@finos/legend-extension-dsl-diagram/src/components/DiagramRenderer.ts

Legend extension for Diagram DSL

/**
 * Copyright (c) 2020-present, Goldman Sachs
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {
  uuid,
  noop,
  UnsupportedOperationError,
  IllegalStateError,
  guaranteeNonNullable,
  findLast,
  uniqBy,
} from '@finos/legend-shared';
import {
  type AbstractProperty,
  Class,
  Enumeration,
  PrimitiveType,
  DerivedProperty,
  PackageableElementExplicitReference,
  PropertyExplicitReference,
  GenericTypeExplicitReference,
  GenericType,
  Property,
  Multiplicity,
  getAllSuperclasses,
  getAllOwnClassProperties,
  generateMultiplicityString,
  getRawGenericType,
  AggregationKind,
} from '@finos/legend-graph';
import { action, makeObservable, observable } from 'mobx';
import type { Diagram } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_Diagram.js';
import { Rectangle } from '../graph/metamodel/pure/packageableElements/diagram/geometry/DSL_Diagram_Rectangle.js';
import { Point } from '../graph/metamodel/pure/packageableElements/diagram/geometry/DSL_Diagram_Point.js';
import { PositionedRectangle } from '../graph/metamodel/pure/packageableElements/diagram/geometry/DSL_Diagram_PositionedRectangle.js';
import { ClassView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_ClassView.js';
import type { PropertyHolderView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_PropertyHolderView.js';
import { GeneralizationView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_GeneralizationView.js';
import { RelationshipView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_RelationshipView.js';
import { PropertyView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_PropertyView.js';
import {
  boxContains,
  buildBottomRightCornerBox,
  getBottomRightCornerPoint,
  getElementPosition,
  rotatePointX,
  rotatePointY,
} from '../graph/helpers/DSL_Diagram_Helper.js';
import { AssociationView } from '../graph/metamodel/pure/packageableElements/diagram/DSL_Diagram_AssociationView.js';
import {
  class_addProperty,
  class_addSuperType,
} from '@finos/legend-application-studio';
import {
  classView_setHideProperties,
  classView_setHideStereotypes,
  classView_setHideTaggedValues,
  diagram_addClassView,
  diagram_addGeneralizationView,
  diagram_addPropertyView,
  diagram_deleteAssociationView,
  diagram_deleteClassView,
  diagram_deleteGeneralizationView,
  diagram_deletePropertyView,
  diagram_setAssociationViews,
  diagram_setClassViews,
  diagram_setGeneralizationViews,
  diagram_setPropertyViews,
  findOrBuildPoint,
  positionedRectangle_forceRefreshHash,
  positionedRectangle_setPosition,
  positionedRectangle_setRectangle,
  relationshipEdgeView_setOffsetX,
  relationshipEdgeView_setOffsetY,
  relationshipView_changePoint,
  relationshipView_simplifyPath,
  relationshipView_setPath,
} from '../stores/studio/DSL_Diagram_GraphModifierHelper.js';

export enum DIAGRAM_INTERACTION_MODE {
  LAYOUT,
  PAN,
  ZOOM_IN,
  ZOOM_OUT,
  ADD_RELATIONSHIP,
  ADD_CLASS,
}

export enum DIAGRAM_RELATIONSHIP_EDIT_MODE {
  // ASSOCIATION,
  PROPERTY,
  INHERITANCE,
  NONE,
}

export enum DIAGRAM_ALIGNER_OPERATOR {
  ALIGN_LEFT,
  ALIGN_CENTER,
  ALIGN_RIGHT,
  ALIGN_TOP,
  ALIGN_MIDDLE,
  ALIGN_BOTTOM,
  SPACE_HORIZONTALLY,
  SPACE_VERTICALLY,
}

const MIN_ZOOM_LEVEL = 0.05; // 5%
const FIT_ZOOM_PADDING = 10;
export const DIAGRAM_ZOOM_LEVELS = [
  50, 75, 90, 100, 110, 125, 150, 200, 250, 300, 400,
];

const getPropertyDisplayName = (property: AbstractProperty): string =>
  (property instanceof DerivedProperty ? '/ ' : '') + property.name;

export class DiagramRenderer {
  diagram: Diagram;

  isReadOnly: boolean;
  enableLayoutAutoAdjustment: boolean;

  div: HTMLDivElement;
  canvas: HTMLCanvasElement;
  ctx: CanvasRenderingContext2D;

  // Rendering elements
  canvasDimension: Rectangle; // dimension of the canvas, i.e. the dimension of the container element that hosts the canvas
  canvasCenter: Point;
  /**
   * The screen or artboard that contains all parts of the diagram. It's important to understand that this is indeed a virtual screen
   * because it is constructed by constructing the smallest possible bounding rectangle around the diagram. As such, information about
   * the screen is not persisted (in the protocol JSON)
   */
  virtualScreen: PositionedRectangle;
  /**
   * This refers the offset of the virtual screen with respect to the canvas. We have 2 types of coordinate:
   * `stored` (in the JSON protocol of class and relationship views) vs. `rendering`.
   *
   * There are 2 important facts about stored coordinates:
   * 1. Zoom is not taken into account (unlike rendering coordinates which change as we zoom)
   * 2. They are with respect to the canvas, not the screen (because the screen is virtual - see above)
   *
   * As such, when we debug, let's say we have a position (x,y), if we want to find that coordinate in the coordiante system of the canvas, we have to
   * add the offset, so the coordinate of (x, y) is (x + screenOffset.x, y + screenOffset.y) when we refer to the canvas coordinate system
   * So if we turn on debug mode and try to move the top left corner of the screen to the `offset crosshair` the screen coordinate system should align
   * with the canvas coordinate system. Of course due to centering and moving the screen around there is still an offset between the 2 coordinate system,
   * but we know for a fact that the top left of the screen will have stored coordinate (0,0)
   */
  screenOffset: Point;
  zoom: number;

  // edit modes
  // NOTE: we keep the edit mode separated like this
  // becase we anticipate more complex interactions in the future
  interactionMode: DIAGRAM_INTERACTION_MODE;
  relationshipMode: DIAGRAM_RELATIONSHIP_EDIT_MODE;

