Measure reference logo placeholders and add slot-based logo placement

scripts/logo/measure-placeholders rasterises the reference PDFs and measures
each logo placeholder's ink box and density into slots.generated.ts. The
new placement contains the logo in the measured box, shrinks denser logos
by up to 30 percent to match visual weight, picks knockout or a white chip
on dark surfaces, and passes an identity test per template. A contact
sheet compares each placeholder with the Test Vendor logo and three test logos.

src/pdf/engine/logo.ts

@@ -1,3 +1,5 @@
+import type { Box, TemplateSlot } from "../templates/slots.types";
+
 export interface LogoPlacementInput {
   /** Width / height of the image (use the trimmed ink aspect once the logo pipeline provides it). */
   aspect: number;
@@ -24,15 +26,117 @@ export const LOGO_GAP = 14;
  * Fits the logo inside `box` by its aspect (contain), then decides whether it still leaves the text
  * `minTextWidth` beside it. Same maths as the Phase 0 planLogo.
  */
-export function computeLogoPlacement({ aspect, box, availableWidth, minTextWidth, gap = LOGO_GAP }: LogoPlacementInput): LogoPlacement {
+export function computeClassicLogoPlacement({ aspect, box, availableWidth, minTextWidth, gap = LOGO_GAP }: LogoPlacementInput): LogoPlacement {
   const a = Number.isFinite(aspect) && aspect > 0 ? aspect : box.w / box.h;
   const h = Math.min(box.h, box.w / a);
   const w = h * a;
   return { w, h, stacked: availableWidth - w - gap < minTextWidth };
 }
 
-/*
- * Seam for reference templates: slots.generated.ts (measured placeholder boxes, see
- * scripts/logo/measure-placeholders.mjs) will supply a template's `logo.box` and may refine the fit.
- * Until it exists, every template declares its box by hand in its TemplateDefinition.
+/** Smallest height a logo is drawn at when its box allows it, pt. */
+export const MIN_LOGO_HEIGHT = 14;
+/** White padding of the chip behind a logo that has no knockout variant, pt. */
+export const CHIP_PADDING = 4;
+/** The weight factor never shrinks a logo below this share of its contain-fit size. */
+const MIN_WEIGHT_FACTOR = 0.7;
+
+/** Ratio of the page's content width to the reference page's (1 for the page the slot was measured on). */
+export type PageScale = number;
+
+export interface SlotLogoInput {
+  /** Width / height of the logo's ink box. */
+  aspect: number;
+  /** Share of the ink box that is ink, 0 to 1. */
+  density: number;
+  kind: "wordmark" | "mark" | "tall";
+  /** The logo already carries the business name, so it replaces the template's whole lockup. */
+  includesName: boolean;
+  /** A white-ink variant exists, for dark surfaces. */
+  hasKnockout: boolean;
+}
+
+export interface SlotLogoPlacementInput {
+  logo: SlotLogoInput;
+  slot: TemplateSlot;
+  scale?: PageScale;
+  /** Room the layout can actually give the logo; the target box shrinks to it, keeping its anchor. */
+  available?: { w: number; h: number };
+}
+
+export interface SlotLogoPlacement {
+  /** Where the logo image goes, page points from the top-left. */
+  box: Box;
+  x: number;
+  y: number;
+  w: number;
+  h: number;
+  variant: "print" | "knockout" | "chip";
+  /** Which placeholder box the logo was fitted to. */
+  slotKind: "lockup" | "mark";
+  /** For the chip variant: the white rounded rectangle behind the logo (the logo box plus CHIP_PADDING). */
+  chip?: Box;
+  /** Only Classic's own stack-or-beside decision sets this; slot placement never stacks. */
+  stacked?: boolean;
+}
+
+const clamp = (v: number, lo: number, hi: number) => Math.min(hi, Math.max(lo, v));
+
+/** A w x h box inside `target`, aligned the way the placeholder was. */
+function align(target: Box, w: number, h: number, slot: TemplateSlot): Box {
+  const x = slot.anchor === "left" ? target.x : slot.anchor === "right" ? target.x + target.w - w : target.x + (target.w - w) / 2;
+  const y = slot.vAlign === "top" ? target.y : slot.vAlign === "bottom" ? target.y + target.h - h : target.y + (target.h - h) / 2;
+  return { x, y, w, h };
+}
+
+/**
+ * Places the user's logo where a template's logo placeholder is. Contain-fit in the measured box, then
+ * a shrink-only weight factor so a denser logo draws smaller and matches the placeholder's visual
+ * weight. A wordmark (includesName) replaces the whole lockup; a mark replaces the icon only. The
+ * legibility floor never pushes past the box: a box under MIN_LOGO_HEIGHT stays the limit.
  */
+export function computeLogoPlacement({ logo, slot, scale = 1, available }: SlotLogoPlacementInput): SlotLogoPlacement {
+  const wantLockup = logo.includesName || !slot.mark;
+  const target = wantLockup ? (slot.lockup ?? slot.mark) : slot.mark;
+  if (!target) throw new Error("slot has neither a mark nor a lockup box");
+  const slotKind = wantLockup ? "lockup" : "mark";
+  const placeholderDensity = wantLockup ? slot.lockupDensity : slot.markDensity;
+
+  // Scale the box about its anchor so a right-aligned slot keeps its right edge.
+  let bw = target.w * scale;
+  let bh = target.h * scale;
+  if (available) {
+    bw = Math.min(bw, available.w);
+    bh = Math.min(bh, available.h);
+  }
+  const box = align(target, bw, bh, slot);
+
+  const aspect = Number.isFinite(logo.aspect) && logo.aspect > 0 ? logo.aspect : bw / bh;
+  let h = Math.min(bh, bw / aspect);
+  let w = h * aspect;
+
+  const valid = logo.density > 0 && placeholderDensity > 0;
+  const f = valid ? clamp(Math.sqrt(placeholderDensity / logo.density), MIN_WEIGHT_FACTOR, 1) : 1;
+  w *= f;
+  h *= f;
+
+  if (h < MIN_LOGO_HEIGHT) {
+    h = MIN_LOGO_HEIGHT;
+    w = h * aspect;
+    if (w > bw) {
+      w = bw;
+      h = w / aspect;
+    }
+    if (h > bh) {
+      h = bh;
+      w = h * aspect;
+    }
+  }
+
+  const placed = align(box, w, h, slot);
+  const variant = slot.darkSurface ? (logo.hasKnockout ? "knockout" : "chip") : "print";
+  const out: SlotLogoPlacement = { box: placed, ...placed, variant, slotKind };
+  if (variant === "chip") {
+    out.chip = { x: placed.x - CHIP_PADDING, y: placed.y - CHIP_PADDING, w: placed.w + 2 * CHIP_PADDING, h: placed.h + 2 * CHIP_PADDING };
+  }
+  return out;
+}