boxes_ActiveBox.js

/**
 *  File    : boxes/ActiveBox.js
 *  Created : 18/04/2015
 *  By      : Francesc Busquets <francesc@gmail.com>
 *
 *  JClic.js
 *  An HTML5 player of JClic activities
 *  https://projectestac.github.io/jclic.js
 *
 *  @source https://github.com/projectestac/jclic.js
 *
 *  @license EUPL-1.2
 *  @licstart
 *  (c) 2000-2020 Educational Telematic Network of Catalonia (XTEC)
 *
 *  Licensed under the EUPL, Version 1.1 or -as soon they will be approved by
 *  the European Commission- subsequent versions of the EUPL (the "Licence");
 *  You may not use this work except in compliance with the Licence.
 *
 *  You may obtain a copy of the Licence at:
 *  https://joinup.ec.europa.eu/software/page/eupl
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the Licence is distributed on an "AS IS" basis, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 *  Licence for the specific language governing permissions and limitations
 *  under the Licence.
 *  @licend
 *  @module
 */

/* global document */

import $ from 'jquery';
import AbstractBox from './AbstractBox.js';
import ActiveBoxContent from './ActiveBoxContent.js';
import ActiveBagContent from './ActiveBagContent.js';
import { Rectangle, Point, Container } from '../AWT.js';
import { settings, log, getMsg } from '../Utils.js';

/**
 * Objects of this class are widely used in JClic activities: cells in puzzles and associations,
 * messages and other objects are active boxes.
 *
 * The specific content, size and location of `ActiveBox` objects is determined by its
 * {@link module:boxes/ActiveBoxContent.ActiveBoxContent ActiveBoxContent} member. Most ActiveBoxes have only one content, but some of them can
 * have a secondary or "alternative" content stored in the `altContent` field. This content is
 * used only when the `alternative` flag of the ActiveBox is `on`.
 *
 * Active boxes can host video and interactive media content (specified in the `mediaContent`
 * member of the {@link module:boxes/ActiveBoxContent.ActiveBoxContent ActiveBoxContent} through its `hostedMediaPlayer` member.
 * @extends module:boxes/AbstractBox.AbstractBox
 */
export class ActiveBox extends AbstractBox {
  /**
   * ActiveBox constructor
   * @param {module:boxes/AbstractBox.AbstractBox} [parent] - The AbstractBox to which this ActiveBox belongs
   * @param {module:AWT.Container} [container] - The container where this box is placed.
   * @param {module:boxes/BoxBase.BoxBase} [boxBase] - The object where colors, fonts, border and other graphic properties
   * of this box are defined.
   * @param {number} [setIdLoc] - A numeric identifier, used to locate this box in a set of sibling objects.
   * @param {module:AWT.Rectangle} [rect] - The initial bounds of the box.
   */
  constructor(parent, container, boxBase, setIdLoc, rect) {
    // ActiveBox extends AbstractBox
    super(parent, container, boxBase);
    this.clear();
    if (typeof setIdLoc === 'number') {
      this.idLoc = setIdLoc;
      this.idAss = 0;
      this.idOrder = 0;
    }
    if (rect)
      this.setBounds(rect);
  }

  /**
   * Factory constructor that creates a new cell inside a JQuery DOM element.
   * @param {external:jQuery} $dom - The DOM element that will act as a container
   * @param {module:boxes/ActiveBoxContent.ActiveBoxContent} abc - The cell's content. Must not be null and have the `dimension`
   * member initialized.
   * @returns {module:boxes/ActiveBox.ActiveBox}
   */
  static createCell($dom, abc) {
    if (abc && abc.dimension) {
      const
        box = new ActiveBox(),
        $canvas = $('<canvas width="' + abc.dimension.width + '" height="' + abc.dimension.height + '"/>'),
        rect = new Rectangle(0, 0, abc.dimension.width, abc.dimension.height);
      box.container = new Container();
      box.container.$div = $dom;
      box.setContent(abc);
      box.setBounds(rect);
      $dom.append($canvas);
      // Create accessible, focusable elements only for cells with media content
      // TODO: remove focus mark on blur in cells placed on fillInBlanks activities
      if (abc.mediaContent)
        box.buildAccessibleElement($canvas, $dom);
      box.update($canvas.get(-1).getContext('2d'), rect);
      return box;
    }
  }

