feuerwerk/tests/core/pixel-art.test.ts

/**
 * Pixel art (#130): the cel format and its name, the drawing rules, how layers make a frame, the
 * edits and the one command that takes them back, the project file, and the picture path.
 */
import { describe, expect, it } from 'vitest';
import { CreateAssetCommand } from '../../src/core/commands/assetCommands';
import { CommandError } from '../../src/core/commands/Command';
import { EditPixelArtCommand, SetPaletteColorsCommand } from '../../src/core/commands/pixelArtCommands';
import type { PaletteAsset, PixelArtAsset } from '../../src/core/model/Asset';
import { registerPictureSource } from '../../src/core/model/generated';
import {
  celFilesOf,
  colorAt,
  composeFrame,
  composeSheet,
  DEFAULT_PALETTE,
  findPixelFrame,
  PALETTE_KEY,
  paletteColors,
  pixelArtPicture,
  pixelArtRevision,
  pixelArtWornId,
} from '../../src/core/model/pixelart';
import {
  type CelPixels,
  celFileName,
  decodeCel,
  emptyCel,
  encodeCel,
  isCelFile,
  sha256Hex,
} from '../../src/core/model/pixelCel';
import {
  anchorOffset,
  ellipsePoints,
  floodFill,
  linePoints,
  mergeCels,
  rectPoints,
  resizeCel,
  stamp,
} from '../../src/core/model/pixelDraw';
import {
  pixelArtState,
  withCanvasSize,
  withCels,
  withFrameAdded,
  withFrameMoved,
  withFrameRemoved,
  withLayerAdded,
  withLayerChanged,
  withLayerMergedDown,
  withLayerMoved,
  withLayerRemoved,
} from '../../src/core/model/pixelEdit';
import { findAsset, type Project } from '../../src/core/model/Project';
import { resolvePicture } from '../../src/core/model/texture';
import { pictureChoices, textureRefLabel } from '../../src/core/properties/textureRef';
import type { ProjectStore } from '../../src/core/store/ProjectStore';
import { CelUploadStore } from '../../src/editor/pixelart/celUploadStore';
import { PixelCels } from '../../src/viewport/PixelCels';
import { fitZoom, pixelUnder, stepZoom } from '../../src/editor/pixelart/pixelView';
import { makeProject, roundTrip } from '../helpers';

const FILE_A = `${'a'.repeat(64)}.px`;
const FILE_B = `${'b'.repeat(64)}.px`;

function cel(width: number, height: number, rows: number[][]): CelPixels {
  return { width, height, data: Uint8Array.from(rows.flat()) };
}

function art(project: Project): PixelArtAsset {
  const create = new CreateAssetCommand('pixelart', 'Art');
  create.execute(project);
  return create.asset as PixelArtAsset;
}

describe('cel files', () => {
  it('hashes like SHA-256', () => {
    expect(sha256Hex(new Uint8Array())).toBe(
      'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855',
    );
    expect(sha256Hex(new TextEncoder().encode('abc'))).toBe(
      'ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad',
    );
    // Two blocks: the padding has to spill into a second one.
    expect(sha256Hex(new TextEncoder().encode('a'.repeat(64)))).toBe(
      'ffe054fe7ae0cb6dc65c3af9b61d5209f439851db43d0ba5997337df154668eb',
    );
  });

  it('writes a header the server checks and reads it back', () => {
    const pixels = cel(3, 2, [
      [1, 0, 2],
      [0, 3, 0],
    ]);
    const bytes = encodeCel(pixels);
    expect([...bytes.slice(0, 10)]).toEqual([0x47, 0x4d, 0x50, 0x58, 1, 0, 3, 0, 2, 0]);
    expect(decodeCel(bytes)).toEqual(pixels);
    expect(isCelFile(celFileName(bytes))).toBe(true);
  });

  it('refuses a cel of the wrong length, version or size', () => {
    const bytes = encodeCel(emptyCel(2, 2));
    expect(decodeCel(bytes.slice(0, -1))).toBeNull();
    const version = bytes.slice();
    version[4] = 2;
    expect(decodeCel(version)).toBeNull();
    const huge = encodeCel(emptyCel(2, 2));
    huge[6] = 0x01;
    huge[7] = 0x02; // 513 wide
    expect(decodeCel(huge)).toBeNull();
  });
});

