into a simple, unified API for creating interactive 2D canvases with advanced camera controls.

備註

Architecture Overview

The Board class orchestrates several subsystems:

• Camera System: Manages viewport transformations (pan/zoom/rotate) through ObservableBoardCamera. The camera can be configured with boundaries, zoom limits, and various movement constraints.

• Input System: Processes user input through state machines for both mouse/keyboard/trackpad (KMT) and touch events. Input is parsed, interpreted, and translated into camera movements.

• Camera Rig: Enforces constraints and restrictions on camera movement (boundaries, zoom limits, clamping behavior). See CameraRig for details.

• Camera Multiplexer: Coordinates between different camera control sources (user input, animations, programmatic control) to ensure smooth transitions. See CameraMux for details.

Coordinate Systems

The Board supports three coordinate systems:

1. World Coordinates: The infinite canvas space where your content lives. When the camera is at position (0, 0) with no zoom or rotation, world coordinates map directly to viewport coordinates.

2. Viewport Coordinates: The visible area of the canvas relative to the camera center. The camera center is at (0, 0) in viewport space, with coordinates extending in both directions based on the canvas size.

3. Window/Canvas Coordinates: The browser's coordinate system, with (0, 0) at the top-left corner of the canvas element. Use convertWindowPoint2WorldCoord to convert from window to world space.

By default, alignCoordinateSystem is true, which means the Y-axis points down (standard HTML canvas orientation). Set it to false to use a mathematical coordinate system where Y points up.

Main Features

• Camera Control: Pan, zoom, and rotate the viewport through user input or programmatic API
• Boundaries: Define world-space boundaries to constrain camera movement
• Zoom Limits: Set minimum and maximum zoom levels
• Input Modes: Support for mouse/keyboard/trackpad and touch input with customizable parsers
• Event System: Subscribe to camera events (pan, zoom, rotate) and input events
• Coordinate Conversion: Convert between window and world coordinates
• Flexible Configuration: Extensive options for restricting/clamping camera movement

Examples

Basic setup with drawing

const canvasElement = document.querySelector("canvas") as HTMLCanvasElement;
const board = new Board(canvasElement);

function draw(timestamp: number) {
  board.step(timestamp);

  // Because board can be initialized without a canvas element,
  // the context can be undefined until the canvas is attached
  if(board.context == undefined) {
    return;
  }

  // Draw after the board has stepped
  // The coordinate system has (0, 0) at the center of the canvas when camera position is at (0, 0)
  board.context.beginPath();
  board.context.rect(0, 0, 100, 100);
  board.context.fill();

  requestAnimationFrame(draw);
}

requestAnimationFrame(draw);

Handling camera and input events

const board = new Board(canvasElement);

// Listen to camera pan events
board.on('pan', (event, cameraState) => {
  console.log('Camera panned to:', cameraState.position);
});

// Listen to camera zoom events
board.on('zoom', (event, cameraState) => {
  console.log('Camera zoom level:', cameraState.zoomLevel);
});

// Listen to raw input events (before camera movement)
board.onInput('pan', (event) => {
  console.log('User is panning');
});

Configuring boundaries and zoom limits

const board = new Board(canvasElement);

// Set world boundaries
board.camera.boundaries = {
  min: { x: -1000, y: -1000 },
  max: { x: 1000, y: 1000 }
};

// Set zoom limits
board.camera.setMinZoomLevel(0.1);
board.camera.setMaxZoomLevel(5.0);

// Ensure entire viewport stays within boundaries
board.limitEntireViewPort = true;

// Clamp camera position to boundaries
board.clampTranslation = true;
board.clampZoom = true;

Converting window coordinates to world coordinates

const board = new Board(canvasElement);

canvasElement.addEventListener('click', (event) => {
  const windowPoint = { x: event.clientX, y: event.clientY };
  const worldPoint = board.convertWindowPoint2WorldCoord(windowPoint);
  console.log('Clicked at world position:', worldPoint);
});

Initialize board without canvas, attach canvas later

const board = new Board();