  // UML specific shapes
  triangle: [Point, Point, Point];
  diamond: [Point, Point, Point, Point];

  // Font
  fontFamily: string;
  fontSize: number;
  lineHeight: number;

  // Wrap text
  truncateText: boolean;
  maxLineLength: number;
  // TODO: we might want to do text wrapping as well

  // Spacing
  screenPadding: number; // the padding of the diagram (art board)
  classViewSpaceX: number;
  classViewSpaceY: number;
  propertySpacing: number;

  // Screen Grid (for debugging)
  showScreenGrid: boolean; // show the screen coordinate system
  showScreenBoxGuide: boolean; // show the screen border box and center
  screenGridAxisTickLength: number;
  screenGridSpacingX: number;
  screenGridSpacingY: number;
  screenGridLineWidth: number;
  screenGridLineColor: string;
  screenGridLabelTextColor: string;
  screenGuideLineColor: string;
  screenGuideLabelTextColor: string;

  // Canvas Grid (for debugging)
  showCanvasGrid: boolean; // show the canvas coordinate system
  showCanvasBoxGuide: boolean; // show the canvas border box and center
  showScreenOffsetGuide: boolean; // show the offset of the screen with respect to the canvas
  canvasGridAxisTickLength: number;
  canvasGridSpacingX: number;
  canvasGridSpacingY: number;
  canvasGridLineWidth: number;
  canvasGridLineColor: string;
  canvasGridLabelTextColor: string;
  canvasGuideLineColor: string;
  canvasGuideLabelTextColor: string;
  screenOffsetGuideLineColor: string;
  screenOffsetGuideLabelTextColor: string;

  // Line
  defaultLineWidth: number;

  // Color
  defaultLineColor: string;
  canvasColor: string;
  backgroundColor: string;
  classViewFillColor: string;
  classViewHeaderTextColor: string;
  classViewPropertyTextColor: string;
  classViewPrimitivePropertyTextColor: string;
  classViewDerivedPropertyTextColor: string;
  relationshipViewTextColor: string;
  propertyViewOwnedDiamondColor: string;
  propertyViewSharedDiamondColor: string;
  generalizationViewInheritanceTriangeFillColor: string;
  selectionBoxBorderColor: string;

  // Selection
  selection?: PositionedRectangle | undefined;
  selectionStart?: Point | undefined;
  selectedClassCorner?: ClassView | undefined; // the class view which we currently select the bottom right corner
  selectedClassProperty?:
    | { property: AbstractProperty; selectionPoint: Point }
    | undefined;
  selectedClasses: ClassView[];
  selectedPropertyOrAssociation?: PropertyHolderView | undefined;
  selectedInheritance?: GeneralizationView | undefined;
  selectedPoint?: Point | undefined;

  private _selectedClassesInitialPositions: {
    classView: ClassView;
    oldPos: Point;
  }[];

  // Relationship
  startClassView?: ClassView | undefined;
  handleAddRelationship?:
    | ((start: ClassView, target: ClassView) => RelationshipView | undefined)
    | undefined;

  mouseOverClassCorner?: ClassView | undefined;
  mouseOverClassName?: ClassView | undefined;
  mouseOverClassView?: ClassView | undefined;
  mouseOverClassProperty?: AbstractProperty | undefined;
  mouseOverPropertyHolderViewLabel?: PropertyHolderView | undefined;
  cursorPosition: Point;

  leftClick: boolean;
  middleClick: boolean;
  rightClick: boolean;
  clickX: number;
  clickY: number;
  positionBeforeLastMove: Point;

  // interactions
  onAddClassViewClick: (point: Point) => void = noop();
  onClassViewRightClick: (classView: ClassView, point: Point) => void = noop();

  onBackgroundDoubleClick?: ((point: Point) => void) | undefined;
  onClassViewDoubleClick?:
    | ((classView: ClassView, point: Point) => void)
    | undefined;
  onClassNameDoubleClick?:
    | ((classView: ClassView, point: Point) => void)
    | undefined;
  onClassPropertyDoubleClick?:
    | ((
        property: AbstractProperty,
        point: Point,
        propertyHolderView: PropertyHolderView | undefined,
      ) => void)
    | undefined;

  handleEditClassView: (classView: ClassView) => void = noop();
  handleEditProperty: (
    property: AbstractProperty,
    point: Point,
    propertyHolderView: PropertyHolderView | undefined,
  ) => void = noop();
  handleAddSimpleProperty: (classView: ClassView) => void = noop();

  constructor(div: HTMLDivElement, diagram: Diagram) {
    makeObservable(this, {
      isReadOnly: observable,
      enableLayoutAutoAdjustment: observable,
      interactionMode: observable,
      relationshipMode: observable,
      zoom: observable,
      mouseOverClassView: observable,
      mouseOverClassName: observable,
      mouseOverClassCorner: observable,
      mouseOverClassProperty: observable,
      mouseOverPropertyHolderViewLabel: observable,
      selectionStart: observable,
      selectedClassCorner: observable,
      selectedClasses: observable,
      selectedPropertyOrAssociation: observable,
      selectedInheritance: observable,
      leftClick: observable,
      middleClick: observable,
      rightClick: observable,
      changeMode: action,
      setIsReadOnly: action,
      setEnableLayoutAutoAdjustment: action,
      setMouseOverClassView: action,
      setMouseOverClassName: action,
      setMouseOverClassCorner: action,
      setMouseOverClassProperty: action,
      setMouseOverPropertyHolderViewLabel: action,
      setSelectionStart: action,
      setSelectedClassCorner: action,
      setSelectedClasses: action,
      setSelectedPropertyOrAssociation: action,
      setSelectedInheritance: action,
      setLeftClick: action,
      setMiddleClick: action,
      setRightClick: action,
      setZoomLevel: action,
      align: action,
    });

    this.diagram = diagram;

