refactoring, numbering plan

tests/unit/pdf-text-overlay.spec.ts

@@ -0,0 +1,133 @@
+import { expect, test } from '@playwright/test';
+import { degrees, PDFDocument, StandardFonts, rgb } from 'pdf-lib';
+import { TextOverlayError } from '../../src/lib/pdf-errors';
+import {
+	TEXT_OVERLAY_MARGIN,
+	drawTextOverlay,
+	getRotatedBoxPlacement
+} from '../../src/lib/pdf-text-overlay';
+import { getPageText, getPageTextAngle, getPageTextMatrix } from '../e2e/helpers';
+
+const PAGE_WIDTH = 420;
+const PAGE_HEIGHT = 594;
+const MARGIN = 28;
+
+/**
+ * Maps a point from default user space to the displayed page. Viewers rotate the
+ * content clockwise by `/Rotate`, so this is the forward transformation.
+ */
+const toVisualPoint = (
+	point: { x: number; y: number },
+	rotation: number,
+	width: number,
+	height: number
+) => {
+	switch (rotation) {
+		case 90:
+			return { x: point.y, y: width - point.x };
+		case 180:
+			return { x: width - point.x, y: height - point.y };
+		case 270:
+			return { x: height - point.y, y: point.x };
+		default:
+			return point;
+	}
+};
+
+const createPageWithMark = async (rotation: number) => {
+	const document = await PDFDocument.create();
+	const font = await document.embedFont(StandardFonts.Helvetica);
+	const page = document.addPage([PAGE_WIDTH, PAGE_HEIGHT]);
+	page.setRotation(degrees(rotation));
+	drawTextOverlay(page, {
+		font,
+		text: 'Bl. 1',
+		size: 11,
+		color: rgb(0.1, 0.1, 0.1),
+		position: 'bottom-center',
+		margin: MARGIN,
+		compensatePageRotation: true
+	});
+
+	return PDFDocument.load(await document.save());
+};
+
+for (const rotation of [0, 90, 180, 270]) {
+	test(`bottom-center mark stays at the visual bottom on a /Rotate ${rotation} page`, async () => {
+		const output = await createPageWithMark(rotation);
+		const matrix = getPageTextMatrix(output, 0);
+		const visualWidth = rotation % 180 === 0 ? PAGE_WIDTH : PAGE_HEIGHT;
+		const origin = toVisualPoint({ x: matrix.x, y: matrix.y }, rotation, PAGE_WIDTH, PAGE_HEIGHT);
+
+		// Horizontally centred on the displayed page.
+		expect(Math.abs(origin.x - visualWidth / 2)).toBeLessThan(30);
+		// Close to the bottom margin (the baseline sits a few points above it).
+		expect(origin.y).toBeGreaterThan(MARGIN - 2);
+		expect(origin.y).toBeLessThan(MARGIN + 20);
+		// The glyphs read horizontally: the drawn angle cancels the page rotation.
+		expect(Math.round(getPageTextAngle(matrix))).toBe(rotation);
+		expect(getPageText(output, 0)).toBe('Bl. 1');
+	});
+}
+
+test('a mark that does not fit raises a TextOverlayError instead of shrinking forever', async () => {
+	const document = await PDFDocument.create();
+	const font = await document.embedFont(StandardFonts.Helvetica);
+	const page = document.addPage([120, 160]);
+
+	expect(() =>
+		drawTextOverlay(page, {
+			font,
+			text: 'Ein sehr langer Stempeltext, der nicht auf die Seite passt',
+			size: 18,
+			color: rgb(0, 0, 0),
+			position: 'bottom-center',
+			margin: MARGIN,
+			framed: true
+		})
+	).toThrow(TextOverlayError);
+});
+
+test('characters the standard font cannot encode are reported as such', async () => {
+	const document = await PDFDocument.create();
+	const font = await document.embedFont(StandardFonts.Helvetica);
+	const page = document.addPage([PAGE_WIDTH, PAGE_HEIGHT]);
+
+	let thrown: unknown;
+	try {
+		drawTextOverlay(page, {
+			font,
+			text: 'Beschluss \u{1F600}',
+			size: 11,
+			color: rgb(0, 0, 0),
+			position: 'top-right',
+			margin: MARGIN
+		});
+	} catch (error) {
+		thrown = error;
+	}
+
+	expect(thrown).toBeInstanceOf(TextOverlayError);
+	expect((thrown as Error).message).toContain('nicht dargestellt werden');
+});
+
+test('a rotated mark keeps its bounding box inside the page', async () => {
+	const boxWidth = 200;
+	const boxHeight = 40;
+
+	for (const angle of [0, 45, 90, 135]) {
+		const placement = getRotatedBoxPlacement(
+			PAGE_WIDTH,
+			PAGE_HEIGHT,
+			boxWidth,
+			boxHeight,
+			'bottom-center',
+			angle,
+			TEXT_OVERLAY_MARGIN
+		);
+
+		expect(placement.x).toBeGreaterThanOrEqual(TEXT_OVERLAY_MARGIN - 0.001);
+		expect(placement.y).toBeGreaterThanOrEqual(TEXT_OVERLAY_MARGIN - 0.001);
+		expect(placement).not.toHaveProperty('cosine');
+	}
+});