// Attach canvas later
const canvasElement = document.createElement('canvas');
document.body.appendChild(canvasElement);
board.attach(canvasElement);

參閱

• ObservableBoardCamera for camera API details
• CameraRig for camera constraint configuration
• CameraMux for camera control coordination

存取器

alignCoordinateSystem

Getter 簽章

get alignCoordinateSystem(): boolean

定義於: packages/board/src/boardify/index.ts:525

回傳

boolean

Setter 簽章

set alignCoordinateSystem(align): void

定義於: packages/board/src/boardify/index.ts:519

Description

This is an attribute that determines if the coordinate system should be aligned with the one of the HTML canvas element. The default is true. If you set this to true, the coordinate system will be aligned with the one of the HTML canvas element. If you change this value during runtime, you should update the context to be aligned with the new coordinate system. (just call board.context again)

參數

align

boolean

回傳

void

---

camera

Getter 簽章

get camera(): ObservableBoardCamera

定義於: packages/board/src/boardify/index.ts:614

Description

The underlying camera of the board. The camera of the board can be switched. The boundaries are based on camera meaning you can have cameras with different boundaries, and you can switch between them during runtime.

回傳

ObservableBoardCamera

Setter 簽章

set camera(camera): void

定義於: packages/board/src/boardify/index.ts:618

參數

camera

ObservableBoardCamera

回傳

void

---

cameraMux

Getter 簽章

get cameraMux(): CameraMux

定義於: packages/board/src/boardify/index.ts:628

回傳

CameraMux

Setter 簽章

set cameraMux(cameraMux): void

定義於: packages/board/src/boardify/index.ts:632

參數

cameraMux

CameraMux

回傳

void

---

canvasDimensions

Getter 簽章

get canvasDimensions(): CanvasDimensions

定義於: packages/board/src/boardify/index.ts:941

回傳

CanvasDimensions

---

clampRotation

Getter 簽章

get clampRotation(): boolean

定義於: packages/board/src/boardify/index.ts:921

回傳

boolean

Setter 簽章

set clampRotation(value): void

定義於: packages/board/src/boardify/index.ts:925

參數

value

boolean

回傳

void

---

clampTranslation

Getter 簽章

get clampTranslation(): boolean

定義於: packages/board/src/boardify/index.ts:905

回傳

boolean

Setter 簽章

set clampTranslation(value): void

定義於: packages/board/src/boardify/index.ts:909

參數

value

boolean

回傳

void

---

clampZoom

Getter 簽章

get clampZoom(): boolean

定義於: packages/board/src/boardify/index.ts:913

回傳

boolean

Setter 簽章

set clampZoom(value): void

定義於: packages/board/src/boardify/index.ts:917

參數

value

boolean

回傳

void

---

context

Getter 簽章

get context(): CanvasRenderingContext2D | undefined

定義於: packages/board/src/boardify/index.ts:549

Description

The context used to draw on the canvas. If alignCoordinateSystem is false, this returns a proxy that automatically negates y-coordinates for relevant drawing methods.

回傳

CanvasRenderingContext2D | undefined

---

fullScreen

Getter 簽章

get fullScreen(): boolean

定義於: packages/board/src/boardify/index.ts:533

Description

Determines if the board should be full screen. If this is set to true, the width and height of the board will be set to the window's inner width and inner height respectively, and the width and height of the board will resize with the window.

回傳

boolean

Setter 簽章

set fullScreen(value): void

定義於: packages/board/src/boardify/index.ts:537

參數

value

boolean

回傳

void

---

height

Getter 簽章

get height(): number

定義於: packages/board/src/boardify/index.ts:510

回傳

number

---

inputOrchestrator

Getter 簽章

get inputOrchestrator(): InputOrchestrator

定義於: packages/board/src/boardify/index.ts:485

回傳

InputOrchestrator

---

kmtParser

Getter 簽章

get kmtParser(): KMTEventParser

定義於: packages/board/src/boardify/index.ts:588

回傳

KMTEventParser

Setter 簽章

set kmtParser(parser): void

定義於: packages/board/src/boardify/index.ts:578

Description

The strategy used to handle the keyboard, mouse events. The default strategy is the DefaultBoardKMTStrategy. You can implement your own strategy by implementing the BoardKMTStrategy interface.

