MVP - Scale Pages, Scale Content

2023-10-16 23:11:33 +02:00
commit 542d74b9cc
10 changed files with 569 additions and 0 deletions
--- a/public/functions/scaleContent.js
+++ b/public/functions/scaleContent.js
@@ -0,0 +1,29 @@
+const { PDFDocument, ParseSpeeds } = PDFLib;
+
+export const scaleContent = async (snapshot, scale_factor) => {
+    // Load the original PDF file
+    const pdfDoc = await PDFDocument.load(snapshot, {
+        parseSpeed: ParseSpeeds.Fastest,
+    });
+
+    const pages = pdfDoc.getPages();
+
+    pages.forEach(page => {
+        const width = page.getWidth();
+        const height = page.getHeight();
+        
+        // Scale content
+        page.scaleContent(scale_factor, scale_factor);
+        const scaled_diff = {
+            width: Math.round(width - scale_factor * width),
+            height: Math.round(height - scale_factor * height),
+        };
+
+        // Center content in new page format
+        page.translateContent(Math.round(scaled_diff.width / 2), Math.round(scaled_diff.height / 2));
+
+    });
+
+    // Serialize the modified document
+    return pdfDoc.save();
+};
--- a/public/functions/scalePage.js
+++ b/public/functions/scalePage.js
@@ -0,0 +1,31 @@
+const { PDFDocument, ParseSpeeds } = PDFLib;
+
+export const scalePage = async (snapshot, page_size) => {
+    // Load the original PDF file
+    const pdfDoc = await PDFDocument.load(snapshot, {
+        parseSpeed: ParseSpeeds.Fastest,
+    });
+
+    const new_size = page_size;
+
+    const pages = pdfDoc.getPages();
+
+    pages.forEach(page => {
+        // Change page size
+        page.setSize(new_size.width, new_size.height);
+    });
+
+    // Serialize the modified document
+    return pdfDoc.save();
+};
+
+export const PageSize = {
+    a4: {
+        width: 594.96,
+        height: 841.92
+    },
+    letter: {
+        width: 612,
+        height: 792
+    }
+};
--- a/public/index.css
+++ b/public/index.css
--- a/public/index.html
+++ b/public/index.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+
+    <script src="https://unpkg.com/pdf-lib@1.17.1/dist/pdf-lib.min.js"></script>
+    <script src="https://unpkg.com/downloadjs@1.4.7"></script>
+
+    <script src="index.js" type="module"></script>
+</head>
+<body>
+    <input type="file" id="pdfFile" accept=".pdf">
+    <a id="downloadLink" style="display: none;" download="modified.pdf">Download Modified PDF</a>
+</body>
+</html>
--- a/public/index.js
+++ b/public/index.js
@@ -0,0 +1,16 @@
+import { scaleContent } from "./functions/scaleContent.js";
+import { scalePage, PageSize } from "./functions/scalePage.js";
+
+(async () => {
+    const pdfFileInput = document.getElementById('pdfFile');
+
+    pdfFileInput.addEventListener('change', async (e) => {
+        const file = e.target.files[0];
+        if (file) {
+            let pdfBuffer = new Uint8Array(await file.arrayBuffer());
+            pdfBuffer = await scaleContent(pdfBuffer, 2);
+            pdfBuffer = await scalePage(pdfBuffer, PageSize.letter);
+            download(pdfBuffer, "pdf-lib_creation_example.pdf", "application/pdf");
+        }
+    });
+})();