xyflow/packages/system/src/xyresizer/XYResizer.ts

import { drag } from 'd3-drag';
import { select } from 'd3-selection';

import { getControlDirection, getDimensionsAfterResize, getResizeDirection } from './utils';
import { getPointerPosition } from '../utils';
import type {
  CoordinateExtent,
  InternalNodeBase,
  NodeBase,
  NodeLookup,
  NodeOrigin,
  Transform,
  XYPosition,
} from '../types';
import type { OnResize, OnResizeEnd, OnResizeStart, ResizeDragEvent, ShouldResize, ControlPosition } from './types';

const initPrevValues = { width: 0, height: 0, x: 0, y: 0 };

const initStartValues = {
  ...initPrevValues,
  pointerX: 0,
  pointerY: 0,
  aspectRatio: 1,
};

export type XYResizerChange = {
  x?: number;
  y?: number;
  width?: number;
  height?: number;
};

export type XYResizerChildChange = {
  id: string;
  position: XYPosition;
  extent?: 'parent' | CoordinateExtent;
};

type XYResizerParams = {
  domNode: HTMLDivElement;
  nodeId: string;
  getStoreItems: () => {
    nodeLookup: NodeLookup;
    transform: Transform;
    snapGrid?: [number, number];
    snapToGrid: boolean;
    nodeOrigin: NodeOrigin;
  };
  onChange: (changes: XYResizerChange, childChanges: XYResizerChildChange[]) => void;
  onEnd?: () => void;
};

type XYResizerUpdateParams = {
  controlPosition: ControlPosition;
  boundaries: {
    minWidth: number;
    minHeight: number;
    maxWidth: number;
    maxHeight: number;
  };
  keepAspectRatio: boolean;
  onResizeStart: OnResizeStart | undefined;
  onResize: OnResize | undefined;
  onResizeEnd: OnResizeEnd | undefined;
  shouldResize: ShouldResize | undefined;
};

export type XYResizerInstance = {
  update: (params: XYResizerUpdateParams) => void;
  destroy: () => void;
};

function nodeToParentExtent(node: NodeBase): CoordinateExtent {
  return [
    [0, 0],
    [node.measured!.width!, node.measured!.height!],
  ];
}

function nodeToChildExtent(child: NodeBase, parent: NodeBase, nodeOrigin: NodeOrigin): CoordinateExtent {
  const x = parent.position.x + child.position.x;
  const y = parent.position.y + child.position.y;
  const width = child.measured!.width! ?? 0;
  const height = child.measured!.height! ?? 0;
  const originOffsetX = nodeOrigin[0] * width;
  const originOffsetY = nodeOrigin[1] * height;

  return [
    [x - originOffsetX, y - originOffsetY],
    [x + width - originOffsetX, y + height - originOffsetY],
  ];
}

export function XYResizer({ domNode, nodeId, getStoreItems, onChange, onEnd }: XYResizerParams): XYResizerInstance {
  const selection = select(domNode);

  function update({
    controlPosition,
    boundaries,
    keepAspectRatio,
    onResizeStart,
    onResize,
    onResizeEnd,
    shouldResize,
  }: XYResizerUpdateParams) {
    let prevValues = { ...initPrevValues };
    let startValues = { ...initStartValues };

    const controlDirection = getControlDirection(controlPosition);

    let node: InternalNodeBase | undefined = undefined;
    let childNodes: XYResizerChildChange[] = [];
    let parentNode: InternalNodeBase | undefined = undefined; // Needed to fix expandParent
    let parentExtent: CoordinateExtent | undefined = undefined;
    let childExtent: CoordinateExtent | undefined = undefined;

    const dragHandler = drag<HTMLDivElement, unknown>()
      .on('start', (event: ResizeDragEvent) => {
        const { nodeLookup, transform, snapGrid, snapToGrid, nodeOrigin } = getStoreItems();
        node = nodeLookup.get(nodeId);

        if (!node) {
          return;
        }

        const { xSnapped, ySnapped } = getPointerPosition(event.sourceEvent, { transform, snapGrid, snapToGrid });

        prevValues = {
          width: node.measured.width ?? 0,
          height: node.measured.height ?? 0,
          x: node.position.x ?? 0,
          y: node.position.y ?? 0,
        };

        startValues = {
          ...prevValues,
          pointerX: xSnapped,
          pointerY: ySnapped,
          aspectRatio: prevValues.width / prevValues.height,
        };

        parentNode = undefined;

        if (node.parentId && (node.extent === 'parent' || node.expandParent)) {
          parentNode = nodeLookup.get(node.parentId);
          parentExtent = parentNode && node.extent === 'parent' ? nodeToParentExtent(parentNode) : undefined;
        }

