Files
excalidraw/packages/deltas/src/containers/elements.ts
T
2025-03-28 13:23:34 +01:00

826 lines
28 KiB
TypeScript

import { Delta } from "../common/delta";
import { newElementWith, shouldThrow } from "../common/utils";
import type { DeltaContainer } from "../common/interfaces";
import type {
ExcalidrawElement,
ElementUpdate,
Ordered,
SceneElementsMap,
DTO,
OrderedExcalidrawElement,
ExcalidrawImageElement,
} from "../excalidraw-types";
// CFDO: consider adding here (nonnullable) version & versionNonce & updated (so that we have correct versions when recunstructing from remote)
type ElementPartial<T extends ExcalidrawElement = ExcalidrawElement> =
ElementUpdate<Ordered<T>>;
/**
* Elements delta is a low level primitive to encapsulate property changes between two sets of elements.
* It does so by encapsulating forward and backward `Delta`s, allowing to time-travel in both directions.
*/
export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
private constructor(
public readonly added: Record<string, Delta<ElementPartial>>,
public readonly removed: Record<string, Delta<ElementPartial>>,
public readonly updated: Record<string, Delta<ElementPartial>>,
) {}
public static create(
added: Record<string, Delta<ElementPartial>>,
removed: Record<string, Delta<ElementPartial>>,
updated: Record<string, Delta<ElementPartial>>,
options: {
shouldRedistribute: boolean;
} = {
shouldRedistribute: false,
// CFDO: don't forget to re-enable
},
) {
const { shouldRedistribute } = options;
let delta: ElementsDelta;
if (shouldRedistribute) {
const nextAdded: Record<string, Delta<ElementPartial>> = {};
const nextRemoved: Record<string, Delta<ElementPartial>> = {};
const nextUpdated: Record<string, Delta<ElementPartial>> = {};
const deltas = [
...Object.entries(added),
...Object.entries(removed),
...Object.entries(updated),
];
for (const [id, delta] of deltas) {
if (this.satisfiesAddition(delta)) {
nextAdded[id] = delta;
} else if (this.satisfiesRemoval(delta)) {
nextRemoved[id] = delta;
} else {
nextUpdated[id] = delta;
}
}
delta = new ElementsDelta(nextAdded, nextRemoved, nextUpdated);
} else {
delta = new ElementsDelta(added, removed, updated);
}
if (shouldThrow()) {
ElementsDelta.validate(delta, "added", this.satisfiesAddition);
ElementsDelta.validate(delta, "removed", this.satisfiesRemoval);
ElementsDelta.validate(delta, "updated", this.satisfiesUpdate);
}
return delta;
}
public static restore(elementsDeltaDTO: DTO<ElementsDelta>): ElementsDelta {
const { added, removed, updated } = elementsDeltaDTO;
return ElementsDelta.create(added, removed, updated);
}
private static satisfiesAddition = ({
deleted,
inserted,
}: Delta<ElementPartial>) =>
// dissallowing added as "deleted", which could cause issues when resolving conflicts
deleted.isDeleted === true && !inserted.isDeleted;
private static satisfiesRemoval = ({
deleted,
inserted,
}: Delta<ElementPartial>) =>
!deleted.isDeleted && inserted.isDeleted === true;
private static satisfiesUpdate = ({
deleted,
inserted,
}: Delta<ElementPartial>) => !!deleted.isDeleted === !!inserted.isDeleted;
private static validate(
elementsDelta: ElementsDelta,
type: "added" | "removed" | "updated",
satifies: (delta: Delta<ElementPartial>) => boolean,
) {
for (const [id, delta] of Object.entries(elementsDelta[type])) {
if (!satifies(delta)) {
console.error(
`Broken invariant for "${type}" delta, element "${id}", delta:`,
delta,
);
throw new Error(`ElementsDelta invariant broken for element "${id}".`);
}
}
}
/**
* Calculates the `Delta`s between the previous and next set of elements.
*
* @param prevElements - Map representing the previous state of elements.
* @param nextElements - Map representing the next state of elements.
*
* @returns `ElementsDelta` instance representing the `Delta` changes between the two sets of elements.