  /**
   * Returns the current content used by the box
   * @returns {module:boxes/ActiveBoxContent.ActiveBoxContent}
   */
  getCurrentContent() {
    return this.isAlternative() ? this.altContent : this.content;
  }

  /**
   * Returns the current content, creating an empty one if needed.
   * @returns {module:boxes/ActiveBoxContent.ActiveBoxContent}
   */
  getContent() {
    if (!this.content)
      this.setContent(new ActiveBoxContent());
    return this.content;
  }

  /**
   * Clears the current content
   */
  clear() {
    this.content = null;
    this.altContent = null;
    this.idOrder = -1;
    this.setInactive(true);
    if (!this.hasHostedComponent)
      this.setHostedComponent(null);
    this.setHostedMediaPlayer(null);
    if (this.$accessibleElement)
      this.$accessibleElement.html('');
    if (this.tmpTrans)
      this.tmpTrans = false;
    this.invalidate();
  }

  /**
   * Checks if two ActiveBox objects have equivalent content
   * @param {module:boxes/ActiveBox.ActiveBox} bx - The ActiveBox to check against this.
   * @param {boolean} [checkCase] - When `true`, the comparing will be case-sensitive.
   * @returns {boolean} - `true` if both cells are equivalent.
   */
  isEquivalent(bx, checkCase) {
    return bx !== null &&
      this.content !== null &&
      this.content.isEquivalent(bx.content, checkCase);
  }

  /**
   * Same functionality as {@link module:boxes/ActiveBox.ActiveBox#isEquivalent isEquivalent}, but comparing the current content.
   * @param {module:boxes/ActiveBox.ActiveBox} bx - The ActiveBox to check against this.
   * @param {boolean} [checkCase] - When `true`, the comparing will be case-sensitive.
   * @returns {boolean}
   */
  isCurrentContentEquivalent(bx, checkCase) {
    return bx !== null &&
      this.getCurrentContent() !== null &&
      this.getCurrentContent().isEquivalent(bx.getCurrentContent(), checkCase);
  }

  /**
   * Swaps the location of two active boxes
   * @param {module:boxes/ActiveBox.ActiveBox} bx - The ActiveBox to swap with this one.
   */
  exchangeLocation(bx) {
    const
      pt = new Point(this.pos),
      idLoc0 = this.idLoc;
    this.moveTo(bx.pos);
    bx.moveTo(pt);
    this.idLoc = bx.idLoc;
    bx.idLoc = idLoc0;
  }

  /**
   * Copy the content of another ActiveBox into this one
   * @param {module:boxes/ActiveBox.ActiveBox} bx - The ActiveBox from which to take the content
   */
  copyContent(bx) {
    this.idOrder = bx.idOrder;
    this.idAss = bx.idAss;
    this.content = bx.content;
    this.altContent = bx.altContent;
    if (this.content) {
      if (this.content.style)
        this.setBoxBase(this.content.style);
      if (this.content.border !== null && bx.hasBorder() !== this.content.border)
        this.setBorder(this.content.border);
    }
    this.setInactive(bx.isInactive());
    this.setInverted(bx.isInverted());
    this.setAlternative(bx.isAlternative());
    this.setHostedComponent(bx.getHostedComponent());
    this.hasHostedComponent = bx.hasHostedComponent;
    this.setHostedMediaPlayer(bx.hostedMediaPlayer);
    if (this.hostedMediaPlayer)
      this.hostedMediaPlayer.setVisualComponentVisible(!this.isInactive() && this.isVisible());
    if (this.$accessibleElement)
      this.$accessibleElement.html(this.toString());
  }

  /**
   *
   * Exhanges the content of this ActiveBox with another one
   * @param {module:boxes/ActiveBox.ActiveBox} bx - The ActiveBox with which to exchange the content.
   */
  exchangeContent(bx) {
    const bx0 = new ActiveBox(this.getParent(), this.getContainerX(), this.boxBase);
    bx0.copyContent(this);
    this.copyContent(bx);
    bx.copyContent(bx0);
  }

  /**
   *
   * Sets the text content of this ActiveBox.
   * @param {string} tx - The text to set.
   */
  setTextContent(tx) {
    // only plain text!
    if (!tx)
      tx = '';
    if (!this.content)
      this.content = new ActiveBoxContent();
    this.content.text = tx;
    this.content.mediaContent = null;
    this.content.img = null;

    this.setHostedComponent(null);
    this.setInactive(false);
    this.checkHostedComponent();
    this.setHostedMediaPlayer(null);

    if (this.$accessibleElement)
      this.$accessibleElement.html(this.toString());
  }

