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Polypad API Docs

Setup

Our JavaScript API allows you to add interactive Polypad canvases to any website. You simply need to include our JS source file, create a parent element for Polypad, and then call Polypad.create():

<script src="https://static.mathigon.org/api/polypad-en-v4.1.0.js"></script>
<div id="polypad" style="width: 800px; height: 500px;"></div>
<script>Polypad.create(document.querySelector('#polypad'), {apiKey: 'test'})</script>

Polypad requires Custom Web Components and the Web Animations API. If you want to use browsers that don’t support these APIs, you have to include a polyfill, e.g. mathigon.org/polyfill.js.

Our goal is to support the latest version of Chrome, Firefox, Opera and Edge on all mobile and desktop devices.

Note: the polypad-en-v4.x.x.js script needs to be included in the <body>, not the <head> of your HTML document.

JSON Schema

Every Polypad canvas consists of a collection of tiles and strokes. The state of a Polypad can be serialised as JSON, with the following schema:

interface TileData {
  name: string,       // The tile type (since 'type' is a reserved field in many databases)
  x?: number,         // X-position
  y?: number,         // Y-position
  rot?: number,       // Rotation (in degrees)
  color?: string;     // HEX colour (e.g. "#ff0044")
  isFlipped?: boolean;
  status?: 'locked'|'fixed'|'hidden';
  hideHandles?: boolean;
  layer?: 'front'|'normal'|'back'
  labels?: 'fraction'|'percentage'|'decimal'|'hidden';
  cables?: {fromPort?: string, toPort?: string, toTileId: string}[];
  // Many other tile-specific options, as listed at https://mathigon.io/polypad/tiles
}

interface StrokeData {
  points: string;      // SVG path, or geometric expression
  colour?: string;     // HEX colour
  brush: 'pen'|'marker'|'highlighter'
}

interface PolypadOptions {
  toolbar?: string;     // Comma-separated list of toolbar icons to show
  settings?: string;    // Comma-separated list of settings bar icons to show
  sidebar?: string;     // Comma-separated list of sidebar sections to show
  actionbar?: string;   // Comma-separated list of actionbar items to show

  grid?: 'none'|'square2-grid'|'square-dots'|'square-grid'|'tri-dots'|'tri-grid'|'tri2-dots'|'tri2-grid';
  altColors?: boolean;      // Alternate colour scheme for polygons and number bars
  mergeTiles?: boolean;     // Merge number cards or prime factor circles when hovering
  evalEquations?: boolean;  // Evaluate equations
  tileWeights?: string;     // Used for balance scales

  noCopyPaste?: boolean;
  noUndoRedo?: boolean;
  noPinchPan?: boolean;
  noDeleting?: boolean;
  noAudio?: boolean;        // Disable sound effects
  noRotating?: boolean;
  noSnapping?: boolean;
}

interface PolypadData {
  title?: string;
  version?: number;
  options?: PolypadOptions;
  tiles?: Record<string, TileData>;
  strokes?: Record<string, StrokeData>;
}

By default, the maximum length of the tiles and strokes array is 2000. With more items on the same page, you might see performance issues on some devices.

Methods

The Polypad.create() function takes an options argument with many ways to customise Polypad:

interface Polypad {
  create: (options: {
    apiKey?: string;        // Mathigon-issued API key
    userKey?: string;       // Unique identifier for the current user

    sidebar?: boolean;      // Whether to show the sidebar
    toolbar?: boolean;      // Whether to show the toolbar
    settings?: boolean;     // Whether to show the settings bar

    initial?: PolypadData;  // Initial data to show
    isTeacher?: boolean;    // Whether to show editable question fields

    // Whether to show a second, custom sidebar tab
    sidebarTab?: {title: string, icon: string};

    // Override the default theme colours 'red', 'blue', 'green', ...
    themeColours?: Record<string, string>;

    // Provide a way to upload image files: you need to upload the file object to a storage
    // backend and return a promise that resolves with the URL of the uploaded file.
    imageUpload?: (file: File) => Promise<string>;
  }) => PolypadInstance;

  // Get a static image corresponding to a Polypad data object.
  toImage: (data: PolypadData, type?: 'png'|'svg'|'jpg', width?: number, height?: number) => string;

  // Get lists of all available Polypad customisation options.
  getCustomiseOptions: (data) => {sidebar: string[], toolbar: string[], actions: string[], features: string[], settings: string[]};