*/
public static calculate<T extends OrderedExcalidrawElement>(
prevElements: Map<string, T>,
nextElements: Map<string, T>,
): ElementsDelta {
if (prevElements === nextElements) {
return ElementsDelta.empty();
}
const added: Record<string, Delta<ElementPartial>> = {};
const removed: Record<string, Delta<ElementPartial>> = {};
const updated: Record<string, Delta<ElementPartial>> = {};
// this might be needed only in same edge cases, like during collab, when `isDeleted` elements get removed or when we (un)intentionally remove the elements
for (const prevElement of prevElements.values()) {
const nextElement = nextElements.get(prevElement.id);
if (!nextElement) {
const deleted = { ...prevElement, isDeleted: false } as ElementPartial;
const inserted = { isDeleted: true } as ElementPartial;
const delta = Delta.create(
deleted,
inserted,
ElementsDelta.stripIrrelevantProps,
);
removed[prevElement.id] = delta;
}
}
for (const nextElement of nextElements.values()) {
const prevElement = prevElements.get(nextElement.id);
if (!prevElement) {
const deleted = { isDeleted: true } as ElementPartial;
const inserted = {
...nextElement,
isDeleted: false,
} as ElementPartial;
const delta = Delta.create(
deleted,
inserted,
ElementsDelta.stripIrrelevantProps,
);
added[nextElement.id] = delta;
continue;
}
if (prevElement.versionNonce !== nextElement.versionNonce) {
const delta = Delta.calculate<ElementPartial>(
prevElement,
nextElement,
ElementsDelta.stripIrrelevantProps,
ElementsDelta.postProcess,
);
if (
// making sure we don't get here some non-boolean values (i.e. undefined, null, etc.)
typeof prevElement.isDeleted === "boolean" &&
typeof nextElement.isDeleted === "boolean" &&
prevElement.isDeleted !== nextElement.isDeleted
) {
// notice that other props could have been updated as well
if (prevElement.isDeleted && !nextElement.isDeleted) {
added[nextElement.id] = delta;
} else {
removed[nextElement.id] = delta;
}
continue;
}
// making sure there are at least some changes
if (!Delta.isEmpty(delta)) {
updated[nextElement.id] = delta;
}
}
}
return ElementsDelta.create(added, removed, updated);
}
public static empty() {
return ElementsDelta.create({}, {}, {});
}
public inverse(): ElementsDelta {
const inverseInternal = (deltas: Record<string, Delta<ElementPartial>>) => {
const inversedDeltas: Record<string, Delta<ElementPartial>> = {};
for (const [id, delta] of Object.entries(deltas)) {
inversedDeltas[id] = Delta.create(delta.inserted, delta.deleted);
}
return inversedDeltas;
};
const added = inverseInternal(this.added);
const removed = inverseInternal(this.removed);
const updated = inverseInternal(this.updated);
// notice we inverse removed with added not to break the invariants
// notice we force generate a new id
return ElementsDelta.create(removed, added, updated);
}
public isEmpty(): boolean {
return (
Object.keys(this.added).length === 0 &&
Object.keys(this.removed).length === 0 &&
Object.keys(this.updated).length === 0
);
}
/**
* Update delta/s based on the existing elements.