  /**
   * Sets the default value to `idAss`
   */
  setDefaultIdAss() {
    this.idAss = this.content === null ? -1 : this.content.id;
  }

  /**
   * Checks if this ActiveBox is at its original place.
   * @returns {boolean}
   */
  isAtPlace() {
    return this.idOrder === this.idLoc;
  }

  /**
   * Sets the {@link module:boxes/ActiveBoxContent.ActiveBoxContent ActiveBoxContent} of this ActiveBox
   * @param {ActiveBoxContent|ActiveBagContent} abc - Object containing the content to set.
   * @param {number} i - When `abc` is an {@link module:boxes/ActiveBagContent.ActiveBagContent ActiveBagContent}, this field indicates an
   * index in the content array.
   */
  setContent(abc, i) {
    if (abc instanceof ActiveBagContent) {
      if (i < 0)
        i = this.idOrder;
      if (i >= abc.getNumCells())
        return;
      if (abc.style !== this.boxBase)
        this.setBoxBase(abc.style);

      // `abc` is now an [ActiveBoxContent](ActiveBoxContent.html)
      abc = abc.getActiveBoxContent(i);
    }
    this.setHostedComponent(null);
    this.setHostedMediaPlayer(null);
    this.content = abc;
    if (abc) {
      if (abc.animatedGifFile && !this.specialShape) {
        const url = `url(${abc.animatedGifFile})`;
        const $hc = $('<span/>').css({
          'background-image': url,
          'background-position': 'center',
          'background-repeat': 'no-repeat'
        });
        // Save background image for later use
        $hc.data('background-image', url);

        if (abc.imgClip !== null) {
          $hc.css({
            'background-origin': 'border-box',
            'background-position': `${-abc.imgClip.pos.x}px ${-abc.imgClip.pos.y}px`
            // TODO: Use background-size only when the original image must be compressed
            //,'background-size': abc.imgClip.dim.width + 'px ' + abc.imgClip.dim.height + 'px'
          });
        }
        this.setHostedComponent($hc);
      }

      if (abc.style !== this.boxBase)
        this.setBoxBase(abc.style);

      if (abc.innerHtmlText)
        this.setHostedComponent($('<div/>').html(abc.innerHtmlText));

      if (abc.hasOwnProperty('border') && this.hasBorder() !== abc.border)
        this.setBorder(abc.border);
      this.setInactive(false);
      if (abc.amp)
        this.setHostedMediaPlayer(abc.amp);
      this.checkHostedComponent();
      this.checkAutoStartMedia();
    } else
      this.clear();

    this.invalidate();
    if (this.$accessibleElement)
      this.$accessibleElement.html(this.toString());
  }

  /**
   * Sets the {@link module:boxes/ActiveBoxContent.ActiveBoxContent ActiveBoxContent} that will act as an alternative content (`altContent` field)
   * of this ActiveBox,
   * @param {ActiveBoxContent|ActiveBagContent} abc - Object containing the content to set.
   * @param {number} i - When `abc` is an {@link module:boxes/ActiveBagContent.ActiveBagContent ActiveBagContent}, this field indicates an
   * index in the content array.
   */
  setAltContent(abc, i) {
    if (abc instanceof ActiveBagContent) {
      if (i < 0)
        i = this.idOrder;
      // `abc` is now an [ActiveBoxContent](ActiveBoxContent.html)
      abc = abc.getActiveBoxContent(i);
    }
    this.altContent = abc;
    this.checkHostedComponent();
    if (this.isAlternative() && this.hostedMediaPlayer)
      this.setHostedMediaPlayer(null);

    if (this.$accessibleElement) {
      this.$accessibleElement.html(this.toString());
      this.$accessibleElement.prop('disabled', true);
    }
  }

  /**
   * Sets the current content of this ActiveBox
   * @param {module:boxes/ActiveBoxContent.ActiveBoxContent} abc - The content to set.
   */
  setCurrentContent(abc) {
    if (this.isAlternative())
      this.setAltContent(abc);
    else
      this.setContent(abc);
    this.invalidate();
  }