describe('drawing', () => {
  it('draws a line pixel by pixel, both ends included', () => {
    expect(linePoints({ x: 0, y: 0 }, { x: 3, y: 1 })).toEqual([
      { x: 0, y: 0 },
      { x: 1, y: 0 },
      { x: 2, y: 1 },
      { x: 3, y: 1 },
    ]);
    expect(linePoints({ x: 2, y: 2 }, { x: 2, y: 2 })).toEqual([{ x: 2, y: 2 }]);
  });

  it('draws the border of a rectangle, or all of it', () => {
    expect(rectPoints({ x: 3, y: 3 }, { x: 0, y: 0 }, false)).toHaveLength(12);
    expect(rectPoints({ x: 0, y: 0 }, { x: 3, y: 3 }, true)).toHaveLength(16);
  });

  it('draws an ellipse whose outline has no gaps and whose fill leaves the corners', () => {
    const filled = ellipsePoints({ x: 0, y: 0 }, { x: 7, y: 7 }, true);
    const outline = ellipsePoints({ x: 0, y: 0 }, { x: 7, y: 7 }, false);
    const has = (list: { x: number; y: number }[], x: number, y: number) =>
      list.some((p) => p.x === x && p.y === y);
    expect(has(filled, 0, 0)).toBe(false);
    expect(has(filled, 3, 3)).toBe(true);
    expect(has(outline, 3, 3)).toBe(false);
    expect(has(outline, 0, 3)).toBe(true);
    // Every outline pixel touches another one, so the ring is closed.
    for (const p of outline)
      expect(outline.some((q) => q !== p && Math.abs(q.x - p.x) <= 1 && Math.abs(q.y - p.y) <= 1)).toBe(true);
    // Symmetric in both axes.
    for (const p of filled) expect(has(filled, 7 - p.x, p.y) && has(filled, p.x, 7 - p.y)).toBe(true);
  });

  it('stamps a brush centred on the point, an even one reaching right and down', () => {
    const pixels = emptyCel(6, 6);
    stamp(pixels, { x: 2, y: 2 }, 2, 5);
    expect(pixels.data.reduce((n, i) => n + (i === 5 ? 1 : 0), 0)).toBe(4);
    expect(pixels.data[2 * 6 + 2]).toBe(5);
    expect(pixels.data[3 * 6 + 3]).toBe(5);
    expect(pixels.data[1 * 6 + 1]).toBe(0);
  });

  it('fills the area joined by edges, or every pixel of that colour', () => {
    const rows = [
      [0, 1, 0],
      [1, 0, 0],
      [0, 0, 0],
    ];
    const joined = cel(3, 3, rows);
    floodFill(joined, { x: 2, y: 2 }, 7, true);
    // The corner pixel is cut off by two edges and only touches the area diagonally.
    expect([...joined.data]).toEqual([0, 1, 7, 1, 7, 7, 7, 7, 7]);
    const every = cel(3, 3, rows);
    floodFill(every, { x: 2, y: 2 }, 7, false);
    expect([...every.data]).toEqual([7, 1, 7, 1, 7, 7, 7, 7, 7]);
  });

  it('resizes about an anchor and cuts what sticks out', () => {
    const pixels = cel(2, 2, [
      [1, 2],
      [3, 4],
    ]);
    expect([...resizeCel(pixels, 4, 2, { x: 0.5, y: 0 }).data]).toEqual([0, 1, 2, 0, 0, 3, 4, 0]);
    expect([...resizeCel(pixels, 1, 1, { x: 1, y: 1 }).data]).toEqual([4]);
    expect(anchorOffset(32, 40, 0.5)).toBe(4);
  });

  it('merges a layer down: what the upper one paints covers the lower one', () => {
    const merged = mergeCels(cel(2, 1, [[1, 1]]), cel(2, 1, [[0, 2]]));
    expect([...merged.data]).toEqual([1, 2]);
  });
});

describe('composing', () => {
  const colors = [0xff0000, 0x0000ff];

  it('lays the layers over each other in list order, the last on top', () => {
    const { project } = makeProject();
    const asset = art(project);
    asset.width = 2;
    asset.height = 1;
    asset.layers = [
      { id: 'low', name: 'Low', opacity: 1 },
      { id: 'high', name: 'High', opacity: 1 },
    ];
    asset.frames = [{ id: 'f', cels: { low: FILE_A, high: FILE_B } }];
    const read = (file: string) =>
      file === FILE_A ? cel(2, 1, [[1, 1]]) : file === FILE_B ? cel(2, 1, [[0, 2]]) : null;
    const rgba = composeFrame(asset, colors, asset.frames[0]!, read);
    expect([...rgba!]).toEqual([255, 0, 0, 255, 0, 0, 255, 255]);
  });