    // Container and canvas
    this.div = div;
    this.div.childNodes.forEach((node) => this.div.removeChild(node)); // Clear the <div> container
    this.canvas = document.createElement('canvas');
    this.canvasDimension = new Rectangle(
      this.div.offsetWidth,
      this.div.offsetHeight,
    );
    this.canvasCenter = new Point(
      this.canvasDimension.width / 2,
      this.canvasDimension.height / 2,
    );
    this.canvas.width = this.canvasDimension.width;
    this.canvas.height = this.canvasDimension.height;
    this.canvas.style.position = 'absolute';
    this.canvas.style.left = '0';
    this.canvas.style.top = '0';
    this.div.appendChild(this.canvas);
    this.ctx = this.canvas.getContext('2d') as CanvasRenderingContext2D;
    this.screenOffset = new Point(0, 0);
    this.virtualScreen = new PositionedRectangle(
      new Point(0, 0),
      new Rectangle(0, 0),
    );
    this.zoom = 1;

    // UML specific shapes
    this.triangle = [new Point(0, 0), new Point(-15, -10), new Point(-15, 10)];
    this.diamond = [
      new Point(0, 0),
      new Point(-10, -5),
      new Point(-20, 0),
      new Point(-10, 5),
    ];

    // Font
    // this.fontFamily = 'Roboto Mono'; // intentionally choose a monospaced font so it's easier for calculation (such as text wrapping)
    this.fontFamily = 'Arial'; // convert this back to non-monospaced font for now since monospaced fonts look rather off
    this.fontSize = 12;
    this.lineHeight = 14;

    // Wrap text
    this.truncateText = true;
    this.maxLineLength = 40;

    // Screen Grid (for debugging purpose)
    this.showScreenGrid = false;
    this.showScreenBoxGuide = true;
    this.screenGridAxisTickLength = 50;
    this.screenGridSpacingX = 100;
    this.screenGridSpacingY = 100;
    this.screenGridLineWidth = 0.5;

    // Canvas Grid
    this.showCanvasGrid = false;
    this.showCanvasBoxGuide = true;
    this.showScreenOffsetGuide = true;
    this.canvasGridAxisTickLength = 50;
    this.canvasGridSpacingX = 100;
    this.canvasGridSpacingY = 100;
    this.canvasGridLineWidth = 0.5;

    // Line
    this.defaultLineWidth = 1;

    // Color
    this.screenGridLineColor = 'rgba(61,126,154,0.56)';
    this.screenGridLabelTextColor = 'rgba(61,126,154,0.56)';
    this.screenGuideLineColor = 'red';
    this.screenGuideLabelTextColor = 'red';
    this.canvasGridLineColor = 'green';
    this.canvasGridLabelTextColor = 'green';
    this.canvasGuideLineColor = 'orange';
    this.canvasGuideLabelTextColor = 'orange';
    this.screenOffsetGuideLineColor = 'purple';
    this.screenOffsetGuideLabelTextColor = 'purple';
    this.defaultLineColor = 'rgb(0,0,0)';
    this.canvasColor = 'rgb(220,220,220)';
    this.backgroundColor = 'rgb(255,255,255)';
    this.classViewFillColor = 'rgb(185,185,185)';
    this.classViewHeaderTextColor = 'rgb(0,0,0)';
    this.classViewPropertyTextColor = 'rgb(0,0,0)';
    this.classViewPrimitivePropertyTextColor = 'rgb(255,255,255)';
    this.classViewDerivedPropertyTextColor = 'rgb(100,100,100)';
    this.relationshipViewTextColor = 'rgb(0,0,0)';
    this.propertyViewSharedDiamondColor = 'rgb(255,255,255)';
    this.propertyViewOwnedDiamondColor = 'rgb(0,0,0)';
    this.generalizationViewInheritanceTriangeFillColor = 'rgb(255,255,255)';
    this.selectionBoxBorderColor = 'rgba(0,0,0, 0.02)';

    // Preferences
    this.interactionMode = DIAGRAM_INTERACTION_MODE.LAYOUT;
    this.relationshipMode = DIAGRAM_RELATIONSHIP_EDIT_MODE.NONE;
    this.isReadOnly = false;
    this.enableLayoutAutoAdjustment = false;
    this.screenPadding = 20;
    this.classViewSpaceX = 10;
    this.classViewSpaceY = 4;
    this.propertySpacing = 10;

    // Event handlers
    this.selectionStart = undefined;
    this.selection = undefined;
    this.selectedClasses = [];
    this._selectedClassesInitialPositions = [];
    this.cursorPosition = new Point(0, 0);
    this.leftClick = false;
    this.middleClick = false;
    this.rightClick = false;
    this.clickX = 0;
    this.clickY = 0;
    this.positionBeforeLastMove = new Point(0, 0);
    this.div.onwheel = this.mousewheel.bind(this);
    this.div.onmousedown = this.mousedown.bind(this);
    this.div.onkeydown = this.keydown.bind(this);
    this.div.ondblclick = this.mousedblclick.bind(this);
    this.div.onmouseup = this.mouseup.bind(this);
    this.div.onmousemove = this.mousemove.bind(this);
  }

  setIsReadOnly(val: boolean): void {
    this.isReadOnly = val;
  }

  setEnableLayoutAutoAdjustment(val: boolean): void {
    this.enableLayoutAutoAdjustment = val;
  }

  setMouseOverClassView(val: ClassView | undefined): void {
    this.mouseOverClassView = val;
  }

  setMouseOverClassName(val: ClassView | undefined): void {
    this.mouseOverClassName = val;
  }

  setMouseOverClassCorner(val: ClassView | undefined): void {
    this.mouseOverClassCorner = val;
  }

  setMouseOverClassProperty(val: AbstractProperty | undefined): void {
    this.mouseOverClassProperty = val;
  }

  setMouseOverPropertyHolderViewLabel(
    val: PropertyHolderView | undefined,
  ): void {
    this.mouseOverPropertyHolderViewLabel = val;
  }

  setSelectionStart(val: Point | undefined): void {
    this.selectionStart = val;
  }

  setSelectedClassCorner(val: ClassView | undefined): void {
    this.selectedClassCorner = val;
  }

  setSelectedClasses(val: ClassView[]): void {
    this.selectedClasses = val;
  }

  setSelectedPropertyOrAssociation(val: PropertyHolderView | undefined): void {
    this.selectedPropertyOrAssociation = val;
  }

  setSelectedInheritance(val: GeneralizationView | undefined): void {
    this.selectedInheritance = val;
  }

  setLeftClick(val: boolean): void {
    this.leftClick = val;
  }

  setMiddleClick(val: boolean): void {
    this.middleClick = val;
  }

  setRightClick(val: boolean): void {
    this.rightClick = val;
  }

  setZoomLevel(val: number): void {
    this.zoom = val;
  }

  render(options?: { initial?: boolean | undefined }): void {
    this.diagram.classViews.forEach((classView) =>
      this.ensureClassViewMeetMinDimensions(classView),
    );
    this.refresh();

    if (options?.initial) {
      this.autoRecenter();