*
* @param elements current elements
* @param modifierOptions defines which of the delta (`deleted` or `inserted`) will be updated
* @returns new instance with modified delta/s
*/
public applyLatestChanges(
elements: SceneElementsMap,
modifierOptions: "deleted" | "inserted",
): ElementsDelta {
const modifier =
(element: OrderedExcalidrawElement) => (partial: ElementPartial) => {
const latestPartial: { [key: string]: unknown } = {};
for (const key of Object.keys(partial) as Array<keyof typeof partial>) {
// do not update following props:
// - `boundElements`, as it is a reference value which is postprocessed to contain only deleted/inserted keys
switch (key) {
case "boundElements":
latestPartial[key] = partial[key];
break;
default:
latestPartial[key] = element[key];
}
}
return latestPartial;
};
const applyLatestChangesInternal = (
deltas: Record<string, Delta<ElementPartial>>,
) => {
const modifiedDeltas: Record<string, Delta<ElementPartial>> = {};
for (const [id, delta] of Object.entries(deltas)) {
const existingElement = elements.get(id);
if (existingElement) {
const modifiedDelta = Delta.create(
delta.deleted,
delta.inserted,
modifier(existingElement),
modifierOptions,
);
modifiedDeltas[id] = modifiedDelta;
} else {
modifiedDeltas[id] = delta;
}
}
return modifiedDeltas;
};
const added = applyLatestChangesInternal(this.added);
const removed = applyLatestChangesInternal(this.removed);
const updated = applyLatestChangesInternal(this.updated);
return ElementsDelta.create(added, removed, updated, {
shouldRedistribute: true, // redistribute the deltas as `isDeleted` could have been updated
});
}
// CFDO: does it make sense having a separate snapshot?
public applyTo(
elements: SceneElementsMap,
elementsSnapshot: Map<string, OrderedExcalidrawElement>,
): [SceneElementsMap, boolean] {
const nextElements = new Map(elements) as SceneElementsMap;
let changedElements: Map<string, OrderedExcalidrawElement>;
const flags = {
containsVisibleDifference: false,
containsZindexDifference: false,
};
// mimic a transaction by applying deltas into `nextElements` (always new instance, no mutation)
try {
const applyDeltas = ElementsDelta.createApplier(
nextElements,
elementsSnapshot,
flags,
);
const addedElements = applyDeltas("added", this.added);
const removedElements = applyDeltas("removed", this.removed);
const updatedElements = applyDeltas("updated", this.updated);
// CFDO I: don't forget to fix this part
// const affectedElements = this.resolveConflicts(elements, nextElements);
// TODO: #7348 validate elements semantically and syntactically the changed elements, in case they would result data integrity issues
changedElements = new Map([
...addedElements,
...removedElements,
...updatedElements,
// ...affectedElements,
]);
} catch (e) {
console.error(`Couldn't apply elements delta`, e);
if (shouldThrow()) {
throw e;
}
// should not really happen, but just in case we cannot apply deltas, let's return the previous elements with visible change set to `true`
// even though there is obviously no visible change, returning `false` could be dangerous, as i.e.:
// in the worst case, it could lead into iterating through the whole stack with no possibility to redo
// instead, the worst case when returning `true` is an empty undo / redo
return [elements, true];
}
try {
// CFDO I: don't forget to fix this part
// // TODO: #7348 refactor away mutations below, so that we couldn't end up in an incosistent state
// ElementsDelta.redrawTextBoundingBoxes(nextElements, changedElements);
// // the following reorder performs also mutations, but only on new instances of changed elements
// // (unless something goes really bad and it fallbacks to fixing all invalid indices)
// nextElements = ElementsDelta.reorderElements(
// nextElements,
// changedElements,
// flags,
// );
// // Need ordered nextElements to avoid z-index binding issues
// ElementsDelta.redrawBoundArrows(nextElements, changedElements);
} catch (e) {
console.error(
`Couldn't mutate elements after applying elements change`,
e,
);
if (shouldThrow()) {
throw e;
}
} finally {
return [nextElements, flags.containsVisibleDifference];
}
}
private static createApplier =
(
nextElements: SceneElementsMap,
snapshot: Map<string, OrderedExcalidrawElement>,
flags: {
containsVisibleDifference: boolean;
containsZindexDifference: boolean;
},
) =>
(
type: "added" | "removed" | "updated",
deltas: Record<string, Delta<ElementPartial>>,
) => {
const getElement = ElementsDelta.createGetter(
type,
nextElements,
snapshot,
flags,
);
return Object.entries(deltas).reduce((acc, [id, delta]) => {
const element = getElement(id, delta.inserted);
if (element) {
const newElement = ElementsDelta.applyDelta(element, delta, flags);
nextElements.set(newElement.id, newElement);
acc.set(newElement.id, newElement);
}
return acc;
}, new Map<string, OrderedExcalidrawElement>());
};
private static createGetter =
(
type: "added" | "removed" | "updated",
elements: SceneElementsMap,
snapshot: Map<string, OrderedExcalidrawElement>,
flags: {
containsVisibleDifference: boolean;
containsZindexDifference: boolean;
},
) =>
(id: string, partial: ElementPartial) => {
let element = elements.get(id);
if (!element) {
// always fallback to the local snapshot, in cases when we cannot find the element in the elements array
element = snapshot.get(id);
if (element) {
// as the element was brought from the snapshot, it automatically results in a possible zindex difference
flags.containsZindexDifference = true;
// as the element was force deleted, we need to check if adding it back results in a visible change
if (
partial.isDeleted === false ||
(partial.isDeleted !== true && element.isDeleted === false)
) {
flags.containsVisibleDifference = true;
}
} else if (type === "added") {
// for additions the element does not have to exist (i.e. remote update)
// CFDO II: the version itself might be different!
