From f24e611c4e00f8effdf7b83febd9860ac0915c1c Mon Sep 17 00:00:00 2001
From: Huang Xin <chrox.huang@gmail.com>
Date: Fri, 18 Oct 2024 12:05:31 +0800
Subject: [PATCH] Lazy loading of PDF documents (#37) (#38)

---
 pdf.js | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/pdf.js b/pdf.js
index fc224f9..dbde8d9 100644
--- a/pdf.js
+++ b/pdf.js
@@ -105,9 +105,14 @@ const makeTOCItem = item => ({
 })
 
 export const makePDF = async file => {
-    const data = new Uint8Array(await file.arrayBuffer())
+    const transport = new pdfjsLib.PDFDataRangeTransport(file.size, [])
+    transport.requestDataRange = (begin, end) => {
+        file.slice(begin, end).arrayBuffer().then(chunk => {
+            transport.onDataRange(begin, chunk)
+        })
+    }
     const pdf = await pdfjsLib.getDocument({
-        data,
+        range: transport,
         cMapUrl: pdfjsPath('cmaps/'),
         standardFontDataUrl: pdfjsPath('standard_fonts/'),
         isEvalSupported: false,