      // only zoom to fit if needed
      if (
        this.canvas.width <
          this.virtualScreen.rectangle.width +
            this.screenPadding * 2 +
            FIT_ZOOM_PADDING * 2 ||
        this.canvas.height <
          this.virtualScreen.rectangle.height +
            this.screenPadding * 2 +
            FIT_ZOOM_PADDING * 2
      ) {
        this.zoomToFit();
      }
    }
  }

  refresh(): void {
    this.refreshCanvas();
    this.drawScreen();
  }

  refreshCanvas(): void {
    this.canvasDimension = new Rectangle(
      this.div.offsetWidth,
      this.div.offsetHeight,
    );
    this.canvasCenter = new Point(
      this.canvasDimension.width / 2,
      this.canvasDimension.height / 2,
    );
    this.canvas.width = this.canvasDimension.width;
    this.canvas.height = this.canvasDimension.height;
  }

  clearScreen(): void {
    this.ctx.fillStyle = this.canvasColor;
    this.ctx.fillRect(
      0,
      0,
      this.canvasDimension.width,
      this.canvasDimension.height,
    );
  }

  private drawScreen(): void {
    this.manageVirtualScreen();
    this.clearScreen();
    this.drawAll();
  }

  autoRecenter(): void {
    this.center(
      this.virtualScreen.position.x + this.virtualScreen.rectangle.width / 2,
      this.virtualScreen.position.y + this.virtualScreen.rectangle.height / 2,
    );
  }

  /**
   * Reset the screen offset
   */
  private center(x: number, y: number): void {
    this.screenOffset = new Point(
      -x + this.canvasCenter.x,
      -y + this.canvasCenter.y,
    );
    this.refresh();
  }

  changeMode(
    editMode: DIAGRAM_INTERACTION_MODE,
    relationshipMode: DIAGRAM_RELATIONSHIP_EDIT_MODE,
  ): void {
    switch (editMode) {
      case DIAGRAM_INTERACTION_MODE.LAYOUT:
      case DIAGRAM_INTERACTION_MODE.PAN:
      case DIAGRAM_INTERACTION_MODE.ZOOM_IN:
      case DIAGRAM_INTERACTION_MODE.ZOOM_OUT:
      case DIAGRAM_INTERACTION_MODE.ADD_CLASS: {
        if (relationshipMode !== DIAGRAM_RELATIONSHIP_EDIT_MODE.NONE) {
          throw new IllegalStateError(
            `Can't change to '${editMode}' mode: relationship mode should not be specified in layout mode`,
          );
        }
        break;
      }
      case DIAGRAM_INTERACTION_MODE.ADD_RELATIONSHIP: {
        if (relationshipMode === DIAGRAM_RELATIONSHIP_EDIT_MODE.NONE) {
          throw new IllegalStateError(
            `Can't switch to relationship mode: relationship mode is not specified`,
          );
        }
        break;
      }
      default:
        throw new UnsupportedOperationError(
          `Can't switch to mode '${editMode}': unsupported mode`,
        );
    }

    this.interactionMode = editMode;
    this.relationshipMode = relationshipMode;

    if (editMode === DIAGRAM_INTERACTION_MODE.ADD_RELATIONSHIP) {
      switch (relationshipMode) {
        case DIAGRAM_RELATIONSHIP_EDIT_MODE.INHERITANCE: {
          this.handleAddRelationship = (
            startClassView: ClassView,
            targetClassView: ClassView,
          ): RelationshipView | undefined => {
            if (
              // Do not allow creating self-inheritance
              startClassView.class.value !== targetClassView.class.value &&
              // Avoid creating inhertance that already existed
              !getAllSuperclasses(startClassView.class.value).includes(
                targetClassView.class.value,
              ) &&
              // Avoid loop (might be expensive)
              !getAllSuperclasses(targetClassView.class.value).includes(
                startClassView.class.value,
              )
            ) {
              class_addSuperType(
                startClassView.class.value,
                GenericTypeExplicitReference.create(
                  new GenericType(targetClassView.class.value),
                ),
              );
            }
            // only add an inheritance relationship view if the start class
            // has already had the target class as its supertype
            if (
              startClassView.class.value.generalizations.find(
                (generalization) =>
                  generalization.value.rawType === targetClassView.class.value,
              )
            ) {
              const gview = new GeneralizationView(
                this.diagram,
                startClassView,
                targetClassView,
              );
              diagram_addGeneralizationView(this.diagram, gview);
              return gview;
            }
            return undefined;
          };
          break;
        }
        case DIAGRAM_RELATIONSHIP_EDIT_MODE.PROPERTY: {
          this.handleAddRelationship = (
            startClassView: ClassView,
            targetClassView: ClassView,
          ): PropertyView | undefined => {
            const property = new Property(
              `property_${startClassView.class.value.properties.length + 1}`,
              Multiplicity.ONE,
              GenericTypeExplicitReference.create(
                new GenericType(targetClassView.class.value),
              ),
              startClassView.class.value,
            );
            class_addProperty(startClassView.class.value, property);
            // only create property view if the classviews are different
            // else we end up with a weird rendering where the property view
            // is not targetable
            if (startClassView !== targetClassView) {
              const pView = new PropertyView(
                this.diagram,
                PropertyExplicitReference.create(property),
                startClassView,
                targetClassView,
              );
              diagram_addPropertyView(this.diagram, pView);
              return pView;
            }
            return undefined;
          };
          break;
        }
        default:
          throw new UnsupportedOperationError(
            `Can't switch to relationship mode '${relationshipMode}': unsupported mode`,
          );
      }
    }
  }