參數

parser

KMTEventParser

回傳

void

---

limitEntireViewPort

Getter 簽章

get limitEntireViewPort(): boolean

定義於: packages/board/src/boardify/index.ts:570

回傳

boolean

Setter 簽章

set limitEntireViewPort(value): void

定義於: packages/board/src/boardify/index.ts:560

Description

Determines the behavior of the camera when the camera is at the edge of the boundaries. If set to true, the entire view port would not move beyond the boundaries. If set to false, only the center of the camera is bounded by the boundaries.

參數

value

boolean

回傳

void

---

maxHalfTransHeight

Getter 簽章

get maxHalfTransHeight(): number | undefined

定義於: packages/board/src/boardify/index.ts:756

Description

The max translation height of the camera. This is the maximum distance the camera can move in the vertical direction.

回傳

number | undefined

---

maxHalfTransWidth

Getter 簽章

get maxHalfTransWidth(): number | undefined

定義於: packages/board/src/boardify/index.ts:763

Description

The max translation width of the camera. This is the maximum distance the camera can move in the horizontal direction.

回傳

number | undefined

---

restrictRelativeXTranslation

Getter 簽章

get restrictRelativeXTranslation(): boolean

定義於: packages/board/src/boardify/index.ts:857

回傳

boolean

Setter 簽章

set restrictRelativeXTranslation(value): void

定義於: packages/board/src/boardify/index.ts:873

參數

value

boolean

回傳

void

---

restrictRelativeYTranslation

Getter 簽章

get restrictRelativeYTranslation(): boolean

定義於: packages/board/src/boardify/index.ts:861

回傳

boolean

Setter 簽章

set restrictRelativeYTranslation(value): void

定義於: packages/board/src/boardify/index.ts:877

參數

value

boolean

回傳

void

---

restrictRotation

Getter 簽章

get restrictRotation(): boolean

定義於: packages/board/src/boardify/index.ts:897

回傳

boolean

Setter 簽章

set restrictRotation(value): void

定義於: packages/board/src/boardify/index.ts:901

參數

value

boolean

回傳

void

---

restrictXTranslation

Getter 簽章

get restrictXTranslation(): boolean

定義於: packages/board/src/boardify/index.ts:865

回傳

boolean

Setter 簽章

set restrictXTranslation(value): void

定義於: packages/board/src/boardify/index.ts:881

參數

value

boolean

回傳

void

---

restrictYTranslation

Getter 簽章

get restrictYTranslation(): boolean

定義於: packages/board/src/boardify/index.ts:869

回傳

boolean

Setter 簽章

set restrictYTranslation(value): void

定義於: packages/board/src/boardify/index.ts:885

參數

value

boolean

回傳

void

---

restrictZoom

Getter 簽章

get restrictZoom(): boolean

定義於: packages/board/src/boardify/index.ts:889

回傳

boolean

Setter 簽章

set restrictZoom(value): void

定義於: packages/board/src/boardify/index.ts:893

參數

value

boolean

回傳

void

---

touchParser

Getter 簽章

get touchParser(): TouchEventParser

定義於: packages/board/src/boardify/index.ts:606

回傳

TouchEventParser

Setter 簽章

set touchParser(parser): void

定義於: packages/board/src/boardify/index.ts:596

Description

The parser used to handle touch events. The default parser is the DefaultTouchParser. You can have your own parser by implementing the BoardTouchParser interface.

參數

parser

TouchEventParser

回傳

void

---

width

Getter 簽章

get width(): number

定義於: packages/board/src/boardify/index.ts:506

回傳

number

方法

convertWindowPoint2WorldCoord()

convertWindowPoint2WorldCoord(clickPointInWindow): Point

定義於: packages/board/src/boardify/index.ts:708

TODO add the option to make the camera position to be at the top left corner of the canvas; or better yet any point in the viewport (within the viewport boundaries)

參數

clickPointInWindow

Point

The point in window coordinates to convert.

