# 版本

> 给编辑器加上画布版本历史：保存命名版本，每隔几次保存自动留一个版本，恢复版本时不丢任何内容。

Source: https://fabricjs-document-engine.jscrate.dev/zh/docs/guides/versions
Last updated: 2026-09-28

撤销只覆盖最近几分钟。画布版本历史能把你选定的状态保留几天甚至几个月，比如「已发给客户」。版本是文档的完整副本，保存在你的存储适配器里。

```tsx
"use client";

import type { VersionSummary } from "fabricjs-document-engine";
import { useDocumentEngine } from "fabricjs-document-engine/react";
import { createMemoryStorage } from "fabricjs-document-engine/storage";
import { BookmarkPlusIcon, CircleIcon, SquareIcon } from "lucide-react";
import { useFormatter, useTranslations } from "next-intl";
import { useEffect, useState } from "react";

import {
  DemoCanvas,
  DemoFrame,
  newShape,
  seedShapes,
  Toolbar,
  ToolButton,
} from "./demo-ui";
import { useFabricCanvas } from "./use-fabric-canvas";

const storage = createMemoryStorage();

export default function VersionsDemo() {
  const t = useTranslations("demos");
  const format = useFormatter();
  const { elementRef, canvas } = useFabricCanvas();
  const engine = useDocumentEngine(canvas, { storage });
  const [versions, setVersions] = useState<VersionSummary[]>([]);

  useEffect(() => {
    if (!engine) return;
    engine.canvas.add(...seedShapes());
    engine.clearHistory();
  }, [engine]);

  async function keepVersion() {
    if (!engine) return;
    await engine.save();
    await engine.createVersion(
      t("versions.name", { number: versions.length + 1 })
    );
    setVersions(await namedVersions());
  }

  async function restore(id: string) {
    if (!engine) return;
    await engine.restoreVersion(id);
    await engine.save();
    setVersions(await namedVersions());
  }

  // The engine also keeps automatic versions; this list shows the named ones.
  async function namedVersions() {
    const all = (await engine?.listVersions()) ?? [];
    return all.filter((version) => version.kind === "named");
  }

  return (
    <DemoFrame>
      <DemoCanvas elementRef={elementRef} label={t("canvas")} />

      <Toolbar>
        <ToolButton
          icon={SquareIcon}
          label={t("square")}
          onClick={() => canvas?.add(newShape("square"))}
        />
        <ToolButton
          icon={CircleIcon}
          label={t("circle")}
          onClick={() => canvas?.add(newShape("circle"))}
        />
        <ToolButton
          icon={BookmarkPlusIcon}
          label={t("versions.keep")}
          primary
          disabled={!engine}
          className="ml-auto"
          onClick={() => void keepVersion()}
        />
      </Toolbar>

      {/* A fixed height: the list scrolls instead of growing the card. */}
      <ul className="h-[92px] overflow-y-auto rounded-lg border text-[13px]">
        {versions.length === 0 && (
          <li className="px-3 py-2 text-muted-foreground">
            {t("versions.empty")}
          </li>
        )}
        {versions.map((version) => (
          <li
            key={version.id}
            className="flex h-[30px] items-center gap-2 border-b px-3 last:border-b-0"
          >
            <span className="truncate font-medium">{version.name}</span>
            <span className="text-muted-foreground">
              {format.dateTime(new Date(version.createdAt), {
                timeStyle: "medium",
              })}
            </span>
            <button
              type="button"
              className="ml-auto shrink-0 font-medium text-[#6f00ff] hover:underline"
              onClick={() => void restore(version.id)}
            >
              {t("versions.restore")}
            </button>
          </li>
        ))}
      </ul>
    </DemoFrame>
  );
}
```

```tsx
import { Canvas } from "fabric";
import { useLayoutEffect, useRef, useState } from "react";

/**
 * The page every demo draws on. The document keeps this size; CSS scales the
 * canvas down to fit its card, so saved documents and exports never depend on
 * the screen.
 */
export const PAGE = { width: 480, height: 300 };

// Selection handles in the site's style. Fabric does not save these.
const SELECTION = {
  borderColor: "#6f00ff",
  borderScaleFactor: 1.5,
  borderOpacityWhenMoving: 0.5,
  cornerStyle: "circle",
  cornerSize: 11,
  cornerColor: "#ffffff",
  cornerStrokeColor: "#6f00ff",
  transparentCorners: false,
} as const;

export function styleSelection(canvas: Canvas) {
  canvas.set({
    selectionColor: "rgba(111, 0, 255, 0.06)",
    selectionBorderColor: "#6f00ff",
    selectionLineWidth: 1,
  });
  const style = () => canvas.getActiveObject()?.set(SELECTION);
  canvas.on("selection:created", style);
  canvas.on("selection:updated", style);
}

/**
 * Creates a Fabric.js canvas once the `<canvas>` element exists, and disposes
 * it on unmount. The engine is created from the returned `canvas`.
 */
export function useFabricCanvas({ width, height } = PAGE) {
  const elementRef = useRef<HTMLCanvasElement>(null);
  const [canvas, setCanvas] = useState<Canvas | null>(null);

  // A layout effect creates the canvas before the first paint.
