Vector shapes can be combined by union, subtract and more (#187)

Building a shape out of simpler ones meant drawing the result point by
point. The Vector Art tab now selects several shapes at once and
combines them with a boolean operation into one ordinary shape.

- Ctrl/Cmd+click in the tab and Ctrl or Shift+click in the shape list
  add a shape to the selection. Shift stays pan in the canvas.
- A COMBINE block in the inspector offers Union, Subtract, Intersect
  and Exclude. Subtract removes every upper shape from the lowest one.
- The result replaces the lowest selected shape and keeps its name,
  colours, stroke and place in the order. It is one undo step.
- Curves are flattened to 0.2 canvas pixels, a circle gets about 48
  points. Open lines and single shapes cannot be combined, the buttons
  are off and a hint gives the reason. An empty result is rejected.
- Delete now removes every selected shape, and the selection drops
  shapes that no longer exist.
- The geometry comes from clipper2-ts 2.0.1, pinned. It has no
  dependencies and speaks even-odd directly. Only the engine module
  is imported, the bundle grows by 55 kB instead of 110 kB.

Findings:

- clipper2-js was tried and dropped. It pulls in Angular 15 with a
  high npm audit finding and no fix.
- Pixi finds holes by containment, not by even-odd depth. An island
  inside a hole would be drawn as a hole again. Result rings are
  emitted outer ring before its islands, and a test mirrors Pixi's
  rule.
- A depth sort turned out to be dead code in a counter-check and was
  removed. A pixel check in 47h stayed green without the subtract
  and now checks both colours.

Tests:

- ./check.sh: 134 files, 1986 tests, exit 0 (before 133 / 1968)
- npm run build: exit 0
- GM_STEPS=47, freshly seeded: ALL PASSED, 44 checks (before 39)
- 18 new unit tests, 5 new e2e checks in block 47h
- Five counter-checks bite, originals restored and verified with cmp
- Check sum 1222 in README and wiki, calculated (1217 + 5)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/editor/shape-rows.test.ts

@@ -5,11 +5,12 @@
  */
 import { beforeAll, describe, expect, it } from 'vitest';
 import { CanvasTextMetrics } from 'pixi.js';
-import { AddVectorShapeCommand } from '../../src/core/commands/vectorArtCommands';
+import { AddVectorShapeCommand, RemoveVectorShapeCommand } from '../../src/core/commands/vectorArtCommands';
 import type { VectorArtAsset } from '../../src/core/model/Asset';
 import { buildAsset } from '../../src/core/commands/assetCommands';
 import { createEmptyProject, findAssetOf } from '../../src/core/model/Project';
 import {
+  Button,
   Checkbox,
   ColorField,
   Label,
@@ -27,7 +28,7 @@ import {
   shapeSignature,
 } from '../../src/editor/inspector/shapeSection';
 import { shapeDropGap, shapeDropMove, shapeRowOrder } from '../../src/editor/vectorart/shapeRows';
-import { EditorState } from '../../src/editor/state';
+import { EditorState, shapeSelection } from '../../src/editor/state';
 
 const ROW = 30;
 
@@ -124,14 +125,14 @@ describe('shape list order', () => {
 describe('shape rows', () => {
   it('shows fill, opacity and an outline switch, and no line rows without an outline', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     expect([...host.fields.keys()]).toEqual(['name', 'fill', 'opacity', 'outline']);
     expect(texts(host)).toContain('Without an outline only the fill is drawn.');
   });
 
   it('writes a fill as one undo step, a dragged colour previewing without one', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     const before = shapeOf(host, assetId).fill;
     const fill = widgets(host, ColorField)[0]!;
     fill.onInput!(0xff0000);
@@ -144,7 +145,7 @@ describe('shape rows', () => {
 
   it('writes the opacity, clamped to what an opacity can be', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     // A NumberField reads text: its own `onChange` is the one a typed value goes through.
     const opacity = widgets(host, NumberField)[0]!;
     opacity.onChange!('0.4');
@@ -155,7 +156,7 @@ describe('shape rows', () => {
 
   it('the outline switch adds a line and takes it away again', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     widgets(host, Checkbox)[0]!.toggle();
     expect(shapeOf(host, assetId).stroke).toEqual({ color: 0x000000, width: 2 });
     host.state.undo();
@@ -165,7 +166,7 @@ describe('shape rows', () => {
   it('shows the line rows once there is a line, and a width of nothing is not one', () => {
     const { host, assetId, ids } = withShapes(1);
     shapeOf(host, assetId).stroke = { color: 0x112233, width: 3 };
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     expect([...host.fields.keys()]).toEqual([
       'name',
       'fill',
@@ -184,25 +185,25 @@ describe('shape rows', () => {
 