        // Collect all child nodes to correct their relative positions when top/left changes
        // Determine largest minimal extent the parent node is allowed to resize to
        childNodes = [];
        childExtent = undefined;

        for (const [childId, child] of nodeLookup) {
          if (child.parentId === nodeId) {
            childNodes.push({
              id: childId,
              position: { ...child.position },
              extent: child.extent,
            });

            if (child.extent === 'parent' || child.expandParent) {
              const extent = nodeToChildExtent(child, node, child.origin ?? nodeOrigin);

              if (childExtent) {
                childExtent = [
                  [Math.min(extent[0][0], childExtent[0][0]), Math.min(extent[0][1], childExtent[0][1])],
                  [Math.max(extent[1][0], childExtent[1][0]), Math.max(extent[1][1], childExtent[1][1])],
                ];
              } else {
                childExtent = extent;
              }
            }
          }
        }

        onResizeStart?.(event, { ...prevValues });
      })
      .on('drag', (event: ResizeDragEvent) => {
        const { transform, snapGrid, snapToGrid, nodeOrigin: storeNodeOrigin } = getStoreItems();
        const pointerPosition = getPointerPosition(event.sourceEvent, { transform, snapGrid, snapToGrid });
        const childChanges: XYResizerChildChange[] = [];

        if (!node) {
          return;
        }
        const { x: prevX, y: prevY, width: prevWidth, height: prevHeight } = prevValues;
        const change: XYResizerChange = {};
        const nodeOrigin = node.origin ?? storeNodeOrigin;

        const { width, height, x, y } = getDimensionsAfterResize(
          startValues,
          controlDirection,
          pointerPosition,
          boundaries,
          keepAspectRatio,
          nodeOrigin,
          parentExtent,
          childExtent
        );

        const isWidthChange = width !== prevWidth;
        const isHeightChange = height !== prevHeight;

        const isXPosChange = x !== prevX && isWidthChange;
        const isYPosChange = y !== prevY && isHeightChange;

        if (!isXPosChange && !isYPosChange && !isWidthChange && !isHeightChange) {
          return;
        }

        if (isXPosChange || isYPosChange || nodeOrigin[0] === 1 || nodeOrigin[1] === 1) {
          change.x = isXPosChange ? x : prevValues.x;
          change.y = isYPosChange ? y : prevValues.y;

          prevValues.x = change.x;
          prevValues.y = change.y;

          // when top/left changes, correct the relative positions of child nodes
          // so that they stay in the same position
          if (childNodes.length > 0) {
            const xChange = x - prevX;
            const yChange = y - prevY;

            for (const childNode of childNodes) {
              childNode.position = {
                x: childNode.position.x - xChange + nodeOrigin[0] * (width - prevWidth),
                y: childNode.position.y - yChange + nodeOrigin[1] * (height - prevHeight),
              };
              childChanges.push(childNode);
            }
          }
        }

        if (isWidthChange || isHeightChange) {
          change.width = isWidthChange ? width : prevValues.width;
          change.height = isHeightChange ? height : prevValues.height;
          prevValues.width = change.width;
          prevValues.height = change.height;
        }

        // Fix expandParent when resizing from top/left
        if (parentNode && node.expandParent) {
          const xLimit = nodeOrigin[0] * (change.width ?? 0);
          if (change.x && change.x < xLimit) {
            prevValues.x = xLimit;
            startValues.x = startValues.x - (change.x - xLimit);
          }

          const yLimit = nodeOrigin[1] * (change.height ?? 0);
          if (change.y && change.y < yLimit) {
            prevValues.y = yLimit;
            startValues.y = startValues.y - (change.y - yLimit);
          }
        }

        const direction = getResizeDirection({
          width: prevValues.width,
          prevWidth,
          height: prevValues.height,
          prevHeight,
          affectsX: controlDirection.affectsX,
          affectsY: controlDirection.affectsY,
        });

        const nextValues = { ...prevValues, direction };

        const callResize = shouldResize?.(event, nextValues);

        if (callResize === false) {
          return;
        }

        onResize?.(event, nextValues);
        onChange(change, childChanges);
      })
      .on('end', (event: ResizeDragEvent) => {
        onResizeEnd?.(event, { ...prevValues });
        onEnd?.();
      });
    selection.call(dragHandler);
  }
  function destroy() {
    selection.on('.drag', null);
  }

  return {
    update,
    destroy,
  };
}