  // Translates a textbox, equation and image URL instances in a Polypad data object. This function
  // modifies the first argument, and uses the second argument to generate translations.
  translate: (data: PolypadData, translate: (value: string, type: 'html'|'url'|'expr') => string) => string;
}

Polypad.create() then returns a PolypadInstance object with additional methods for manipulating the canvas. Please note that most of these methods don’t type-check their input arguments. If you pass in incorrect data, the behaviour is undefined.

interface PolypadInstance {
  // Bind or unbind event listeners. See below for all supported events.
  on: (event: string, callback: (e: unknown) => void) => void;
  off: (event: string, callback: (e: unknown) => void) => void;

  // Serialize or un-serialize a polypad state from JSON data. See above for types.
  serialize: (maxTiles?: number, maxStrokes?: number, maxStrokeLength?: number) => PolypadData;
  unSerialize: (data: PolypadData) => void;

  // Create an image of a given size. This asynchronous function returns a Data URI string.
  image: (width: number, height: number, type?: 'png'|'jpg'|'svg') => Promise<string>;

  // Add, update or delete a tile or stroke. .add() returns the ID of the new item. Note that
  // you cannot update strokes, or update the 'name' property of a tile once created.
  add: (data: TileData|StrokeData) => string;
  update: (id: string, properties: Partial<TileData>) => void;
  delete: (...ids: string[]) => void;

  // Paste new tile data. Unlilke the "add" function, this de-dupes any tile IDs, dynamic geometry
  // keys and connection cables, so that the same data can be pasted multiple times.
  paste: (data: Record<string, TileData>) => void;

  // Get the current user selection, or programmatically select multiple existing tiles.
  getSelection: () => string[];
  select: (...tileIds: string[]) => void;

  // Undo or redo the latest changes to the canvas.
  undo: () => void;
  redo: () => void;

  // Set the background grid or display options. See the `options` event for more details.
  setOptions: (e: Partial<PolypadOptions>) => void;

  // Clear all tiles on the current canvas. Unline .unSerialize({}), this action can be undone.
  clear: () => void;

  // Get or update the visible viewport of the canvas, or reset it to its initia position.
  getViewport: () => {x: number; y: number; zoom: number};
  setViewport: (x: number, y: number, zoom: number) => void;
  resetViewport: () => void;

  // Call this function to manually trigger a resize of the Polypad container. We are already
  // using window.resize() and the ResizeObserver API (if available in the Browser).
  resize: () => void;
  
  // Show a floating hand gesture that animates either clicking on a DOM element (no slide)
  // or dragging a DOM element by a certain distance (with slide). The gesture disappears as
  // soon as the target is interacted with.
  showGesture: (selector: string, slide?: {x: number, y: number}) => void;

  // Enable keyboard and accessibility shortcuts. See below for details
  bindKeyboardEvents: (keys?: KeyboardShortcuts) => void;
  
  // Remove and clean up this Polypad instance. This action is irreversible, and any further
  // interaction with the instance class may throw undefined Errors.
  destroy(): void;

  // Expand, collapase or toggle the sidebar on the left. With no arguments, the current state
  // is flipped, or you can explicitly specify and expanded or collapsed state.
  toggleSidebar: (expanded?: boolean) => void;

  // Add a custom button to the toolbar or sidebar. You can provide either an HTML string or a
  // DOM Element, and the method returns the new <button> DOM element.
  addCustomButton: (target: 'toolbar'|'settings', body: string|Element = '') => Element
}

Keyboard Events

Using the .bindKeyboardEvents() method, you can enable a large number of built-in keyboard shortcuts. You can always also use the META/CMD key instead of CTRL. Events are bound just to the Polypad instance, and won’t be triggered unless Polypad is focussed. Events always include:

  • Press SPACE or ENTER to “click” the currently focussed button (for accessibility).
  • CTRL+Z to undo (or redo if SHIFT is also pressed) and CTRL+Y to redo.
  • BACKSPACE, CLEAR or DELETE to delete all currently selected tiles.
  • C to create a copy of all currently selected tiles.
  • CTRL+A to select all tiles.
  • Default browser CUT, COPY and PASTE events (e.g. using CTRL+C).
  • Hold SPACE to temporarily switch to the pan tool.
  • R to rotate the current selection (reverse rotation of SHIFT is also pressed).
  • ARROW keys to move the currently selected tiles up, down left or right.

