Centre the voucher letter whatever the bold font

.changeset/letter-centre.md

@@ -0,0 +1,6 @@
+---
+"facturas": patch
+"@facturas/pdf": patch
+---
+
+`@facturas/pdf` centra la letra del comprobante en su recuadro con cualquier fuente del tema. Con una altura de línea fija, una fuente de ascendente alto como Geist la bajaba 3,6 puntos.

packages/pdf/src/theme.ts

@@ -116,7 +116,9 @@ export function createStyles(theme: ResolvedTheme) {
       alignItems: "center",
       justifyContent: "center",
     },
-    letter: { ...bold, fontSize: 24, lineHeight: 1, color: theme.accentColor },
+    // No lineHeight: the font's own line box centres the capital in the box.
+    // A fixed one sinks it by the font's ascent, 3.6 pt with Geist.
+    letter: { ...bold, fontSize: 24, color: theme.accentColor },
     code: { fontSize: 7.5, color: theme.textColor },
     letterLegend: { ...bold, fontSize: 6.5, textAlign: "center" },
     issuerName: {

packages/pdf/src/voucher.test.tsx

@@ -164,6 +164,26 @@ describe("<Voucher>", () => {
     expect(hasText(page, "Régimen de Transparencia Fiscal")).toBe(false);
   });
 
+  it("centres the letter in its box whatever the bold font", async () => {
+    // The box starts below the page and column padding and its 0.6 pt outline.
+    const boxCentre = 32 + 14 + 0.6 + 20;
+    // Cap heights of the standard fonts, in thousandths of the size.
+    for (const [boldFontFamily, capHeight] of [
+      ["Helvetica-Bold", 718],
+      ["Times-Bold", 676],
+    ] as const) {
+      const [page] = await readPdf(
+        await renderVoucherPdf(classBDocument(), { theme: { boldFontFamily } })
+      );
+      if (page === undefined) {
+        throw new Error("no page");
+      }
+      const letter = findExact(page, "B");
+      const capCentre = letter.top - (letter.fontSize * capHeight) / 2000;
+      expect(Math.abs(capCentre - boxCentre)).toBeLessThan(0.5);
+    }
+  });
+
   it("drops the line rate column on class A when every line has the same rate", async () => {
     const doc = classADocument();
     const single = {