  it('mixes a layer by its opacity and leaves a hidden one out', () => {
    const { project } = makeProject();
    const asset = art(project);
    asset.width = 1;
    asset.height = 1;
    asset.layers = [
      { id: 'low', name: 'Low', opacity: 1 },
      { id: 'high', name: 'High', opacity: 0.5 },
    ];
    asset.frames = [{ id: 'f', cels: { low: FILE_A, high: FILE_B } }];
    const read = (file: string) => (file === FILE_A ? cel(1, 1, [[1]]) : cel(1, 1, [[2]]));
    expect([...composeFrame(asset, colors, asset.frames[0]!, read)!]).toEqual([128, 0, 128, 255]);
    asset.layers[1]!.hidden = true;
    expect([...composeFrame(asset, colors, asset.frames[0]!, read)!]).toEqual([255, 0, 0, 255]);
  });

  it('is transparent where nothing paints, and waits while a cel is loading', () => {
    const { project } = makeProject();
    const asset = art(project);
    asset.width = 1;
    asset.height = 1;
    const layer = asset.layers[0]!.id;
    asset.frames[0]!.cels[layer] = FILE_A;
    expect([...composeFrame(asset, colors, asset.frames[0]!, () => cel(1, 1, [[0]]))!]).toEqual([0, 0, 0, 0]);
    // An index past the palette's end is transparent too.
    expect([...composeFrame(asset, colors, asset.frames[0]!, () => cel(1, 1, [[9]]))!]).toEqual([0, 0, 0, 0]);
    expect(composeFrame(asset, colors, asset.frames[0]!, () => undefined)).toBeNull();
  });

  it('puts the frames side by side into one sheet', () => {
    const { project } = makeProject();
    const asset = art(project);
    asset.width = 1;
    asset.height = 1;
    const layer = asset.layers[0]!.id;
    asset.frames = [
      { id: 'f1', cels: { [layer]: FILE_A } },
      { id: 'f2', cels: { [layer]: FILE_B } },
    ];
    const sheet = composeSheet(asset, colors, (file) =>
      file === FILE_A ? cel(1, 1, [[1]]) : cel(1, 1, [[2]]),
    );
    expect([...sheet!]).toEqual([255, 0, 0, 255, 0, 0, 255, 255]);
  });

  it('reads colours by index, 0 being transparent', () => {
    expect(colorAt(colors, 0)).toBeNull();
    expect(colorAt(colors, 2)).toBe(0x0000ff);
    expect(colorAt(colors, 3)).toBeNull();
  });
});

describe('the picture', () => {
  it('changes its revision with the pixels, the palette and the layers, not with a name', () => {
    const { project } = makeProject();
    const asset = art(project);
    const layer = asset.layers[0]!.id;
    const before = pixelArtRevision(asset, DEFAULT_PALETTE);
    asset.layers[0]!.name = 'Renamed';
    expect(pixelArtRevision(asset, DEFAULT_PALETTE)).toBe(before);
    asset.frames[0]!.cels[layer] = FILE_A;
    const painted = pixelArtRevision(asset, DEFAULT_PALETTE);
    expect(painted).not.toBe(before);
    expect(pixelArtRevision(asset, [0x123456])).not.toBe(painted);
    asset.layers[0]!.opacity = 0.5;
    expect(pixelArtRevision(asset, DEFAULT_PALETTE)).not.toBe(painted);
  });

  it('is a sheet of all frames, and a frame id reads as a cut of it', () => {
    const remove = registerPictureSource('pixelart', pixelArtPicture);
    try {
      const { project } = makeProject();
      const asset = art(project);
      asset.width = 16;
      asset.height = 8;
      asset.frames.push({ id: 'second', cels: {} });
      const whole = resolvePicture(project, asset.id);
      expect(whole).toMatchObject({ rect: null, sourceWidth: 32, sourceHeight: 8, smooth: false });
      expect(whole!.file.startsWith(`gen:${asset.id}@`)).toBe(true);
      const second = resolvePicture(project, 'second');
      expect(second).toMatchObject({ file: whole!.file, rect: { x: 16, y: 0, w: 16, h: 8 } });
      expect(findPixelFrame(project, 'second')?.index).toBe(1);
      expect(textureRefLabel(project, 'second')).toBe('Art / Frame 2');
      expect(pictureChoices(project).map((c) => c.label)).toEqual(['Art', 'Art / Frame 1', 'Art / Frame 2']);
      expect(pixelArtWornId(asset)).toBe(asset.frames[0]!.id);
    } finally {
      remove();
    }
  });