  /**
   * Puts this ActiveBox in "alternative" mode, meaning that `altContent` will be used instead of `content`
   */
  switchToAlt() {
    if (this.isAlternative() || !this.altContent || this.altContent.isEmpty())
      return false;
    this.setHostedComponent(null);
    this.setHostedMediaPlayer(null);
    this.setAlternative(true);
    this.tmpTrans = false;
    this.checkHostedComponent();
    this.checkAutoStartMedia();

    if (this.$accessibleElement)
      this.$accessibleElement.html(this.toString());

    return true;
  }

  /**
   * Checks the presence of content susceptible to be treated as HTML DOM embedded in this ActiveBox.
   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Drawing_DOM_objects_into_a_canvas}
   */
  checkHostedComponent() {
    if (this.hasHostedComponent)
      return;
    const
      abc = this.getCurrentContent(),
      style = this.getBoxBaseResolve();
    if (!this.isInactive() && abc && abc.innerHtmlText)
      style.getCSS()['text-align'] = abc.txtAlign.h.replace('middle', 'center');
  }

  /**
   * Checks if the call has a {@link module:media/MediaContent.MediaContent} set to `autostart`, and launches it when found.
   */
  checkAutoStartMedia() {
    const cnt = this.getContent();
    if (cnt && cnt.mediaContent && cnt.mediaContent.autoStart && cnt.amp) {
      cnt.amp.playNow(this);
    }
  }

  /**
   * Draws the content of this Activebox on the specified canvas context.
   * @override
   * @param {external:CanvasRenderingContext2D} ctx - The canvas rendering context used to draw the
   * box content.
   * @param {module:AWT.Rectangle} [dirtyRegion] - The area that must be repainted. `null` refers to the whole box.
   */
  updateContent(ctx, dirtyRegion) {

    const
      abc = this.getCurrentContent(),
      style = this.getBoxBaseResolve();

    if (this.isInactive() || !abc || this.dim.width < 2 || this.dim.height < 2) {
      this._focusAccessibleElement(ctx);
      return true;
    }

    if (dirtyRegion && !this.intersects(dirtyRegion))
      return false;

    let imgRect = null;

    if (abc.img && !this.tmpTrans) {
      try {
        if (abc.imgClip) {
          const r = abc.imgClip.getBounds();
          let img = abc.img;
          if (!abc.imgClip.isRect()) {
            // Prepare a temporary `canvas` object that will contain the clipped image
            const tmpCanvas = document.createElement('canvas');
            tmpCanvas.width = r.pos.x + r.dim.width;
            tmpCanvas.height = r.pos.y + r.dim.height;
            const tmpCtx = tmpCanvas.getContext('2d');
            // Set the clipping region
            abc.imgClip.clip(tmpCtx);
            // Draw the original image
            tmpCtx.drawImage(abc.img, 0, 0);
            // Use the temporary canvas as a source image
            // (as seen on: [http://stackoverflow.com/questions/7242006/html5-copy-a-canvas-to-image-and-back])
            img = tmpCanvas;
          }
          ctx.drawImage(img,
            Math.max(0, r.pos.x), Math.max(0, r.pos.y), Math.min(img.width, r.dim.width), Math.min(img.height, r.dim.height),
            this.pos.x, this.pos.y, this.dim.width, this.dim.height);
        } else {
          let
            imgw = abc.img.naturalWidth || this.dim.width,
            imgh = abc.img.naturalHeight || this.dim.height,
            compress = false,
            scale = 1.0;
          if (settings.COMPRESS_IMAGES &&
            (this.dim.width > 0 && this.dim.height > 0) &&
            (imgw > this.dim.width || imgh > this.dim.height)) {

            scale = Math.min(this.dim.width / imgw, this.dim.height / imgh);
            imgw *= scale;
            imgh *= scale;
            compress = true;
          }
          const xs = abc.imgAlign.h === 'left' ? 0
            : abc.imgAlign.h === 'right' ? this.dim.width - imgw
              : (this.dim.width - imgw) / 2;
          const ys = abc.imgAlign.v === 'top' ? 0
            : abc.imgAlign.v === 'bottom' ? this.dim.height - imgh
              : (this.dim.height - imgh) / 2;
          if (compress) {
            ctx.drawImage(abc.img, this.pos.x + xs, this.pos.y + ys, imgw, imgh);
          } else
            ctx.drawImage(abc.img, this.pos.x + xs, this.pos.y + ys);

