Method constructor

src/core/core.controller.js:123–195

(item, userConfig)

  // eslint-disable-next-line max-statements
  constructor(item, userConfig) {
    const config = this.config = new Config(userConfig);
    const initialCanvas = getCanvas(item);
    const existingChart = getChart(initialCanvas);
    if (existingChart) {
      throw new Error(
        'Canvas is already in use. Chart with ID \'' + existingChart.id + '\'' +
				' must be destroyed before the canvas with ID \'' + existingChart.canvas.id + '\' can be reused.'
      );
    }

    const options = config.createResolver(config.chartOptionScopes(), this.getContext());

    this.platform = new (config.platform || _detectPlatform(initialCanvas))();
    this.platform.updateConfig(config);

    const context = this.platform.acquireContext(initialCanvas, options.aspectRatio);
    const canvas = context && context.canvas;
    const height = canvas && canvas.height;
    const width = canvas && canvas.width;

    this.id = uid();
    this.ctx = context;
    this.canvas = canvas;
    this.width = width;
    this.height = height;
    this._options = options;
    // Store the previously used aspect ratio to determine if a resize
    // is needed during updates. Do this after _options is set since
    // aspectRatio uses a getter
    this._aspectRatio = this.aspectRatio;
    this._layers = [];
    this._metasets = [];
    this._stacks = undefined;
    this.boxes = [];
    this.currentDevicePixelRatio = undefined;
    this.chartArea = undefined;
    this._active = [];
    this._lastEvent = undefined;
    this._listeners = {};
    /** @type {?{attach?: function, detach?: function, resize?: function}} */
    this._responsiveListeners = undefined;
    this._sortedMetasets = [];
    this.scales = {};
    this._plugins = new PluginService();
    this.$proxies = {};
    this._hiddenIndices = {};
    this.attached = false;
    this._animationsDisabled = undefined;
    this.$context = undefined;
    this._doResize = debounce(mode => this.update(mode), options.resizeDelay || 0);
    this._dataChanges = [];

    // Add the chart instance to the global namespace
    instances[this.id] = this;

    if (!context || !canvas) {
      // The given item is not a compatible context2d element, let's return before finalizing