figspec

Unofficial static Figma frame/file viewer available as HTML CustomElement

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import type * as Figma from "figma-js";

import { LitElement, html, property } from "lit-element";

import * as ErrorMessage from "./ErrorMessage";

import { ViewerMixin } from "./ViewerMixin";

import { SizedNode } from "./utils";

// TODO: Move docs for props in mixins (waiting for support at web-component-analyzer)
/**
 * A Figma spec viewer. Displays a rendered image alongside sizing guides.
 * @element figspec-frame-viewer
 *
 * @property {number} [panX=0]
 * Current pan offset in px for X axis.
 * This is a "before the scale" value.
 *
 * @property {number} [panY=0]
 * Current pan offset in px for Y axis.
 * This is a "before the scale" value.
 *
 * @property {number} [scale=1]
 * Current zoom level, where 1.0 = 100%.
 *
 * @property {number} [zoomSpeed=500]
 * How fast zooming when do ctrl+scroll / pinch gestures.
 * Available values: 1 ~ 1000
 * @attr [zoom-speed=500] See docs for `zoomSpeed` property.
 *
 * @property {number} [panSpeed=500]
 * How fast panning when scroll vertically or horizontally.
 * This does not affect to dragging with middle button pressed.
 * Available values: 1 ~ 1000.
 * @attr [pan-speed=500] See docs for `panSpeed` property.
 *
 * @property {Figma.Node | null} [selectedNode=null]
 * Current selected node.
 *
 * @property {number} [zoomMargin=50]
 * The minimum margin for the preview canvas in px. Will be used when the preview
 * setting a default zooming scale for the canvas.
 * @attr [zoom-margin=50] See docs for `zoomMargin` property.
 *
 * @fires scalechange When a user zoom-in or zoom-out the preview.
 * @fires positionchange When a user panned the preview.
 * @fires nodeselect When a user selected / unselected a node.
 */
export class FigspecFrameViewer extends ViewerMixin(LitElement) {
  /**
   * A response of "GET file nodes" API.
   * https://www.figma.com/developers/api#get-file-nodes-endpoint
   */
  @property({
    type: Object,
  })
  nodes: Figma.FileNodesResponse | null = null;

  /**
   * An image rendered by "GET image" API.
   * https://www.figma.com/developers/api#get-images-endpoint
   */
  @property({
    type: String,
    attribute: "rendered-image",
  })
  renderedImage: string | null = null;

  /** @private */
  get isMovable(): boolean {
    return !!(this.nodes && this.renderedImage && this.documentNode);
  }

  /**
   * Readonly. Document node (= root drawable node).
   * @readonly
   */
  get documentNode(): SizedNode | null {
    if (!this.nodes) {
      return null;
    }

    const documentNode = Object.values(this.nodes.nodes)[0];

    if (!documentNode || !("absoluteBoundingBox" in documentNode.document)) {
      return null;
    }

    return documentNode.document;
  }

  /** @private */
  get __images() {
    if (!this.documentNode || !this.renderedImage) {
      return {};
    }

    return {
      [this.documentNode.id]: this.renderedImage,
    };
  }

  /** @private */
  get error() {
    if (!this.nodes || !this.renderedImage) {
      return ErrorMessage.ErrorMessage({
        title: "Parameter error",
        children: html`<span>
          Both <code>nodes</code> and <code>rendered-image</code> are required.
        </span>`,
      });
    }

    if (!this.documentNode) {
      return ErrorMessage.ErrorMessage({
        title: "Parameter Error",
        children: html`
          <span> Document node is empty or does not have size. </span>
        `,
      });
    }

    if (super.error) {
      return super.error;
    }
  }

  getMetadata() {
    return {
      fileName: this.nodes!.name,
      timestamp: this.nodes!.lastModified,
      link: this.link,
    };
  }

  connectedCallback() {
    super.connectedCallback();

    if (this.documentNode) {
      this.__updateTree(this.documentNode);
      this.__updateEffectMargins();
      this.resetZoom();
    }
  }

  updated(changedProperties: Parameters<LitElement["updated"]>[0]) {
    super.updated(changedProperties);

    if (changedProperties.has("nodes")) {
      if (!this.documentNode) return;

      this.__updateTree(this.documentNode);
      this.resetZoom();
    }

    if (changedProperties.has("renderedImage")) {
      this.__updateEffectMargins();
    }
  }
}