          if (abc.avoidOverlapping && abc.text)
            imgRect = new Rectangle(
              Math.max(0, xs), Math.max(0, ys),
              Math.min(this.dim.width, imgw), Math.min(this.dim.height, imgh));
        }
      } catch (ex) {
        log('warn', `Unable to draw image "${abc.image}": ${ex.message}`);
      }
    }
    if (abc.text && abc.text.length > 0) {
      let
        px = this.pos.x,
        py = this.pos.y,
        pWidth = this.dim.width,
        pHeight = this.dim.height;

      if (imgRect) {
        // There is an image in the ActiveBox
        // Try to compute the current space available for text
        const
          prx = [0, imgRect.pos.x, imgRect.pos.x + imgRect.dim.width, pWidth],
          pry = [0, imgRect.pos.y, imgRect.pos.y + imgRect.dim.height, pHeight],
          rr = [
            // Calc four rectangles inside BoxBag, sourronding imgRect
            // Top rectangle:
            new Rectangle(prx[0], pry[0], prx[3], pry[1]),
            // Bottom rectangle:
            new Rectangle(prx[0], pry[2], prx[3], pry[3] - pry[2]),
            // Left rectangle:
            new Rectangle(prx[0], pry[0], prx[1], pry[3]),
            // Right rectangle:
            new Rectangle(prx[2], pry[0], prx[3] - prx[2], pry[3])
          ];
        //
        // Find the rectangle with highest surface, and in accordance
        // with the `txtAlign` values of the current
        // [ActiveBoxContent](ActiveBoxContent)
        let rmax = rr[0];
        let maxSurface = rmax.dim.width * rmax.dim.height;
        for (let i = 1; i < rr.length; i++) {
          let s = rr[i].dim.width * rr[i].dim.height;
          if (s > maxSurface - 1) {
            if (Math.abs(s - maxSurface) <= 1) {
              let b = false;
              switch (i) {
                case 1:
                  b = abc.txtAlign.v === 'bottom';
                  break;
                case 2:
                  b = abc.txtAlign.h === 'left';
                  break;
                case 3:
                  b = abc.txtAlign.h === 'right';
                  break;
              }
              if (!b)
                continue;
            }
            maxSurface = s;
            rmax = rr[i];
          }
        }
        // Finally, this is the surface available to draw text:
        px += rmax.pos.x;
        py += rmax.pos.y;
        pWidth = rmax.dim.width;
        pHeight = rmax.dim.height;
      }

      // Calc available width and height, discounting margins
      const
        availWidth = Math.max(5, pWidth - 2 * style.textMargin),
        availHeight = Math.max(5, pHeight - 2 * style.textMargin);

      // Calc the size of each line
      const lines = style.prepareText(ctx, abc.text, availWidth, availHeight);

      ctx.font = style.font.cssFont();
      ctx.textBaseline = 'alphabetic';
      const
        lineHeight = style.font.getHeight(),
        totalHeight = lineHeight * lines.length;

      // Calc the vertical co-ordinate of the first line
      // Default is 'middle'
      let y = py + style.textMargin + (abc.txtAlign.v === 'top' ? 0
        : abc.txtAlign.v === 'bottom' ? availHeight - totalHeight
          : (availHeight - totalHeight) / 2) + style.font.getMetrics().ascent;

      for (let l = 0; l < lines.length; l++, y += lineHeight) {
        // Calc the horizontal position of each line
        // Default is 'middle'
        const x = px + style.textMargin + (abc.txtAlign.h === 'left' ? 0
          : abc.txtAlign.h === 'right' ?
            availWidth - lines[l].size.width
            : (availWidth - lines[l].size.width) / 2);

        if (style.shadow) {
          // Render text shadow
          const d = Math.max(1, style.font.size / 10);
          ctx.fillStyle = style.shadowColor;
          ctx.fillText(lines[l].text, x + d, y + d);
        }
        // Render text
        ctx.fillStyle = this.isInverted() ? style.backColor
          : this.isAlternative() ? style.alternativeColor : style.textColor;
        ctx.fillText(lines[l].text, x, y);
      }

      this._focusAccessibleElement(ctx);

    }
    return true;
  }

  /**
   * Draw focus on accessible element if needed
   * @param {external:CanvasRenderingContext2D} ctx - The canvas rendering context used to draw the
   * box content.
   */
  _focusAccessibleElement(ctx) {
    if (settings.CANVAS_DRAW_FOCUS && this.$accessibleElement) {
      this.shape.preparePath(ctx);
      ctx.drawFocusIfNeeded(this.$accessibleElement.get(-1));
    }
  }


