fabric/dist/src/LayoutManager/ActiveSelectionLayoutManager.mjs

Object model for HTML5 canvas, and SVG-to-canvas parser. Backed by jsdom and node-canvas.

import { LayoutManager } from './LayoutManager.mjs';

/**
 * Today the LayoutManager class also takes care of subscribing event handlers
 * to update the group layout when the group is interactive and a transform is applied
 * to a child object.
 * The ActiveSelection is never interactive, but it could contain objects from
 * groups that are.
 * The standard LayoutManager would subscribe the children of the activeSelection to
 * perform layout changes to the active selection itself, what we need instead is that
 * the transformation applied to the active selection will trigger changes to the
 * original group of the children ( the one referenced under the parent property )
 * This subclass of the LayoutManager has a single duty to fill the gap of this difference.`
 */
class ActiveSelectionLayoutManager extends LayoutManager {
  subscribeTargets(context) {
    const activeSelection = context.target;
    const parents = context.targets.reduce((parents, target) => {
      target.parent && parents.add(target.parent);
      return parents;
    }, new Set());
    parents.forEach(parent => {
      parent.layoutManager.subscribeTargets({
        target: parent,
        targets: [activeSelection]
      });
    });
  }

  /**
   * unsubscribe from parent only if all its children were deselected
   */
  unsubscribeTargets(context) {
    const activeSelection = context.target;
    const selectedObjects = activeSelection.getObjects();
    const parents = context.targets.reduce((parents, target) => {
      target.parent && parents.add(target.parent);
      return parents;
    }, new Set());
    parents.forEach(parent => {
      !selectedObjects.some(object => object.parent === parent) && parent.layoutManager.unsubscribeTargets({
        target: parent,
        targets: [activeSelection]
      });
    });
  }
}

export { ActiveSelectionLayoutManager };
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