  it('with one frame is offered as the picture alone', () => {
    const remove = registerPictureSource('pixelart', pixelArtPicture);
    try {
      const { project } = makeProject();
      const asset = art(project);
      expect(pictureChoices(project).map((c) => c.label)).toEqual(['Art']);
      expect(pixelArtWornId(asset)).toBe(asset.id);
    } finally {
      remove();
    }
  });

  it('is painted in the palette its row names, else in the default colours', () => {
    const { project } = makeProject();
    const asset = art(project);
    expect(paletteColors(project, asset)).toBe(DEFAULT_PALETTE);
    const palette = new CreateAssetCommand('palette', 'Palette');
    palette.execute(project);
    (palette.asset as PaletteAsset).colors = [0x112233];
    asset.props[PALETTE_KEY] = palette.asset.id;
    expect(paletteColors(project, asset)).toEqual([0x112233]);
  });
});

describe('edits', () => {
  const start = () => {
    const { project, stack } = makeProject();
    const asset = art(project);
    return { project, stack, asset, layer: asset.layers[0]!.id, frame: asset.frames[0]!.id };
  };

  it('sets cels and empties one with the empty name', () => {
    const { asset, layer, frame } = start();
    const painted = withCels(pixelArtState(asset), [{ frameId: frame, layerId: layer, file: FILE_A }]);
    expect(painted.frames[0]!.cels[layer]).toBe(FILE_A);
    expect(withCels(painted, [{ frameId: frame, layerId: layer, file: '' }]).frames[0]!.cels).toEqual({});
    // The state it was given is left alone.
    expect(asset.frames[0]!.cels).toEqual({});
  });

  it('adds, renames, hides, moves and removes layers, and keeps the last one', () => {
    const { asset, layer } = start();
    let s = withLayerAdded(pixelArtState(asset), 'second');
    expect(s.layers.map((l) => [l.id, l.name])).toEqual([
      [layer, 'Layer 1'],
      ['second', 'Layer 2'],
    ]);
    s = withLayerChanged(s, 'second', { name: ' Ink ', hidden: true, opacity: 3 });
    expect(s.layers[1]).toEqual({ id: 'second', name: 'Ink', hidden: true, opacity: 1 });
    expect(withLayerChanged(s, 'second', { hidden: false }).layers[1]).not.toHaveProperty('hidden');
    s = withLayerMoved(s, 'second', 0);
    expect(s.layers[0]!.id).toBe('second');
    s = withLayerRemoved(s, 'second');
    expect(() => withLayerRemoved(s, layer)).toThrow('at least one layer');
    expect(() => withLayerChanged(s, layer, { name: '  ' })).toThrow('needs a name');
  });

  it('merges a layer down into the cels it is handed', () => {
    const { asset, layer, frame } = start();
    let s = withLayerAdded(pixelArtState(asset), 'top');
    s = withCels(s, [{ frameId: frame, layerId: 'top', file: FILE_B }]);
    s = withLayerMergedDown(s, 'top', { [frame]: FILE_A });
    expect(s.layers.map((l) => l.id)).toEqual([layer]);
    expect(s.frames[0]!.cels).toEqual({ [layer]: FILE_A });
    expect(() => withLayerMergedDown(s, layer, {})).toThrow('no layer below');
  });

  it('adds a frame empty or as a copy, moves it and keeps the last one', () => {
    const { asset, layer, frame } = start();
    let s = withCels(pixelArtState(asset), [{ frameId: frame, layerId: layer, file: FILE_A }]);
    s = withFrameAdded(s, 'copy', frame, frame);
    s = withFrameAdded(s, 'blank', frame);
    expect(s.frames.map((f) => [f.id, f.cels[layer] ?? ''])).toEqual([
      [frame, FILE_A],
      ['blank', ''],
      ['copy', FILE_A],
    ]);
    s = withFrameMoved(s, 'copy', 0);
    expect(s.frames[0]!.id).toBe('copy');
    s = withFrameRemoved(withFrameRemoved(s, 'copy'), 'blank');
    expect(() => withFrameRemoved(s, frame)).toThrow('at least one frame');
  });