element = newElementWith(
{ id, version: 1 } as OrderedExcalidrawElement,
{
...partial,
},
);
}
}
return element;
};
private static applyDelta(
element: OrderedExcalidrawElement,
delta: Delta<ElementPartial>,
flags: {
containsVisibleDifference: boolean;
containsZindexDifference: boolean;
} = {
// by default we don't care about about the flags
containsVisibleDifference: true,
containsZindexDifference: true,
},
) {
const { boundElements, ...directlyApplicablePartial } = delta.inserted;
if (
delta.deleted.boundElements?.length ||
delta.inserted.boundElements?.length
) {
const mergedBoundElements = Delta.mergeArrays(
element.boundElements,
delta.inserted.boundElements,
delta.deleted.boundElements,
(x) => x.id,
);
Object.assign(directlyApplicablePartial, {
boundElements: mergedBoundElements,
});
}
// CFDO: this looks wrong
if (element.type === "image") {
const _delta = delta as Delta<ElementPartial<ExcalidrawImageElement>>;
// we want to override `crop` only if modified so that we don't reset
// when undoing/redoing unrelated change
if (_delta.deleted.crop || _delta.inserted.crop) {
Object.assign(directlyApplicablePartial, {
// apply change verbatim
crop: _delta.inserted.crop ?? null,
});
}
}
if (!flags.containsVisibleDifference) {
// strip away fractional index, as even if it would be different, it doesn't have to result in visible change
const { index, ...rest } = directlyApplicablePartial;
const containsVisibleDifference = ElementsDelta.checkForVisibleDifference(
element,
rest,
);
flags.containsVisibleDifference = containsVisibleDifference;
}
if (!flags.containsZindexDifference) {
flags.containsZindexDifference =
delta.deleted.index !== delta.inserted.index;
}
return newElementWith(element, directlyApplicablePartial);
}
/**
* Check for visible changes regardless of whether they were removed, added or updated.
*/
private static checkForVisibleDifference(
element: OrderedExcalidrawElement,
partial: ElementPartial,
) {
if (element.isDeleted && partial.isDeleted !== false) {
// when it's deleted and partial is not false, it cannot end up with a visible change
return false;
}
if (element.isDeleted && partial.isDeleted === false) {
// when we add an element, it results in a visible change
return true;
}
if (element.isDeleted === false && partial.isDeleted) {
// when we remove an element, it results in a visible change
return true;
}
// check for any difference on a visible element
return Delta.isRightDifferent(element, partial);
}
// /**
// * Resolves conflicts for all previously added, removed and updated elements.
// * Updates the previous deltas with all the changes after conflict resolution.
// *
// * // CFDO: revisit since arrow seem often redrawn incorrectly
// *
// * @returns all elements affected by the conflict resolution
// */
// private resolveConflicts(
// prevElements: SceneElementsMap,
// nextElements: SceneElementsMap,
// ) {
// const nextAffectedElements = new Map<string, OrderedExcalidrawElement>();
// const updater = (
// element: ExcalidrawElement,
// updates: ElementUpdate<ExcalidrawElement>,
// ) => {
// const nextElement = nextElements.get(element.id); // only ever modify next element!
