feat: finish the homepage plugin, move service links and canvas out of core (B19)

plugins/homepage/tests/frontend/canvas/canvasGeometry.test.ts

@@ -0,0 +1,80 @@
+import { describe, it, expect } from "vitest";
+import {
+  screenToCanvas,
+  canvasToScreen,
+  zoomAroundPoint,
+} from "../../../src/frontend/canvas/canvasGeometry.js";
+
+const PAN = { x: 100, y: 200 };
+const ZOOM = 2;
+
+describe("screenToCanvas", () => {
+  it("inverts canvasToScreen", () => {
+    const canvas = { x: 50, y: 75 };
+    const screen = canvasToScreen(canvas.x, canvas.y, PAN, ZOOM);
+    const back = screenToCanvas(screen.x, screen.y, PAN, ZOOM);
+    expect(back.x).toBeCloseTo(canvas.x);
+    expect(back.y).toBeCloseTo(canvas.y);
+  });
+
+  it("accounts for pan offset", () => {
+    const result = screenToCanvas(100, 200, PAN, 1);
+    expect(result.x).toBe(0);
+    expect(result.y).toBe(0);
+  });
+
+  it("accounts for zoom", () => {
+    const result = screenToCanvas(300, 400, PAN, ZOOM);
+    expect(result.x).toBe((300 - 100) / 2);
+    expect(result.y).toBe((400 - 200) / 2);
+  });
+});
+
+describe("canvasToScreen", () => {
+  it("maps origin with pan offset", () => {
+    const result = canvasToScreen(0, 0, PAN, ZOOM);
+    expect(result.x).toBe(100);
+    expect(result.y).toBe(200);
+  });
+
+  it("scales by zoom", () => {
+    const result = canvasToScreen(10, 20, PAN, ZOOM);
+    expect(result.x).toBe(120);
+    expect(result.y).toBe(240);
+  });
+});
+
+describe("zoomAroundPoint", () => {
+  it("keeps the mouse point on the same canvas coordinate", () => {
+    const mouseX = 400;
+    const mouseY = 300;
+    const pan = { x: 0, y: 0 };
+    const oldZoom = 1;
+    const newZoom = 2;
+
+    const newPan = zoomAroundPoint(mouseX, mouseY, pan, oldZoom, newZoom);
+
+    // Canvas coordinate under mouse before zoom
+    const canvasBefore = screenToCanvas(mouseX, mouseY, pan, oldZoom);
+    // Canvas coordinate under mouse after zoom with newPan
+    const canvasAfter = screenToCanvas(mouseX, mouseY, newPan, newZoom);
+
+    expect(canvasAfter.x).toBeCloseTo(canvasBefore.x);
+    expect(canvasAfter.y).toBeCloseTo(canvasBefore.y);
+  });
+
+  it("returns correct pan for zoom-out", () => {
+    const mouseX = 200;
+    const mouseY = 150;
+    const pan = { x: 50, y: 50 };
+    const oldZoom = 2;
+    const newZoom = 1;
+
+    const newPan = zoomAroundPoint(mouseX, mouseY, pan, oldZoom, newZoom);
+    const canvasBefore = screenToCanvas(mouseX, mouseY, pan, oldZoom);
+    const canvasAfter = screenToCanvas(mouseX, mouseY, newPan, newZoom);
+
+    expect(canvasAfter.x).toBeCloseTo(canvasBefore.x);
+    expect(canvasAfter.y).toBeCloseTo(canvasBefore.y);
+  });
+});

plugins/homepage/tests/frontend/canvas/snapToGrid.test.ts

@@ -0,0 +1,42 @@
+import { describe, it, expect } from "vitest";
+import {
+  snapToGrid,
+  snapToGridFloor,
+} from "../../../src/frontend/canvas/snapToGrid.js";
+import { GRID_SIZE } from "../../../src/frontend/types.js";
+
+describe("snapToGrid", () => {
+  it("snaps to nearest grid multiple", () => {
+    expect(snapToGrid(0)).toBe(0);
+    expect(snapToGrid(GRID_SIZE)).toBe(GRID_SIZE);
+    expect(snapToGrid(GRID_SIZE * 2)).toBe(GRID_SIZE * 2);
+  });
+
+  it("rounds to nearest (up when exactly halfway)", () => {
+    expect(snapToGrid(GRID_SIZE / 2)).toBe(GRID_SIZE);
+    expect(snapToGrid(GRID_SIZE * 1.5)).toBe(GRID_SIZE * 2);
+  });
+
+  it("rounds down when below halfway", () => {
+    expect(snapToGrid(GRID_SIZE * 0.4)).toBe(0);
+    expect(snapToGrid(GRID_SIZE * 1.4)).toBe(GRID_SIZE);
+  });
+
+  it("works with negative values", () => {
+    expect(snapToGrid(-GRID_SIZE)).toBe(-GRID_SIZE);
+    expect(snapToGrid(-GRID_SIZE * 0.4)).toBeCloseTo(0);
+  });
+});
+
+describe("snapToGridFloor", () => {
+  it("always rounds down to floor multiple", () => {
+    expect(snapToGridFloor(GRID_SIZE - 1)).toBe(0);
+    expect(snapToGridFloor(GRID_SIZE)).toBe(GRID_SIZE);
+    expect(snapToGridFloor(GRID_SIZE + 1)).toBe(GRID_SIZE);
+    expect(snapToGridFloor(GRID_SIZE * 2 - 1)).toBe(GRID_SIZE);
+  });
+
+  it("handles zero", () => {
+    expect(snapToGridFloor(0)).toBe(0);
+  });
+});