  it('resizes by swapping every cel for its counterpart', () => {
    const { asset, layer, frame } = start();
    const s = withCels(pixelArtState(asset), [{ frameId: frame, layerId: layer, file: FILE_A }]);
    const resized = withCanvasSize(s, 40, 16, { [FILE_A]: FILE_B });
    expect(resized).toMatchObject({ width: 40, height: 16 });
    expect(resized.frames[0]!.cels[layer]).toBe(FILE_B);
    expect(() => withCanvasSize(s, 40, 16, {})).toThrow('no counterpart');
    expect(() => withCanvasSize(s, 513, 16, { [FILE_A]: FILE_B })).toThrow('1 to 512');
  });

  it('is one undo step per command, and a refused edit changes nothing', () => {
    const { project, stack, asset, layer, frame } = start();
    stack.execute(
      new EditPixelArtCommand(asset.id, 'Pencil', (s) =>
        withCels(s, [{ frameId: frame, layerId: layer, file: FILE_A }]),
      ),
    );
    stack.execute(new EditPixelArtCommand(asset.id, 'Add layer', (s) => withLayerAdded(s, 'top')));
    const current = findAsset(project, asset.id) as PixelArtAsset;
    expect(current.layers).toHaveLength(2);
    stack.undo();
    expect(current.layers).toHaveLength(1);
    stack.undo();
    expect(current.frames[0]!.cels).toEqual({});
    stack.redo();
    expect(current.frames[0]!.cels[layer]).toBe(FILE_A);
    const refused = new EditPixelArtCommand(asset.id, 'Delete layer', (s) => withLayerRemoved(s, layer));
    expect(() => refused.execute(project)).toThrow(CommandError);
    expect(current.layers).toHaveLength(1);
  });

  it('sets the colours of a palette and takes them back', () => {
    const { project, stack } = makeProject();
    const create = new CreateAssetCommand('palette', 'Palette');
    stack.execute(create);
    const palette = create.asset as PaletteAsset;
    expect(palette.colors).toEqual(DEFAULT_PALETTE);
    stack.execute(new SetPaletteColorsCommand(palette.id, 'Palette colour', [0x010203]));
    expect(palette.colors).toEqual([0x010203]);
    stack.undo();
    expect(palette.colors).toEqual(DEFAULT_PALETTE);
    expect(() => new SetPaletteColorsCommand(palette.id, 'x', [0x1000000]).execute(project)).toThrow(
      CommandError,
    );
  });
});

describe('the project file', () => {
  it('brings pixel art and palettes back as they were', () => {
    const { project } = makeProject();
    const asset = art(project);
    const layer = asset.layers[0]!.id;
    asset.width = 48;
    asset.layers.push({ id: 'ink', name: 'Ink', opacity: 0.25, hidden: true });
    asset.frames[0]!.cels = { [layer]: FILE_A, ink: FILE_B };
    asset.frames.push({ id: 'second', cels: {} });
    const palette = new CreateAssetCommand('palette', 'Palette');
    palette.execute(project);
    const loaded = roundTrip(project);
    expect(findAsset(loaded, asset.id)).toEqual(asset);
    expect(findAsset(loaded, palette.asset.id)).toEqual(palette.asset);
  });

  it('drops what it cannot trust and keeps something to paint on', () => {
    const { project } = makeProject();
    const raw = JSON.parse(JSON.stringify(project)) as { assets: unknown[] };
    raw.assets.push(
      {
        id: 'bad',
        type: 'pixelart',
        name: 'Bad',
        props: {},
        width: 9999,
        height: 'x',
        layers: [{ id: 'l', name: 'L', opacity: 7 }, { id: 'l' }, { name: 'no id' }],
        frames: [
          { id: 'f', cels: { l: FILE_A, gone: FILE_B, l2: 'not-a-file' } },
          { id: 'f' },
          { id: 'bad' },
        ],
      },
      { id: 'empty', type: 'pixelart', name: 'Empty', props: {} },
      { id: 'pal', type: 'palette', name: 'Pal', props: {}, colors: [1, 'x', 0x1ffffff, 2.7] },
    );
    const loaded = roundTrip(raw as unknown as Project);
    const bad = findAsset(loaded, 'bad') as PixelArtAsset;
    expect(bad).toMatchObject({ width: 512, height: 32 });
    expect(bad.layers).toEqual([{ id: 'l', name: 'L', opacity: 1 }]);
    // A frame may not reuse its own asset's id, nor another frame's.
    expect(bad.frames).toEqual([{ id: 'f', cels: { l: FILE_A } }]);
    const empty = findAsset(loaded, 'empty') as PixelArtAsset;
    expect(empty.layers).toHaveLength(1);
    expect(empty.frames).toHaveLength(1);
    expect((findAsset(loaded, 'pal') as PaletteAsset).colors).toEqual([1, 0xffffff, 2]);
    expect(celFilesOf(bad)).toEqual([FILE_A]);
  });
});