  align(op: DIAGRAM_ALIGNER_OPERATOR): void {
    if (this.selectedClasses.length < 2) {
      return;
    }
    switch (op) {
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_LEFT: {
        const leftBound = this.selectedClasses.reduce(
          (val, view) => Math.min(val, view.position.x),
          Number.MAX_SAFE_INTEGER,
        );
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(leftBound, view.position.y),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_CENTER: {
        const center =
          this.selectedClasses.reduce(
            (val, view) => val + view.position.x + view.rectangle.width / 2,
            0,
          ) / this.selectedClasses.length;
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(center - view.rectangle.width / 2, view.position.y),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_RIGHT: {
        const rightBound = this.selectedClasses.reduce(
          (val, view) => Math.max(val, view.position.x + view.rectangle.width),
          -Number.MAX_SAFE_INTEGER,
        );
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(rightBound - view.rectangle.width, view.position.y),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_TOP: {
        const topBound = this.selectedClasses.reduce(
          (val, view) => Math.min(val, view.position.y),
          Number.MAX_SAFE_INTEGER,
        );
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(view.position.x, topBound),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_MIDDLE: {
        const middle =
          this.selectedClasses.reduce(
            (val, view) => val + view.position.y + view.rectangle.height / 2,
            0,
          ) / this.selectedClasses.length;
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(view.position.x, middle - view.rectangle.height / 2),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.ALIGN_BOTTOM: {
        const bottomBound = this.selectedClasses.reduce(
          (val, view) => Math.max(val, view.position.y + view.rectangle.height),
          -Number.MAX_SAFE_INTEGER,
        );
        this.selectedClasses.forEach((view) =>
          positionedRectangle_setPosition(
            view,
            new Point(view.position.x, bottomBound - view.rectangle.height),
          ),
        );
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.SPACE_HORIZONTALLY: {
        const sorted = this.selectedClasses.toSorted(
          (a, b) => a.position.x - b.position.x,
        );
        // NOTE: handle special case where there are only 2 views, make them adjacent
        if (sorted.length === 2) {
          const previousView = sorted[0] as ClassView;
          const currentView = sorted[1] as ClassView;
          positionedRectangle_setPosition(
            currentView,
            new Point(
              previousView.position.x + previousView.rectangle.width,
              currentView.position.y,
            ),
          );
        } else {
          const spacings = [];
          for (let idx = 1; idx < sorted.length; idx++) {
            const previousView = sorted[idx - 1] as ClassView;
            const currentView = sorted[idx] as ClassView;
            spacings.push(
              currentView.position.x -
                (previousView.position.x + previousView.rectangle.width),
            );
          }
          const averageSpacing =
            spacings.reduce((val, distance) => val + distance, 0) /
            spacings.length;
          for (let idx = 1; idx < sorted.length; idx++) {
            const previousView = sorted[idx - 1] as ClassView;
            const currentView = sorted[idx] as ClassView;
            positionedRectangle_setPosition(
              currentView,
              new Point(
                previousView.position.x +
                  previousView.rectangle.width +
                  averageSpacing,
                currentView.position.y,
              ),
            );
          }
        }
        break;
      }
      case DIAGRAM_ALIGNER_OPERATOR.SPACE_VERTICALLY: {
        const sorted = this.selectedClasses.toSorted(
          (a, b) => a.position.y - b.position.y,
        );
        // NOTE: handle special case where there are only 2 views, make them adjacent
        if (sorted.length === 2) {
          const previousView = sorted[0] as ClassView;
          const currentView = sorted[1] as ClassView;
          positionedRectangle_setPosition(
            currentView,
            new Point(
              currentView.position.x,
              previousView.position.y + previousView.rectangle.height,
            ),
          );
        } else {
          const spacings = [];
          for (let idx = 1; idx < sorted.length; idx++) {
            const previousView = sorted[idx - 1] as ClassView;
            const currentView = sorted[idx] as ClassView;
            spacings.push(
              currentView.position.y -
                (previousView.position.y + previousView.rectangle.height),
            );
          }
          const averageSpacing =
            spacings.reduce((val, distance) => val + distance, 0) /
            spacings.length;
          for (let idx = 1; idx < sorted.length; idx++) {
            const previousView = sorted[idx - 1] as ClassView;
            const currentView = sorted[idx] as ClassView;
            positionedRectangle_setPosition(
              currentView,
              new Point(
                currentView.position.x,
                previousView.position.y +
                  previousView.rectangle.height +
                  averageSpacing,
              ),
            );
          }
        }
        break;
      }
      default:
        break;
    }

    this.drawScreen();
  }

  truncateTextWithEllipsis(val: string, limit = this.maxLineLength): string {
    const ellipsis = '...';
    return val.length > limit
      ? `${val.substring(0, limit + 1 - ellipsis.length)}${ellipsis}`
      : val;
  }

  canvasCoordinateToModelCoordinate(point: Point): Point {
    return new Point(
      (point.x - this.canvasCenter.x) / this.zoom -
        this.screenOffset.x +
        this.canvasCenter.x,
      (point.y - this.canvasCenter.y) / this.zoom -
        this.screenOffset.y +
        this.canvasCenter.y,
    );
  }

  modelCoordinateToCanvasCoordinate(point: Point): Point {
    return new Point(
      (point.x - this.canvasCenter.x + this.screenOffset.x) * this.zoom +
        this.canvasCenter.x,
      (point.y - this.canvasCenter.y + this.screenOffset.y) * this.zoom +
        this.canvasCenter.y,
    );
  }