  useLayoutEffect(() => {
    const created = new Canvas(elementRef.current!, {
      width,
      height,
      backgroundColor: "#ffffff",
    });
    styleSelection(created);
    setCanvas(created);

    return () => {
      // Dispose after the engine's own cleanup, so its last recovery copy
      // still sees the objects.
      setTimeout(() => created.dispose().catch(() => undefined));
    };
  }, [width, height]);

  return { elementRef, canvas };
}
```

```tsx
import { Circle, type FabricObject, Rect, Triangle } from "fabric";
import type { LucideIcon } from "lucide-react";

import { cn } from "@/lib/utils";

import { PAGE } from "./use-fabric-canvas";

export const COLORS = ["#f2836f", "#5fe6c4", "#7ad9ec", "#6f00ff", "#ffd666"];

// Demo shapes are placed by their top-left corner, like a design tool.
const CORNER = { originX: "left", originY: "top" } as const;

/** A new shape at a random spot on the page. */
export function newShape(kind: "square" | "circle", fill?: string) {
  const left = 40 + Math.random() * (PAGE.width - 160);
  const top = 30 + Math.random() * (PAGE.height - 120);
  const color = fill ?? COLORS[Math.floor(Math.random() * COLORS.length)];
  return kind === "square"
    ? new Rect({
        ...CORNER,
        left,
        top,
        width: 88,
        height: 64,
        rx: 10,
        ry: 10,
        fill: color,
      })
    : new Circle({ ...CORNER, left, top, radius: 34, fill: color });
}

/** A small composed drawing, so no demo starts on an empty page. */
export function seedShapes(): FabricObject[] {
  return [
    new Rect({
      ...CORNER,
      left: 48,
      top: 56,
      width: 176,
      height: 124,
      rx: 16,
      ry: 16,
      fill: COLORS[4],
    }),
    new Circle({ ...CORNER, left: 268, top: 44, radius: 58, fill: COLORS[0] }),
    new Rect({
      ...CORNER,
      left: 256,
      top: 196,
      width: 176,
      height: 52,
      rx: 26,
      ry: 26,
      fill: COLORS[1],
    }),
    new Triangle({
      ...CORNER,
      left: 96,
      top: 196,
      width: 72,
      height: 60,
      fill: COLORS[3],
    }),
  ];
}

export function DemoFrame({
  className,
  ...props
}: React.ComponentProps<"div">) {
  return (
    <div
      className={cn(
        "flex w-full max-w-md flex-col gap-3 text-left outline-none",
        className
      )}
      {...props}
    />
  );
}

/**
 * Scales the fixed-size Fabric canvas to the frame's width. The rules are
 * `!important` because Fabric writes its sizes as inline styles.
 */
export function DemoCanvas({
  elementRef,
  label,
  page = PAGE,
  children,
}: {
  elementRef: React.Ref<HTMLCanvasElement>;
  label: string;
  page?: { width: number; height: number };
  children?: React.ReactNode;
}) {
  return (
    <div
      className="relative overflow-hidden rounded-lg border bg-white shadow-xs [&_.canvas-container]:aspect-(--page)! [&_.canvas-container]:h-auto! [&_.canvas-container]:w-full! [&_canvas]:h-full! [&_canvas]:w-full!"
      style={
        { "--page": `${page.width} / ${page.height}` } as React.CSSProperties
      }
    >
      <div>
        <canvas ref={elementRef} aria-label={label} />
      </div>
      {children}
    </div>
  );
}

export function Toolbar({ className, ...props }: React.ComponentProps<"div">) {
  return (
    <div
      className={cn("flex flex-wrap items-center gap-1.5", className)}
      {...props}
    />
  );
}

export function ToolButton({
  icon: Icon,
  label,
  iconOnly = false,
  primary = false,
  className,
  ...props
}: React.ComponentProps<"button"> & {
  icon: LucideIcon;
  label: string;
  iconOnly?: boolean;
  primary?: boolean;
}) {
  return (
    <button
      type="button"
      title={label}
      aria-label={iconOnly ? label : undefined}
      className={cn(
        "inline-flex h-8 min-w-0 items-center justify-center gap-1.5 rounded-md border px-2.5 text-[13px] font-medium whitespace-nowrap transition-colors disabled:pointer-events-none disabled:opacity-40 [&_svg]:size-3.5 [&_svg]:shrink-0",
        primary
          ? "border-transparent bg-foreground text-background hover:bg-foreground/85"
          : "bg-background hover:bg-muted",
        iconOnly && "w-8 px-0",
        className
      )}
      {...props}
    >
      <Icon aria-hidden />
      {!iconOnly && <span className="truncate">{label}</span>}
    </button>
  );
}

const TONES = {
  idle: "bg-zinc-400",
  busy: "bg-amber-400",
  ok: "bg-emerald-500",
  error: "bg-red-500",
};

/** One line of status text. Its height never changes, so the card never jumps. */
export function Status({
  tone = "idle",
  children,
}: {
  tone?: keyof typeof TONES;
  children: React.ReactNode;
}) {
  return (
    <p
      role="status"
      className="flex h-5 min-w-0 items-center gap-2 text-[13px] text-muted-foreground"
    >
      <span
        aria-hidden
        className={cn("size-1.5 shrink-0 rounded-full", TONES[tone])}
      />
      <span className="truncate">{children}</span>
    </p>
  );
}
```