回傳

Point

The converted point in world coordinates.

Description

Converts a point from window coordinates to world coordinates.

---

disableEventListeners()

disableEventListeners(): void

定義於: packages/board/src/boardify/index.ts:475

回傳

void

---

enableEventListeners()

enableEventListeners(): void

定義於: packages/board/src/boardify/index.ts:480

回傳

void

---

getCameraRig()

getCameraRig(): CameraRig

定義於: packages/board/src/boardify/index.ts:929

回傳

CameraRig

---

on()

on<K>(eventName, callback): UnSubscribe

定義於: packages/board/src/boardify/index.ts:731

型別參數

K

K extends keyof CameraEventMap

參數

eventName

K

The event name to listen for. The events are "pan", "zoom", and "rotate".

callback

(event, cameraState) => void

The callback function to call when the event is triggered. The event provided to the callback is different for the different events.

回傳

UnSubscribe

The converted point in world coordinates.

Description

Add an camera movement event listener. The events are "pan", "zoom", and "rotate". There's also an "all" event that will be triggered when any of the above events are triggered.

---

onCanvasDimensionChange()

onCanvasDimensionChange(callback): () => void

定義於: packages/board/src/boardify/index.ts:937

參數

callback

(dimensions) => void

回傳

(): void

回傳

void

---

onInput()

onInput<K>(eventName, callback): UnsubscribeToUserRawInput

定義於: packages/board/src/boardify/index.ts:746

型別參數

K

K extends keyof RawUserInputEventMap

參數

eventName

K

callback

(event) => void

回傳

UnsubscribeToUserRawInput

Description

Add an input event listener. The events are "pan", "zoom", and "rotate". This is different from the camera event listener as this is for input events. There's also an "all" event that will be triggered when any of the above events are triggered. Input event does not necesarily mean that the camera will move. The input events are the events triggered when the user interacts with the board.

---

setInputMode()

setInputMode(mode): void

定義於: packages/board/src/boardify/index.ts:933

參數

mode

"kmt" | "trackpad"

回傳

void

---

step()

step(timestamp): void

定義於: packages/board/src/boardify/index.ts:645

參數

timestamp

number

回傳

void

Description

This is the step function that is called in the animation frame. This function is responsible for updating the canvas context and the camera state.

Helper Methods

setMaxTransWidthWithFixedMaxBoundary()

setMaxTransWidthWithFixedMaxBoundary(value): void

定義於: packages/board/src/boardify/index.ts:826

參數

value

number

回傳

void

Description

This function sets the max translation width of the camera while fixing the minimum x boundary.

---

setMaxTransWidthWithFixedMinBoundary()

setMaxTransWidthWithFixedMinBoundary(value): void

定義於: packages/board/src/boardify/index.ts:791

參數

value

number

回傳

void

Description

This function sets the max translation width of the camera while fixing the minimum x boundary.

LifeCycle

建構函式

new Board(canvas?, debug?): Board

定義於: packages/board/src/boardify/index.ts:303

Creates a new Board instance with an optional canvas element.

The constructor initializes all subsystems including the camera, input parsers, state machines, and event publishers. The board can be created with or without a canvas element - if no canvas is provided, you can attach one later using attach.

參數

canvas?

HTMLCanvasElement

Optional HTMLCanvasElement to attach to the board. If provided, the board will immediately initialize with this canvas. If omitted, you must call attach before the board can be used.

debug?

boolean = false

Optional debug flag that enables willReadFrequently hint on the canvas context, which optimizes the canvas for frequent readback operations. Default is false. Only use this if you need to frequently read pixel data from the canvas.

回傳

Board

備註

Initialization Sequence

When the constructor is called, it performs the following initialization:

1. Camera Setup: Creates a DefaultBoardCamera with default boundaries of ±50,000 units in both X and Y directions. This provides a large working area for most use cases.

