polyControl.ts

import { Point } from '../point.class';
import { Control } from './control.class';
import { TMat2D } from '../typedefs';
import { iMatrix } from '../constants';
import type { Polyline } from '../shapes/polyline.class';
import { multiplyTransformMatrices } from '../util/misc/matrix';
import {
  TPointerEvent,
  Transform,
  TransformActionHandler,
} from '../EventTypeDefs';
import { getLocalPoint } from './util';

type TTransformAnchor = Transform & { pointIndex: number };

const getSize = (poly: Polyline) => {
  return new Point(poly.width, poly.height);
};

/**
 * This function locates the controls.
 * It'll be used both for drawing and for interaction.
 */
const factoryPolyPositionHandler = (pointIndex: number) => {
  return function (dim: Point, finalMatrix: TMat2D, polyObject: Polyline) {
    const x = polyObject.points[pointIndex].x - polyObject.pathOffset.x,
      y = polyObject.points[pointIndex].y - polyObject.pathOffset.y;
    return new Point(x, y).transform(
      multiplyTransformMatrices(
        polyObject.canvas?.viewportTransform ?? iMatrix,
        polyObject.calcTransformMatrix()
      )
    );
  };
};

/**
 * This function defines what the control does.
 * It'll be called on every mouse move after a control has been clicked and is being dragged.
 * The function receives as argument the mouse event, the current transform object
 * and the current position in canvas coordinate `transform.target` is a reference to the
 * current object being transformed.
 */
const polyActionHandler = (
  eventData: TPointerEvent,
  transform: TTransformAnchor,
  x: number,
  y: number
) => {
  const poly = transform.target as Polyline,
    pointIndex = transform.pointIndex,
    mouseLocalPosition = getLocalPoint(transform, 'center', 'center', x, y),
    polygonBaseSize = getSize(poly),
    size = poly._getTransformedDimensions(),
    sizeFactor = polygonBaseSize.divide(size),
    adjustFlip = new Point(poly.flipX ? -1 : 1, poly.flipY ? -1 : 1);

  const finalPointPosition = mouseLocalPosition
    .multiply(adjustFlip)
    .multiply(sizeFactor)
    .add(poly.pathOffset);

  poly.points[pointIndex] = finalPointPosition;
  poly.setDimensions();

  return true;
};

/**
 * Keep the polygon in the same position when we change its `width`/`height`/`top`/`left`.
 */
const anchorWrapper = (
  pointIndex: number,
  fn: TransformActionHandler<TTransformAnchor>
) => {
  return function (
    eventData: TPointerEvent,
    transform: Transform,
    x: number,
    y: number
  ) {
    const poly = transform.target as Polyline,
      anchorIndex = (pointIndex > 0 ? pointIndex : poly.points.length) - 1,
      pointInParentPlane = new Point(
        poly.points[anchorIndex].x - poly.pathOffset.x,
        poly.points[anchorIndex].y - poly.pathOffset.y
      ).transform(poly.calcOwnMatrix()),
      actionPerformed = fn(eventData, { ...transform, pointIndex }, x, y),
      polygonBaseSize = getSize(poly),
      adjustFlip = new Point(poly.flipX ? -1 : 1, poly.flipY ? -1 : 1);

    const newPosition = new Point(
      poly.points[anchorIndex].x,
      poly.points[anchorIndex].y
    )
      .subtract(poly.pathOffset)
      .divide(polygonBaseSize)
      .multiply(adjustFlip);

    poly.setPositionByOrigin(
      pointInParentPlane,
      newPosition.x + 0.5,
      newPosition.y + 0.5
    );
    return actionPerformed;
  };
};

export function createPolyControls(
  poly: Polyline,
  options?: Partial<Control>
): Record<string, Control>;
export function createPolyControls(
  numOfControls: number,
  options?: Partial<Control>
): Record<string, Control>;
export function createPolyControls(
  arg0: number | Polyline,
  options: Partial<Control> = {}
) {
  const controls = {} as Record<string, Control>;
  for (
    let idx = 0;
    idx < (typeof arg0 === 'number' ? arg0 : arg0.points.length);
    idx++
  ) {
    controls[`p${idx}`] = new Control({
      actionName: 'modifyPoly',
      positionHandler: factoryPolyPositionHandler(idx),
      actionHandler: anchorWrapper(idx, polyActionHandler),
      ...options,
    });
  }
  return controls;
}