// if (!nextElement) {
// return;
// }
// let affectedElement: OrderedExcalidrawElement;
// if (prevElements.get(element.id) === nextElement) {
// // create the new element instance in case we didn't modify the element yet
// // so that we won't end up in an incosistent state in case we would fail in the middle of mutations
// affectedElement = newElementWith(
// nextElement,
// updates as ElementUpdate<OrderedExcalidrawElement>,
// );
// } else {
// affectedElement = mutateElement(
// nextElement,
// updates as ElementUpdate<OrderedExcalidrawElement>,
// );
// }
// nextAffectedElements.set(affectedElement.id, affectedElement);
// nextElements.set(affectedElement.id, affectedElement);
// };
// // removed delta is affecting the bindings always, as all the affected elements of the removed elements need to be unbound
// for (const id of Object.keys(this.removed)) {
// ElementsDelta.unbindAffected(prevElements, nextElements, id, updater);
// }
// // added delta is affecting the bindings always, all the affected elements of the added elements need to be rebound
// for (const id of Object.keys(this.added)) {
// ElementsDelta.rebindAffected(prevElements, nextElements, id, updater);
// }
// // updated delta is affecting the binding only in case it contains changed binding or bindable property
// for (const [id] of Array.from(Object.entries(this.updated)).filter(
// ([_, delta]) =>
// Object.keys({ ...delta.deleted, ...delta.inserted }).find((prop) =>
// bindingProperties.has(prop as BindingProp | BindableProp),
// ),
// )) {
// const updatedElement = nextElements.get(id);
// if (!updatedElement || updatedElement.isDeleted) {
// // skip fixing bindings for updates on deleted elements
// continue;
// }
// ElementsDelta.rebindAffected(prevElements, nextElements, id, updater);
// }
// // filter only previous elements, which were now affected
// const prevAffectedElements = new Map(
// Array.from(prevElements).filter(([id]) => nextAffectedElements.has(id)),
// );
// // calculate complete deltas for affected elements, and assign them back to all the deltas
// // technically we could do better here if perf. would become an issue
// const { added, removed, updated } = ElementsDelta.calculate(
// prevAffectedElements,
// nextAffectedElements,
// );
// for (const [id, delta] of Object.entries(added)) {
// this.added[id] = delta;
// }
// for (const [id, delta] of Object.entries(removed)) {
// this.removed[id] = delta;
// }
// for (const [id, delta] of Object.entries(updated)) {
// this.updated[id] = delta;
// }
// return nextAffectedElements;
// }
// /**
// * Non deleted affected elements of removed elements (before and after applying delta),
// * should be unbound ~ bindings should not point from non deleted into the deleted element/s.
// */
// private static unbindAffected(
// prevElements: SceneElementsMap,
// nextElements: SceneElementsMap,
// id: string,
// updater: (
// element: ExcalidrawElement,
// updates: ElementUpdate<ExcalidrawElement>,
// ) => void,
// ) {
// // the instance could have been updated, so make sure we are passing the latest element to each function below
// const prevElement = () => prevElements.get(id); // element before removal
// const nextElement = () => nextElements.get(id); // element after removal
// BoundElement.unbindAffected(nextElements, prevElement(), updater);
// BoundElement.unbindAffected(nextElements, nextElement(), updater);
// BindableElement.unbindAffected(nextElements, prevElement(), updater);
// BindableElement.unbindAffected(nextElements, nextElement(), updater);
// }
// /**
// * Non deleted affected elements of added or updated element/s (before and after applying delta),
// * should be rebound (if possible) with the current element ~ bindings should be bidirectional.