  /**
   * Mouse events' coordinate x,y are relative to the viewport, not the canvas element
   * so we need to calculate them relative to the canvas element
   */
  resolveMouseEventCoordinate(e: MouseEvent): Point {
    if (e.target instanceof HTMLElement) {
      const targetEl = getElementPosition(e.target);
      return new Point(targetEl.x + e.offsetX, targetEl.y + e.offsetY);
    }
    // NOTE: this is a fallback, should not happen
    // since all mouse events shoud target the canvas element
    return new Point(e.x, e.y);
  }

  eventCoordinateToCanvasCoordinate(point: Point): Point {
    return new Point(
      point.x - this.divPosition.x + this.div.scrollLeft,
      point.y - this.divPosition.y + this.div.scrollTop,
    );
  }

  canvasCoordinateToEventCoordinate(point: Point): Point {
    return new Point(
      point.x - this.div.scrollLeft + this.divPosition.x,
      point.y - this.div.scrollTop + this.divPosition.y,
    );
  }

  hasPropertyView(classView: ClassView, property: AbstractProperty): boolean {
    return (
      this.diagram.propertyViews.filter(
        (p) =>
          p.property.value === property && p.from.classView.value === classView,
      ).length > 0
    );
  }

  get divPosition(): Point {
    return getElementPosition(this.div);
  }

  private manageVirtualScreen(): void {
    if (this.diagram.classViews.length) {
      const firstClassView = guaranteeNonNullable(this.diagram.classViews[0]);
      let minX = firstClassView.position.x;
      let minY = firstClassView.position.y;
      let maxX = firstClassView.position.x + firstClassView.rectangle.width;
      let maxY = firstClassView.position.y + firstClassView.rectangle.height;
      for (const classView of this.diagram.classViews) {
        minX = Math.min(minX, classView.position.x);
        minY = Math.min(minY, classView.position.y);
        maxX = Math.max(maxX, classView.position.x + classView.rectangle.width);
        maxY = Math.max(
          maxY,
          classView.position.y + classView.rectangle.height,
        );
      }
      const relationshipViews = (
        this.diagram.associationViews as RelationshipView[]
      )
        .concat(this.diagram.generalizationViews)
        .concat(this.diagram.propertyViews);
      for (const relationshipView of relationshipViews) {
        const fullPath = RelationshipView.pruneUnnecessaryInsidePoints(
          relationshipView.buildFullPath(),
          relationshipView.from.classView.value,
          relationshipView.to.classView.value,
        );
        if (relationshipView instanceof PropertyView) {
          const box = this.drawLinePropertyText(
            // NOTE: by the way we compute the full path, it would guarantee
            // to always have at least 2 points
            guaranteeNonNullable(
              fullPath[fullPath.length - 2],
              'Diagram path expected to have at least 2 points',
            ),
            guaranteeNonNullable(
              fullPath[fullPath.length - 1],
              'Diagram path expected to have at least 2 points',
            ),
            relationshipView.to.classView.value,
            relationshipView.property.value,
            false,
          );
          minX = Math.min(minX, box.position.x);
          minY = Math.min(minY, box.position.y);
          maxX = Math.max(maxX, getBottomRightCornerPoint(box).x);
          maxY = Math.max(maxY, getBottomRightCornerPoint(box).y);
        }
        // if (relationshipView.from.name) {
        //   var box = this.displayText(fullPath[1], fullPath[0], relationshipView.from.classView, relationshipView.property, this.ctx);
        //   minX = Math.min(minX, box.x);
        //   minY = Math.min(minY, box.y);
        //   maxX = Math.max(maxX, box.x2);
        //   maxY = Math.max(maxY, box.y2);
        // }
        for (const point of relationshipView.path) {
          minX = Math.min(minX, point.x);
          minY = Math.min(minY, point.y);
          maxX = Math.max(maxX, point.x);
          maxY = Math.max(maxY, point.y);
        }
      }
      this.virtualScreen = new PositionedRectangle(
        new Point(minX, minY),
        new Rectangle(maxX - minX, maxY - minY),
      );
    } else {
      this.setZoomLevel(1);
      this.screenOffset = new Point(0, 0);
      this.virtualScreen = new PositionedRectangle(
        new Point(
          this.canvasDimension.width / 2,
          this.canvasDimension.height / 2,
        ),
        new Rectangle(0, 0),
      );
    }
  }

  /**
   * Here we zoom with respect to the point the mouse is currently pointing at.
   * The idea is fairly simple. We convert the coordinate of the zoom point
   * to the model coordinate and find a way to alter `screenOffset` in response
   * to change in zoom level to ensure the model coordinate stays constant.
   */
  private executeZoom(newZoomLevel: number, point: Point): void {
    // NOTE: we cap the minimum zoom level to avoid negative zoom
    newZoomLevel = Math.max(newZoomLevel, MIN_ZOOM_LEVEL);

    const currentZoomLevel = this.zoom;
    this.setZoomLevel(newZoomLevel);

    this.screenOffset = new Point(
      ((point.x - this.canvasCenter.x) * (currentZoomLevel - newZoomLevel) +
        this.screenOffset.x * currentZoomLevel) /
        newZoomLevel,
      ((point.y - this.canvasCenter.y) * (currentZoomLevel - newZoomLevel) +
        this.screenOffset.y * currentZoomLevel) /
        newZoomLevel,
    );

    this.clearScreen();
    this.drawAll();
  }

  private zoomPoint(zoomLevel: number, zoomPoint: Point): void {
    this.executeZoom(zoomLevel, zoomPoint);
  }

  zoomCenter(zoomLevel: number): void {
    // NOTE: we cap the minimum zoom level to avoid negative zoom
    this.setZoomLevel(Math.max(zoomLevel, MIN_ZOOM_LEVEL));
    this.clearScreen();
    this.drawAll();
  }

  zoomToFit(): void {
    this.autoRecenter();
    this.zoomCenter(
      Math.max(
        Math.min(
          this.canvas.width /
            (this.virtualScreen.rectangle.width +
              this.screenPadding * 2 +
              FIT_ZOOM_PADDING * 2),
          this.canvas.height /
            (this.virtualScreen.rectangle.height +
              this.screenPadding * 2 +
              FIT_ZOOM_PADDING * 2),
        ),
        MIN_ZOOM_LEVEL,
      ),
    );
  }