   it('names the shapes and the outline in its signature, so both rebuild the rows', () => {
     const { host, assetId, ids } = withShapes(2);
-    const before = shapeSignature(host.state.project, assetId, ids[0]!);
+    const before = shapeSignature(host.state.project, assetId, ids[0]!, [ids[0]!]);
     shapeOf(host, assetId).name = 'Hat';
-    const renamed = shapeSignature(host.state.project, assetId, ids[0]!);
+    const renamed = shapeSignature(host.state.project, assetId, ids[0]!, [ids[0]!]);
     expect(renamed).not.toBe(before);
     shapeOf(host, assetId).stroke = { color: 0, width: 1 };
-    expect(shapeSignature(host.state.project, assetId, ids[0]!)).not.toBe(renamed);
+    expect(shapeSignature(host.state.project, assetId, ids[0]!, [ids[0]!])).not.toBe(renamed);
   });
 
   it('a shape that is gone asks for a rebuild instead of refreshing', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     expect(refreshShapeSection(host, assetId, ids[0]!)).toBe(true);
     expect(refreshShapeSection(host, assetId, 'gone')).toBe(false);
-    expect(shapeSignature(host.state.project, assetId, 'gone')).toBe('missing');
+    expect(shapeSignature(host.state.project, assetId, 'gone', ['gone'])).toBe('missing');
   });
 
   it('refreshing pushes the model values back into the rows', () => {
     const { host, assetId, ids } = withShapes(1);
-    buildShapeSection(host, assetId, ids[0]!);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
     const shape = shapeOf(host, assetId);
     shape.fill = 0x123456;
     shape.name = 'Cloud';
@@ -226,3 +227,57 @@ describe('shape rows', () => {
     expect(texts(host).some((t) => t.startsWith('Nothing drawn yet'))).toBe(true);
   });
 });
+
+describe('combining from the inspector (#187)', () => {
+  const button = (host: InspectorHost, text: string) => widgets(host, Button).find((b) => b.text === text)!;
+
+  it('Ctrl+click adds a shape and takes it out again; emptied, the drawing stays selected', () => {
+    const { host, assetId, ids } = withShapes(2);
+    host.state.select(shapeSelection(assetId, [ids[0]!]));
+    host.state.toggleShape(assetId, ids[1]!);
+    expect(host.state.selection).toMatchObject({ shapeId: ids[1], shapeIds: [ids[0], ids[1]] });
+    host.state.toggleShape(assetId, ids[1]!);
+    host.state.toggleShape(assetId, ids[0]!);
+    expect(host.state.selection).toEqual({ kind: 'asset', assetId });
+  });
+
+  it('switches the four buttons off for one shape and says how to get a second', () => {
+    const { host, assetId, ids } = withShapes(2);
+    buildShapeSection(host, assetId, ids[0]!, [ids[0]!]);
+    expect(['Union', 'Subtract', 'Intersect', 'Exclude'].map((t) => button(host, t).eventMode)).toEqual([
+      'none',
+      'none',
+      'none',
+      'none',
+    ]);
+    expect(texts(host)).toContain('Ctrl+click a second shape to combine.');
+  });
+
+  it('combines the selected shapes into the lowest one and selects it', () => {
+    const { host, assetId, ids } = withShapes(3);
+    host.state.select(shapeSelection(assetId, [ids[2]!, ids[1]!]));
+    buildShapeSection(host, assetId, ids[1]!, [ids[2]!, ids[1]!]);
+    expect(texts(host)).toContain('The result keeps "Shape 2", the lowest.');
+    button(host, 'Union').onClick!();
+    expect(findAssetOf(host.state.project, assetId, 'vectorart')!.shapes.map((s) => s.id)).toEqual([
+      ids[0],
+      ids[1],
+    ]);
+    expect(host.state.selection).toMatchObject({ shapeId: ids[1], shapeIds: [ids[1]] });
+  });
+
+  it('drops a selected shape that is gone and keeps the rest', () => {
+    const { host, assetId, ids } = withShapes(3);
+    host.state.select(shapeSelection(assetId, [ids[0]!, ids[2]!]));
+    host.state.execute(new RemoveVectorShapeCommand(assetId, ids[2]!));
+    expect(host.state.selection).toMatchObject({ shapeId: ids[0], shapeIds: [ids[0]] });
+  });
+
+  it('names the selected shapes in the signature, so a Ctrl+click rebuilds the rows', () => {
+    const { host, assetId, ids } = withShapes(2);
+    const project = host.state.project;
+    expect(shapeSignature(project, assetId, ids[0]!, [ids[0]!])).not.toBe(
+      shapeSignature(project, assetId, ids[0]!, [ids[1]!, ids[0]!]),
+    );
+  });
+});