From 27d6f6c11685ee2377ab2af15fb3a5e835240f70 Mon Sep 17 00:00:00 2001
From: Erik Demaine <edemaine@mit.edu>
Date: Thu, 21 Dec 2023 17:06:44 -0500
Subject: [PATCH] Render selectable PDF text and upgrade pdfjs to v3

---
 CHANGELOG.md             |  4 ++++
 client/MessagePDF.coffee | 12 +++++++-----
 client/message.styl      | 13 ++++++++++---
 package.json             |  4 ++--
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2f78613..a9d6493 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ To see every change with descriptions aimed at developers, see
 As a continuously updated web app, Coauthor uses dates
 instead of version numbers.
 
+## 2023-12-21
+
+* You can now select and copy text from PDFs.
+
 ## 2023-12-20
 
 * Fix the wrong page's PDF links sometimes showing up when quickly flipping
diff --git a/client/MessagePDF.coffee b/client/MessagePDF.coffee
index ab1d9a5..7782c88 100644
--- a/client/MessagePDF.coffee
+++ b/client/MessagePDF.coffee
@@ -131,13 +131,14 @@ WrappedMessagePDF = React.memo ({file}) ->
     canvas.height = height * dpiScale
     #unless dpiScale == 1
     canvas.style.transform = "scale(#{1/dpiScale},#{1/dpiScale})"
-    canvas.style.transformOrigin = "0% 0%"
-    scaledViewport = page.getViewport scale: dpiScale * width / viewport.width
+    scale = dpiScale * width / viewport.width
+    scaledViewport = page.getViewport {scale}
     setRendering true
     renderTask = page.render
       canvasContext: context
       viewport: scaledViewport
     canceled = false
+    textRender = null
     Promise.all [renderTask.promise, page.getAnnotations()]
     .then ([rendered, annotationsLoaded]) =>
       return if canceled
@@ -162,10 +163,10 @@ WrappedMessagePDF = React.memo ({file}) ->
       setRendering false
       setAnnotations newAnnotations
       setAnnotationsTransform "scale(#{1/dpiScale},#{1/dpiScale}) matrix(#{scaledViewport.transform.join ','})"
+      textRef.current.style.setProperty '--scale-factor', scale
       textRef.current.style.transform = "scale(#{1/dpiScale},#{1/dpiScale})"
-      textRef.current.style.transformOrigin = "0% 0%"
       textRender = pdfjs.renderTextLayer
-        textContentStream: page.streamTextContent()
+        textContentSource: page.streamTextContent()
         container: textRef.current
         viewport: scaledViewport
         isOffscreenCanvasSupported: true
@@ -175,6 +176,8 @@ WrappedMessagePDF = React.memo ({file}) ->
     =>
       canceled = true
       renderTask.cancel()
+      textRender?.cancel()
+      textRef.current?.innerHTML = ''
   , [page, elementWidth, fit, inView]
 
   ## Synchronize page input with navigation of page number
@@ -290,7 +293,6 @@ WrappedMessagePDF = React.memo ({file}) ->
       <div className="annotations" ref={textRef}/>
       <div className="annotations" style={
         transform: annotationsTransform
-        transformOrigin: "0% 0%"
       }>
         {for annotation in annotations
           continue unless annotation.subtype == 'Link'
diff --git a/client/message.styl b/client/message.styl
index b663d59..2362a73 100644
--- a/client/message.styl
+++ b/client/message.styl
@@ -429,6 +429,8 @@ nav.contents
 .pdfBox
   width: 100%
 .pdf
+  > *
+    transform-origin: 0% 0%
   > svg
     width: 100%
     height: auto
@@ -441,14 +443,19 @@ nav.contents
       border: solid hsla(250,75%,50%,33%)
       &:hover
         border: solid hsla(250,75%,50%,66%)
-    > span
+    > span, > br
       position: absolute
       cursor: text
       text-align: initial
       white-space: pre
       transform-origin: 0% 0%
-      width: max-content
-      color: purple
+      color: transparent
+      opacity: 25%
+    ::selection
+      background: blue
+      background: AccentColor
+    > br::selection
+      background: transparent
 @media print
   .pdf > .annotations
     display: none
diff --git a/package.json b/package.json
index 5f32dd8..add54f7 100644
--- a/package.json
+++ b/package.json
@@ -51,8 +51,8 @@
     "markdown-it-anchor": "8.6.4",
     "markdown-it-replacements": "1.0.2",
     "markdown-it-task-checkbox": "1.0.6",
-    "meteor-node-stubs": "^1.0.1",
-    "pdfjs-dist": "2.5.207",
+    "meteor-node-stubs": "1.2.7",
+    "pdfjs-dist": "3.11.174",
     "react": "^17.0.1",
     "react-bootstrap": "^1.4.3",
     "react-bootstrap-typeahead": "^5.1.4",