  /**
   * Add a classview to current diagram and draw it.
   * This function is intended to be used with drag and drop, hence the position paramter, which must be relative to the screen/window
   */
  addClassView(
    addedClass: Class,
    classViewModelCoordinate?: Point,
  ): ClassView | undefined {
    if (!this.isReadOnly) {
      // NOTE: Using `uuid` might be overkill since the `id` is only required to be unique
      // across the diagram, but maintaining a counter has its own downside
      // NOTE: checking for collision to guarantee stability, especially since class view is usually manually added
      const existingIds = this.diagram.classViews.map(
        (classView) => classView.id,
      );
      let id = uuid();
      while (existingIds.includes(id)) {
        id = uuid();
      }
      const newClassView = new ClassView(
        this.diagram,
        id,
        PackageableElementExplicitReference.create(addedClass),
      );
      positionedRectangle_setPosition(
        newClassView,
        classViewModelCoordinate ??
          this.canvasCoordinateToModelCoordinate(
            new Point(
              this.virtualScreen.position.x +
                this.virtualScreen.rectangle.width / 2,
              this.virtualScreen.position.y +
                this.virtualScreen.rectangle.height / 2,
            ),
          ),
      );
      diagram_addClassView(this.diagram, newClassView);
      // Refresh hash since ClassView position is not observable
      // NOTE: here we refresh after adding the class view to the diagram, that way the diagram hash is refreshed
      positionedRectangle_forceRefreshHash(newClassView);
      this.diagram.classViews
        .filter((classView) => classView.class.value !== addedClass)
        .forEach((classView) => {
          const _class = classView.class.value;
          // Add supertype
          if (
            addedClass.generalizations
              .map((generalization) => generalization.value.rawType)
              .includes(_class)
          ) {
            diagram_addGeneralizationView(
              this.diagram,
              new GeneralizationView(this.diagram, newClassView, classView),
            );
          }
          if (
            _class.generalizations
              .map((generalization) => generalization.value.rawType)
              .includes(addedClass)
          ) {
            diagram_addGeneralizationView(
              this.diagram,

              new GeneralizationView(this.diagram, classView, newClassView),
            );
          }
          // Add property view
          getAllOwnClassProperties(addedClass).forEach((property) => {
            if (property.genericType.value.rawType === _class) {
              diagram_addPropertyView(
                this.diagram,

                new PropertyView(
                  this.diagram,
                  PropertyExplicitReference.create(property),
                  newClassView,
                  classView,
                ),
              );
            }
          });
          getAllOwnClassProperties(_class).forEach((property) => {
            if (property.genericType.value.rawType === addedClass) {
              diagram_addPropertyView(
                this.diagram,
                new PropertyView(
                  this.diagram,
                  PropertyExplicitReference.create(property),
                  classView,
                  newClassView,
                ),
              );
            }
          });
        });
      this.drawClassView(newClassView);
      this.drawScreen();
      return newClassView;
    }
    return undefined;
  }

  private drawBoundingBox(): void {
    this.ctx.fillStyle = this.backgroundColor;
    this.ctx.lineWidth = 1;
    this.ctx.fillRect(
      (this.virtualScreen.position.x +
        this.screenOffset.x -
        this.canvasCenter.x -
        this.screenPadding) *
        this.zoom +
        this.canvasCenter.x,
      (this.virtualScreen.position.y +
        this.screenOffset.y -
        this.canvasCenter.y -
        this.screenPadding) *
        this.zoom +
        this.canvasCenter.y,
      (this.virtualScreen.rectangle.width + this.screenPadding * 2) * this.zoom,
      (this.virtualScreen.rectangle.height + this.screenPadding * 2) *
        this.zoom,
    );
    this.ctx.strokeRect(
      (this.virtualScreen.position.x +
        this.screenOffset.x -
        this.canvasCenter.x -
        this.screenPadding) *
        this.zoom +
        this.canvasCenter.x,
      (this.virtualScreen.position.y +
        this.screenOffset.y -
        this.canvasCenter.y -
        this.screenPadding) *
        this.zoom +
        this.canvasCenter.y,
      (this.virtualScreen.rectangle.width + this.screenPadding * 2) * this.zoom,
      (this.virtualScreen.rectangle.height + this.screenPadding * 2) *
        this.zoom,
    );
  }

  private drawDiagram(): void {
    this.diagram.associationViews.forEach((associationView) =>
      this.drawPropertyOrAssociation(associationView),
    );
    this.diagram.generalizationViews.forEach((generalizationView) =>
      this.drawInheritance(generalizationView),
    );
    this.diagram.propertyViews.forEach((propertyView) =>
      this.drawPropertyOrAssociation(propertyView),
    );
    this.diagram.classViews.forEach((classView) =>
      this.drawClassView(classView),
    );
    if (this.showCanvasGrid) {
      this.drawCanvasGrid();
    }
    if (this.showScreenGrid) {
      this.drawScreenGrid();
    }
  }