2. Canvas Proxy: Initializes a CanvasProxy that observes canvas dimension changes and automatically updates the camera's viewport dimensions.

3. Camera Rig: Creates a CameraRig with default configuration:

   • limitEntireViewPort: true - Entire viewport is constrained within boundaries
   • clampTranslation: true - Camera position is clamped to boundaries
   • clampZoom: true - Zoom level is clamped to min/max limits
   • All translation restrictions are disabled by default

4. Input System: Initializes both keyboard/mouse/trackpad (KMT) and touch input parsers, state machines, and the input orchestrator that coordinates camera control.

5. Canvas Attachment (if canvas provided): If a canvas element is provided, it's immediately attached and the viewport dimensions are synchronized with the canvas size.

Default Configuration

The board is created with sensible defaults:

• World boundaries: (-50000, -50000) to (50000, 50000)
• Coordinate system: Aligned with HTML canvas (Y-axis points down)
• Camera position: (0, 0)
• Zoom level: 1.0
• Rotation: 0 radians
• Full screen: disabled

You can customize these defaults after construction by setting properties on the board or camera.

Examples

Create board with canvas element

const canvas = document.querySelector('canvas') as HTMLCanvasElement;
const board = new Board(canvas);
// Board is ready to use immediately

Create board without canvas, attach later

const board = new Board();
// ... later, when canvas is ready
const canvas = document.createElement('canvas');
document.body.appendChild(canvas);
board.attach(canvas);

Enable debug mode for pixel readback

const board = new Board(canvas, true);
// Now getImageData() and similar operations will be optimized

參閱

• attach for attaching a canvas after construction
• tearDown for cleanup when done with the board

---

attach()

attach(canvas, debug): void

定義於: packages/board/src/boardify/index.ts:454

Attaches a canvas element to the board, enabling rendering and input handling.

This method connects a canvas element to the board's rendering and input systems. It must be called before the board can be used if no canvas was provided to the constructor. If a canvas was already attached, this method will replace it with the new canvas.

參數

canvas

HTMLCanvasElement

The HTMLCanvasElement to attach to the board. This canvas will be used for rendering and will receive all input events.

debug

boolean = false

Optional debug flag that enables willReadFrequently hint on the canvas context. Default is false. Set to true if you need to frequently read pixel data from the canvas, which will optimize the context for readback operations.

回傳

void

備註

When a canvas is attached, the following happens:

1. Context Creation: A 2D rendering context is obtained from the canvas with the specified debug settings.

2. Input Parser Attachment: Both KMT (keyboard/mouse/trackpad) and touch input parsers are attached to the canvas to begin receiving input events.

3. Canvas Proxy Attachment: The canvas proxy begins observing the canvas for dimension changes, automatically updating the camera's viewport dimensions when the canvas is resized.

4. Zoom Level Synchronization: If limitEntireViewPort is enabled, the minimum zoom level is calculated and set to ensure the entire viewport can fit within the camera boundaries.

5. Coordinate System Setup: Both standard and Y-reversed rendering contexts are created to support both coordinate system modes (see alignCoordinateSystem).

Examples

Attach canvas during construction

const canvas = document.querySelector('canvas') as HTMLCanvasElement;
const board = new Board(canvas);
// No need to call attach() - already attached

Attach canvas after construction

const board = new Board();

// Later, when canvas is ready...
const canvas = document.createElement('canvas');
canvas.width = 800;
canvas.height = 600;
document.body.appendChild(canvas);

board.attach(canvas);
// Board is now ready to use

Switch to a different canvas

const board = new Board(canvas1);

// Later, switch to a different canvas
const canvas2 = document.querySelector('#other-canvas') as HTMLCanvasElement;
board.attach(canvas2);
// Board is now rendering to canvas2

參閱

• tearDown for detaching and cleaning up
• context for accessing the rendering context

---

tearDown()

tearDown(): void

定義於: packages/board/src/boardify/index.ts:493

回傳

void

Description

This function is used to clean up the board. It removes all the event listeners and disconnects the resize observer and the attribute observer.