fix page size of some externally added pages

Refs rkusa#111

Author: rkusa

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Pages from external documents should always be added with their original size #111
 
 ## [2.1.0] - 2018-09-22
 ### Changed

lib/external.js

@@ -12,13 +12,20 @@ module.exports = class ExternalDocument {
     const pages    = catalog.get('Pages').object.properties
 
     this.pages = pages
+    const mediaBox = pages.get('MediaBox')
     const kids = pages.get('Kids')
     this.pageCount = kids.length
 
     this.objects = []
     for (const kid of kids) {
       const page = kid.object
 
+      // if the page object does not define its MediaBox, explicitly set its MediaBox to the
+      // value defined by its parent Pages object
+      if (!page.properties.has('MediaBox') && mediaBox) {
+        page.properties.set('MediaBox', mediaBox)
+      }
+
       const objects = []
       Parser.addObjectsRecursive(objects, page)
 

test/pdfs/external/fixtures/200x200.pdf

@@ -0,0 +1,12 @@
+module.exports = function(doc, {document}) {
+  doc.text('First')
+
+  const pdf = require('../../../')
+  const path = require('path')
+  const fs = require('fs')
+
+  const external = new pdf.ExternalDocument(fs.readFileSync(path.join(__dirname, '/fixtures/200x200.pdf')))
+  doc.addPagesOf(external)
+
+  doc.text('Second')
+}