## 保存和列出版本

```ts
const version = await engine.createVersion("Sent to client");
const versions = await engine.listVersions();
```

`listVersions` 返回版本摘要，最新的在前：`{ id, documentId, name, kind, createdAt, revision }`。`kind` 为 `named` 表示命名版本，为 `auto` 表示自动版本。

## 恢复版本

```ts
await engine.restoreVersion(version.id);
```

恢复版本时不会丢任何内容：

1. 引擎先保存一个名为 `Before restoring "..."` 的自动版本。
2. 然后把旧内容作为同一份文档的一个新的、未保存的修订加载进来。
3. 下一次保存会把它存为最新修订，所以画布版本历史始终是线性的。

想撤销这次恢复，恢复那个自动版本就行。

## 自动版本

```ts
createDocumentEngine({
  canvas,
  storage,
  versions: { autoEvery: 10, keepAuto: 20 },
});
```

这样每成功保存 10 次就会留一个自动版本，并且只保留最新的 20 个自动版本。命名版本永远不会被清理。

## 删除版本

```ts
await engine.deleteVersion(version.id);
```

## 存储支持

内置适配器都支持版本。自定义适配器需要多实现四个方法：`saveVersion`、`listVersions`、`loadVersion` 和 `deleteVersion`。缺少它们时，版本相关的调用会以 `VERSIONS_UNSUPPORTED` 失败。想给你自己的 API 加上画布版本历史，请看[自定义后端](https://fabricjs-document-engine.jscrate.dev/zh/docs/storage/custom-backend)。