// */
// private static rebindAffected(
// prevElements: SceneElementsMap,
// nextElements: SceneElementsMap,
// id: string,
// updater: (
// element: ExcalidrawElement,
// updates: ElementUpdate<ExcalidrawElement>,
// ) => void,
// ) {
// // the instance could have been updated, so make sure we are passing the latest element to each function below
// const prevElement = () => prevElements.get(id); // element before addition / update
// const nextElement = () => nextElements.get(id); // element after addition / update
// BoundElement.unbindAffected(nextElements, prevElement(), updater);
// BoundElement.rebindAffected(nextElements, nextElement(), updater);
// BindableElement.unbindAffected(
// nextElements,
// prevElement(),
// (element, updates) => {
// // we cannot rebind arrows with bindable element so we don't unbind them at all during rebind (we still need to unbind them on removal)
// // TODO: #7348 add startBinding / endBinding to the `BoundElement` context so that we could rebind arrows and remove this condition
// if (isTextElement(element)) {
// updater(element, updates);
// }
// },
// );
// BindableElement.rebindAffected(nextElements, nextElement(), updater);
// }
// private static redrawTextBoundingBoxes(
// elements: SceneElementsMap,
// changed: Map<string, OrderedExcalidrawElement>,
// ) {
// const boxesToRedraw = new Map<
// string,
// { container: OrderedExcalidrawElement; boundText: ExcalidrawTextElement }
// >();
// for (const element of changed.values()) {
// if (isBoundToContainer(element)) {
// const { containerId } = element as ExcalidrawTextElement;
// const container = containerId ? elements.get(containerId) : undefined;
// if (container) {
// boxesToRedraw.set(container.id, {
// container,
// boundText: element as ExcalidrawTextElement,
// });
// }
// }
// if (hasBoundTextElement(element)) {
// const boundTextElementId = getBoundTextElementId(element);
// const boundText = boundTextElementId
// ? elements.get(boundTextElementId)
// : undefined;
// if (boundText) {
// boxesToRedraw.set(element.id, {
// container: element,
// boundText: boundText as ExcalidrawTextElement,
// });
// }
// }
// }
// for (const { container, boundText } of boxesToRedraw.values()) {
// if (container.isDeleted || boundText.isDeleted) {
// // skip redraw if one of them is deleted, as it would not result in a meaningful redraw
// continue;
// }
// redrawTextBoundingBox(boundText, container, elements, false);
// }
// }
// private static redrawBoundArrows(
// elements: SceneElementsMap,
// changed: Map<string, OrderedExcalidrawElement>,
// ) {
// for (const element of changed.values()) {
// if (!element.isDeleted && isBindableElement(element)) {
// updateBoundElements(element, elements, {
// changedElements: changed,
// });
// }
// }
// }
// private static reorderElements(
// elements: SceneElementsMap,
// changed: Map<string, OrderedExcalidrawElement>,
// flags: {
// containsVisibleDifference: boolean;
// containsZindexDifference: boolean;
// },
// ) {
// if (!flags.containsZindexDifference) {
// return elements;
// }
// const unordered = Array.from(elements.values());
// const ordered = orderByFractionalIndex([...unordered]);
// const moved = Delta.getRightDifferences(unordered, ordered, true).reduce(
// (acc, arrayIndex) => {
// const candidate = unordered[Number(arrayIndex)];
// if (candidate && changed.has(candidate.id)) {
// acc.set(candidate.id, candidate);
// }
// return acc;
// },
// new Map(),
// );
// if (!flags.containsVisibleDifference && moved.size) {
// // we found a difference in order!
// flags.containsVisibleDifference = true;
// }
// // synchronize all elements that were actually moved
// // could fallback to synchronizing all invalid indices
// return elementsToMap(syncMovedIndices(ordered, moved)) as typeof elements;
// }
/**
* It is necessary to post process the partials in case of reference values,
* for which we need to calculate the real diff between `deleted` and `inserted`.
*/
private static postProcess(
deleted: ElementPartial,
inserted: ElementPartial,
): [ElementPartial, ElementPartial] {
try {
Delta.diffArrays(deleted, inserted, "boundElements", (x) => x.id);
} catch (e) {
// if postprocessing fails, it does not make sense to bubble up, but let's make sure we know about it
console.error(`Couldn't postprocess elements delta.`);
if (shouldThrow()) {
throw e;
}
} finally {
return [deleted, inserted];
}
}
private static stripIrrelevantProps(
partial: Partial<OrderedExcalidrawElement>,
): ElementPartial {
const { id, updated, version, versionNonce, ...strippedPartial } = partial;
return strippedPartial;
}
}