  /**
   * Gets the `description` field of the current {@link module:boxes/ActiveBoxContent.ActiveBoxContent ActiveBoxContent}
   * @returns {string}
   */
  getDescription() {
    return this.content ? this.content.getDescription() : '';
  }

  /**
   * Gets a descriptive text for this ActiveBox
   * @returns {string}
   */
  toString() {
    return (this.role !== 'cell' ? getMsg(this.role) : '') + (this.getCurrentContent() || '-').toString();
  }

  /**
   * Plays the action or media associated with this ActiveBox
   * @param {module:JClicPlayer.JClicPlayer} ps - Usually, a {@link module:JClicPlayer.JClicPlayer JClicPlayer}
   * @param {function[]} delayedActions - If set, store the the action in this array for future execution
   */
  playMedia(ps, delayedActions = null) {
    const abc = this.getCurrentContent();
    if (abc && abc.mediaContent) {
      log('debug', `Playing: ${abc.mediaContent.toString()}`);
      ps.playMedia(abc.mediaContent, this, delayedActions);
      return true;
    }
    return false;
  }

  /**
   * Sets the hosted media player of this ActiveBox
   * @param {module:media/ActiveMediaPlayer.ActiveMediaPlayer} amp - The media player.
   */
  setHostedMediaPlayer(amp) {
    const old = this.hostedMediaPlayer;
    this.hostedMediaPlayer = amp;
    if (old && old !== amp)
      old.linkTo(null);
    if (amp)
      amp.linkTo(this);
  }

  /**
   * Sets a new size and/or dimension to this box.
   * @override
   * @param {AWT.Rectangle|number} rect - An AWT.Rectangle object, or the `x` coordinate of the
   * upper-left corner of a new rectangle.
   * @param {number} [y] - `y` coordinate of the upper-left corner of the new rectangle.
   * @param {number} [w] - Width of the new rectangle.
   * @param {number} [h] - Height of the new rectangle.
   */
  setBounds(rect, y, w, h) {
    if (typeof rect === 'number')
      // arguments are co-ordinates and size
      rect = new Rectangle(rect, y, w, h);
    // Rectangle comparision
    if (this.equals(rect))
      return;
    super.setBounds(rect);
    if (this.hostedMediaPlayer)
      this.hostedMediaPlayer.checkVisualComponentBounds(this);
  }

  /**
   * Places and resizes {@link module:boxes/AbstractBox.AbstractBox#$hostedComponent $hostedComponent}, based on the size
   * and position of this box.
   * @override
   * @param {boolean} sizeChanged - `true` when this {@link module:boxes/ActiveBox.ActiveBox ActiveBox} has changed its size
   */
  setHostedComponentBounds(sizeChanged) {
    if (this.$hostedComponent) {
      super.setHostedComponentBounds(sizeChanged);
      const abc = this.getCurrentContent();
      if (sizeChanged && abc && abc.animatedGifFile && abc.img) {
        const
          img = abc.img,
          w = Math.max(img.naturalWidth, this.dim.width),
          h = Math.max(img.naturalHeight, this.dim.height);
        let scale = 1, bgSize = '';
        if (abc.imgClip) {
          const r = abc.imgClip.getBounds();
          if (this.dim.width < r.dim.width || this.dim.height < r.dim.height) {
            scale = Math.min(this.dim.width / r.dim.width, this.dim.height / r.dim.height);
            bgSize = `${w * scale}px ${h * scale}px`;
          }
          this.$hostedComponent.css({
            'background-position': `${-abc.imgClip.pos.x * scale}px ${-abc.imgClip.pos.y * scale}px`,
            'background-size': bgSize
          });
        } else {
          if (this.dim.width < w || this.dim.height < h) {
            scale = Math.min(this.dim.width / w, this.dim.height / h);
            bgSize = `${w * scale}px ${h * scale}px`;
          }
          this.$hostedComponent.css({
            'background-size': bgSize
          });
        }
      }
    }
  }