describe('cels in the browser', () => {
  it('names painted pixels at once, keeps them, and uploads what the project names', async () => {
    const cels = new PixelCels();
    const pixels = cel(2, 1, [[1, 0]]);
    const file = cels.put(pixels);
    expect(file).toBe(celFileName(encodeCel(pixels)));
    expect(cels.put(emptyCel(2, 1))).toBe('');
    // A copy is kept: painting on on the array handed in changes nothing stored.
    pixels.data[0] = 9;
    expect([...cels.read(file)!.data]).toEqual([1, 0]);

    const { project } = makeProject();
    const asset = art(project);
    const unnamed = cels.put(cel(1, 1, [[3]]));
    asset.frames[0]!.cels[asset.layers[0]!.id] = file;
    expect(cels.pending(project)).toEqual([file]);

    const sent: string[] = [];
    await cels.upload(project, {
      upload: (bytes) => {
        const name = celFileName(new Uint8Array(bytes));
        sent.push(name);
        return Promise.resolve({ file: name });
      },
    });
    expect(sent).toEqual([file]);
    expect(cels.pending(project)).toEqual([]);
    expect(unnamed).not.toBe(file);
  });

  it('fails the upload when the server names the bytes differently', async () => {
    const cels = new PixelCels();
    const { project } = makeProject();
    const asset = art(project);
    asset.frames[0]!.cels[asset.layers[0]!.id] = cels.put(cel(1, 1, [[1]]));
    await expect(cels.upload(project, { upload: () => Promise.resolve({ file: FILE_A }) })).rejects.toThrow(
      'The server stored pixels as',
    );
    expect(cels.pending(project)).toHaveLength(1);
  });
});

describe('saving', () => {
  const inner = (log: string[]): ProjectStore => ({
    list: () => Promise.resolve([]),
    load: () => Promise.reject(new Error('unused')),
    save: () => {
      log.push('save');
      return Promise.resolve(2);
    },
    create: () => Promise.reject(new Error('unused')),
    delete: () => Promise.resolve(),
  });

  it('uploads the painted cels before the project that names them', async () => {
    const log: string[] = [];
    const cels = new PixelCels();
    const { project } = makeProject();
    const asset = art(project);
    asset.frames[0]!.cels[asset.layers[0]!.id] = cels.put(cel(1, 1, [[1]]));
    const store = new CelUploadStore(inner(log), cels, {
      upload: (bytes) => {
        log.push('upload');
        return Promise.resolve({ file: celFileName(new Uint8Array(bytes)) });
      },
    });
    expect(await store.save(project, 1)).toBe(2);
    expect(log).toEqual(['upload', 'save']);
  });

  it('does not save a project whose cels could not be uploaded', async () => {
    const log: string[] = [];
    const cels = new PixelCels();
    const { project } = makeProject();
    const asset = art(project);
    asset.frames[0]!.cels[asset.layers[0]!.id] = cels.put(cel(1, 1, [[1]]));
    const store = new CelUploadStore(inner(log), cels, {
      upload: () => Promise.reject(new Error('offline')),
    });
    await expect(store.save(project, 1)).rejects.toThrow('offline');
    expect(log).toEqual([]);
  });
});

describe('the view', () => {
  it('zooms in whole steps and fits the largest one', () => {
    expect(fitZoom(32, 32, 500, 400)).toBe(8);
    expect(fitZoom(512, 512, 300, 300)).toBe(1);
    expect(stepZoom(8, 1)).toBe(12);
    expect(stepZoom(8, -1)).toBe(6);
    expect(stepZoom(32, 1)).toBe(32);
    expect(stepZoom(1, -1)).toBe(1);
  });

  it('finds the pixel under the pointer, outside the canvas too', () => {
    const view = { panX: 10, panY: 20, zoom: 8 };
    expect(pixelUnder(view, 10, 20)).toEqual({ x: 0, y: 0 });
    expect(pixelUnder(view, 17.9, 27.9)).toEqual({ x: 0, y: 0 });
    expect(pixelUnder(view, 9, 20)).toEqual({ x: -1, y: 0 });
  });
});