In addition, you can pass a parameter to enable some additional shortcuts when specific letter keys are pressed. To prevent this, pass {} as an argument. If you do not pass an arguments, these defaults will be used:

type ToolShortcut = ['tool', 'move'|'pen'|'eraser'|'text'|'pan'|'geo'|'equation'];
type FocusShortcut = ['focus', 'sidebar'|'toolbar'|'canvas'|'actionbar'];
type KeyboardShortcuts = Record<string, ToolShortcut|FocusShortcut>;

const KEYBOARD_SHORTCUTS: KeyboardShortcuts = {
  v: ['tool', 'move'],
  p: ['tool', 'pen'],
  g: ['tool', 'geo'],
  t: ['tool', 'text'],
  q: ['tool', 'equation'],
  e: ['tool', 'eraser'],
  s: ['focus', 'sidebar'],
  d: ['focus', 'toolbar'],
  f: ['focus', 'canvas'],
  a: ['focus', 'actionbar']
};

UI Customisation

The PolypadData.options object contains properties to customise which UI elements are visible, using comma-separated strings. If this field is empty, all items will be shown. Otherwise, only the selected items will be shown.

Toolbar

Options include move, pen, geo, text, equation, eraser, image, and color.

Settings Bar

Options include fullscreen, grid, customise and download. The undo/redo buttons can be hidden using the .noUndoRedo Polypad option, and the pan/zoom buttons can be hidden using the .noPinchPan option.

Options include geometry, polygons, polyominoes, tangram, penrose, pentagons, solids, measuring, patterns, numbers, number-tiles, number-bars, number-frames, number-cards, number-line, primes, number-dots, number-grid, number-tools, fractions, fraction-bars, fraction-circles, algebra, algebra, balance, axes, sliders, probability, probability, charts, playing-cards, polyhedral-dice, non-trans-dice, applications, logic, chess, clocks and dominoes.

Actionbar

Many options, that are simply the label/tooltip of each item, in lowercase and kebab-case. Examples include copy, delete or split-tiles.

Custom Sidebar Tab

Using the sidebarTab property, you can enable a second, custom tab for the sidebar, similar to Mathigon’s version of Polypad. You need to specify a title, as well as an icon ID.

The content of the sidebar can be simply added into the <div></div> that the Polypad instance is attached to. It will be automatically shown in the correct place using the <slot></slot> element. See example.html for an example!

Events

Using the .on() and .off() methods on PolypadInstance, you can bind and unbind many different event listeners. The following events are supported:

.on('change')

This event is triggered whenever the state of the Polypad changes because the user has added, updated or deleted a stroke or tile. Note that multiple different tiles can change at once, but the event is only triggered once at the end of a move or rotate action.

Callback Options: Record<string, [TileData|StrokeData|undefined, TileData|StrokeData|undefined]>

The callback options is a map of every added, deleted or modified tile or stroke, keyed by their IDs. Every value is an array of the [pevious, updated] state of the corresponding tile or stroke. For example, added items are of the form [undefined, TileData|StrokeData], deleted items are of the form [TileData|StrokeData, undefined], and modified tiles are of the form [Partial<TileData>, Partial<TileData>] containing just the changed properties. This is useful for maintaining your own undo/redo stacks. Note that strokes cannot be modified – only created or deleted.

.on('viewport')

Triggered whenever the position of the visible viewport changes, for example because the user pans or zooms. Note that the viewport is not part of the “state” of a polypad. When calling .unSerialize() or .resetViewport(), we update the viewport so that all tiles and strokes are visible and centered.

Callback Options: {x: number, y: number, zoom: number}

.on('undo'), .on('redo')

Triggered on undo and redo: both from a user input (e.g. clicking the undo button or CTRL + Z on the keyboard), or programatically (e.g. calling .undo() above), You can call .preventDefault() on the event object to prevent the built-in undo/redo handling, and instead apply changes from a custom stack of changes.

Callback Options: Event

.on('options')

Triggered whenever the user changes the canvas options using the settings bar on the left. The available options are listed in the PolypadOptions object.

Callback Options: Partial<PolypadOptions>

.on('selection')

Triggered whenever the current selection changes.

Callback Options: {tiles: string[]}

.on('move')

This event is triggered continuously while users are moving one or more tiles. The Callback argument contains the ID and the current position of all currently selected tiles.

Callback Options: {tiles: {id: string, x: number, y: number}[]}

Internationalisation

The Polypad API is currently available in two different languages, each ith separate JS bundles:

  • polypad-en-v4.x.x.js – English
  • polypad-es-v4.x.x.js – Spanish

Additional languages will be added in the future.


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