  /**
   * Builds a hidden `buton` that will act as a accessible element associated to the canvas area
   * of this ActiveBox.
   * The button will be created only when `CanvasRenderingContext2D` has a method named `addHitRegion`.
   * See https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Hit_regions_and_accessibility
   * for more information and supported browsers.
   * @param {external:jQuery} $canvas - The `canvas` where this `ActiveBox` will deploy, wrapped up in a jQuery object
   * @param {external:jQuery} $clickReceiver - The DOM element that will be notified  when `$accessibleElement` is activated.
   * @param {external:jQuery} [$canvasGroup] - Optional DOM element containing the accessible element. Useful to group cells in associations. When `null`, the element belongs to $canvas.
   * @param {string} [eventType] - Type of event sent to $clickReceiver. Default is `click`.
   * @returns {external:jQuery} - The accessible element associated to this ActiveBox.
   */
  buildAccessibleElement($canvas, $clickReceiver, $canvasGroup, eventType) {
    if (this.$accessibleElement)
      this.$accessibleElement.remove();

    const canvas = $canvas.get(-1);
    if (canvas.width > 0 && canvas.height > 0) {
      const
        id = Math.round(Math.random() * 100000),
        disabled = this.isInactive() && !this.accessibleAlwaysActive;
      this.$accessibleElement = $('<button/>', {
        tabindex: disabled ? -1 : 0,
        id: `AE${id}`,
        disabled: disabled
      })
        .html(this.toString())
        .on('click', ev => {
          // Check if event was produced by a mouse click
          if (ev.originalEvent && (ev.originalEvent.pageX !== 0 || ev.originalEvent.pageY !== 0)) {
            // Mouse clicks should be processed odirectly by the canvas, so ignore this accessible event
            return true;
          }
          log('debug', `Click on accessible element: ${this.toString()}`);
          const
            $event = $.Event(eventType || 'click'),
            bounds = this.getBounds(),
            offset = $canvas.offset();
          $event.pageX = offset.left + bounds.pos.x + bounds.dim.width / 2;
          $event.pageY = offset.top + bounds.pos.y + bounds.dim.height / 2;
          $clickReceiver.trigger($event);
          return false;
        });
      const $dest = $canvasGroup || $canvas;
      $dest.append(this.$accessibleElement);
      if (settings.CANVAS_DRAW_FOCUS) {
        this.$accessibleElement.on('focus blur', ev => {
          log('debug', `${ev.type} accessible element: ${this.toString()}`);
          if (this.container)
            this.container.update();
          this.updateContent(canvas.getContext('2d'), null);
        });
      }
    }
    return this.$accessibleElement;
  }
}

Object.assign(ActiveBox.prototype, {
  /**
   * Identifier used to set the relative position of this box in a set.
   * @name module:boxes/ActiveBox.ActiveBox#idOrder
   * @type {number} */
  idOrder: -1,
  /**
   * Identifier used to set a relative position in the space.
   * @name module:boxes/ActiveBox.ActiveBox#idLoc
   * @type {number} */
  idLoc: -1,
  /**
   * Identifier used to establish relationships between cells of different sets (in associations)
   * @name module:boxes/ActiveBox.ActiveBox#idAss
   * @type {number} */
  idAss: -1,
  /**
   * Backup of the original position of the cell, useful when the real position must be restored after a temporary change.
   * @name module:boxes/ActiveBox.ActiveBox#pos0
   * @type {module:AWT.Point} */
  pos0: null,
  /**
   * Main content of this box
   * @name module:boxes/ActiveBox.ActiveBox#content
   * @type {module:boxes/ActiveBoxContent.ActiveBoxContent} */
  content: null,
  /**
   * Alternative content of this box
   * @name module:boxes/ActiveBox.ActiveBox#altContent
   * @type {module:boxes/ActiveBoxContent.ActiveBoxContent} */
  altContent: null,
  /**
   * Flag to check if this box has a 'hosted component'
   * @name module:boxes/ActiveBox.ActiveBox#hostedComponent
   * @type {boolean} */
  hasHostedComponent: false,
  /**
   * The media player associated to this box
   * @name module:boxes/ActiveBox.ActiveBox#hostedMediaPlayer
   * @type {module:media/ActiveMediaPlayer.ActiveMediaPlayer} */
  hostedMediaPlayer: null,
  /**
   * Indicates that this box is used as a background. When drawing, the clipping region must be respected.
   * @name module:boxes/ActiveBox.ActiveBox#isBackground
   * @type {boolean} */
  isBackground: false,
});

export default ActiveBox;