  drawAll(): void {
    this.drawBoundingBox();
    this.drawDiagram();
  }

  private drawScreenGrid(): void {
    const startX =
      (this.virtualScreen.position.x +
        this.screenOffset.x -
        this.canvasCenter.x) *
        this.zoom +
      this.canvasCenter.x;
    const startY =
      (this.virtualScreen.position.y +
        this.screenOffset.y -
        this.canvasCenter.y) *
        this.zoom +
      this.canvasCenter.y;
    const width =
      (this.virtualScreen.rectangle.width + this.screenPadding * 2) * this.zoom;
    const height =
      (this.virtualScreen.rectangle.height + this.screenPadding * 2) *
      this.zoom;
    this.ctx.beginPath();
    this.ctx.fillStyle = this.screenGridLabelTextColor;
    this.ctx.strokeStyle = this.screenGridLineColor;
    this.ctx.lineWidth = this.screenGridLineWidth;
    this.ctx.font = `${(this.fontSize - 1) * this.zoom}px ${this.fontFamily}`;
    const labelPadding = 5;
    // draw vertical grid lines
    let gridX = 0;
    for (
      let x = startX;
      x < startX + width - this.screenPadding * 2;
      x += this.screenGridSpacingX * this.zoom
    ) {
      this.ctx.fillText(
        `${gridX}`,
        x + labelPadding * this.zoom,
        startY -
          (this.screenGridAxisTickLength + this.screenPadding) * this.zoom,
      );
      this.ctx.fillText(
        `[${Math.round(this.virtualScreen.position.x + gridX)}]`,
        x + labelPadding * this.zoom,
        startY -
          (this.screenGridAxisTickLength +
            this.screenPadding -
            this.lineHeight) *
            this.zoom,
      );
      this.ctx.moveTo(
        x,
        startY -
          (this.screenGridAxisTickLength + this.screenPadding) * this.zoom,
      );
      this.ctx.lineTo(x, startY + height - this.screenPadding * this.zoom);
      this.ctx.stroke();
      gridX += this.screenGridSpacingX;
    }
    // draw horizontal grid lines
    let gridY = 0;
    for (
      let y = startY;
      y < startY + height - this.screenPadding * 2;
      y += this.screenGridSpacingY * this.zoom
    ) {
      this.ctx.fillText(
        `${gridY}`,
        startX -
          (this.screenGridAxisTickLength + this.screenPadding) * this.zoom,
        y + labelPadding * this.zoom,
      );
      this.ctx.fillText(
        `[${Math.round(this.virtualScreen.position.y + gridY)}]`,
        startX -
          (this.screenGridAxisTickLength + this.screenPadding) * this.zoom,
        y + (labelPadding + this.lineHeight) * this.zoom,
      );
      this.ctx.moveTo(
        startX -
          (this.screenGridAxisTickLength + this.screenPadding) * this.zoom,
        y,
      );
      this.ctx.lineTo(startX + width - this.screenPadding * this.zoom, y);
      this.ctx.stroke();
      gridY += this.screenGridSpacingY;
    }
    // draw screen padding border grid line
    if (this.showScreenBoxGuide) {
      this.ctx.beginPath();
      this.ctx.fillStyle = this.screenGuideLabelTextColor;
      this.ctx.strokeStyle = this.screenGuideLineColor;
      this.ctx.moveTo(startX, startY);
      this.ctx.lineTo(
        startX,
        startY + height - this.screenPadding * 2 * this.zoom,
      );
      this.ctx.stroke();
      this.ctx.lineTo(
        startX,
        startY + height - this.screenPadding * 2 * this.zoom,
      );
      this.ctx.lineTo(
        startX + width - this.screenPadding * 2 * this.zoom,
        startY + height - this.screenPadding * 2 * this.zoom,
      );
      this.ctx.stroke();
      this.ctx.lineTo(
        startX + width - this.screenPadding * 2 * this.zoom,
        startY + height - this.screenPadding * 2 * this.zoom,
      );
      this.ctx.lineTo(
        startX + width - this.screenPadding * 2 * this.zoom,
        startY,
      );
      this.ctx.stroke();
      this.ctx.lineTo(
        startX + width - this.screenPadding * 2 * this.zoom,
        startY,
      );
      this.ctx.lineTo(startX, startY);
      this.ctx.stroke();
      // draw center guides
      this.ctx.fillText(
        `${Math.round(this.virtualScreen.rectangle.width / 2)}`,
        startX + width / 2 - (this.screenPadding - labelPadding) * this.zoom,
        startY + labelPadding * this.zoom,
      );
      this.ctx.fillText(
        `[${Math.round(
          this.virtualScreen.position.x +
            this.virtualScreen.rectangle.width / 2,
        )}]`,
        startX + width / 2 - (this.screenPadding - labelPadding) * this.zoom,
        startY + (labelPadding + this.lineHeight) * this.zoom,
      );
      this.ctx.lineTo(
        startX + width / 2 - this.screenPadding * this.zoom,
        startY,
      );
      this.ctx.lineTo(
        startX + width / 2 - this.screenPadding * this.zoom,
        startY + height - this.screenPadding * 2 * this.zoom,
      );
      this.ctx.stroke();
      this.ctx.fillText(
        `${Math.round(this.virtualScreen.rectangle.height / 2)}`,
        startX + labelPadding * this.zoom,
        startY + height / 2 - (this.screenPadding - labelPadding) * this.zoom,
      );
      this.ctx.fillText(
        `[${Math.round(
          this.virtualScreen.position.y +
            this.virtualScreen.rectangle.height / 2,
        )}]`,
        startX + labelPadding * this.zoom,
        startY +
          height / 2 -
          (this.screenPadding - labelPadding - this.lineHeight) * this.zoom,
      );
      this.ctx.lineTo(
        startX,
        startY + height / 2 - this.screenPadding * this.zoom,
      );
      this.ctx.lineTo(
        startX + width - this.screenPadding * 2 * this.zoom,
        startY + height / 2 - this.screenPadding * this.zoom,
      );
      this.ctx.stroke();
    }
    this.ctx.strokeStyle = this.defaultLineColor;
    this.ctx.lineWidth = this.defaultLineWidth;
  }

  private drawCanvasGrid(): void {
    const startX = -this.canvasCenter.x * this.zoom + this.canvasCenter.x;
    const startY = -this.canvasCenter.y * this.zoom + this.canvasCenter.y;
    const width = this.canvasDimension.width;
    const height = this.canvasDimension.height;
    this.ctx.setLineDash([5, 5]);
    this.ctx.fillStyle = this.canvasGridLabelTextColor;
    this.ctx.strokeStyle = this.canvasGridLineColor;
    this.ctx.lineWidth = this.canvasGridLineWidth;
    this.ctx.font = `${(this.fontSize - 1) * this.zoom}px ${this.fontFamily}`;
    const labelPadding = 5;
    this.ctx.beginPath();
    // draw vertical grid lines
    let gridX = 0;
    for (let x = startX; x < width; x += this.canvasGridSpacingX * this.zoom) {
      if (x !== 0) {
        this.ctx.fillText(
          `[${Math.round(gridX)}]`,
          x + labelPadding * this.zoom,
          labelPadding * this.zoom,
        );
      }
      this.ctx.moveTo(x, 0);
      this.ctx.lineTo(x, height);
      this.ctx.stroke();
      gridX += this.canvasGridSpacingX;
    }
    // draw horizontal grid lines
    let gridY = 0;
    for (let y = startY; y < height; y += this.canvasGridSpacingY * this.zoom) {
      if (y !== 0) {
        this.ctx.fillText(
          `[${Math.round(gridY)}]`,
          labelPadding * this.zoom,
          y