From 73b7422c6b7dce14da456bf12c7c65c7301dc2e8 Mon Sep 17 00:00:00 2001
From: Brian Button <brian.button@yuppiechef.com>
Date: Fri, 15 Jan 2021 13:22:19 +0200
Subject: [PATCH] Added the ability to overlay one PDF over another

---
 CHANGELOG.md                    |  1 +
 README.md                       | 10 +++++++
 src/pdfboxing/overlay.clj       | 47 +++++++++++++++++++++++++++++++++
 test/pdfboxing/overlay_test.clj | 27 +++++++++++++++++++
 4 files changed, 85 insertions(+)
 create mode 100644 src/pdfboxing/overlay.clj
 create mode 100644 test/pdfboxing/overlay_test.clj

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8a59b71..aca5694 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Added
 - Added the ability to merge multiple images into a single PDF
 - Added the ability to load PDFs from byte arrays
+- Added the ability to overlay one PDF over another
 
 ### Changed
 - Using lists for :imports
diff --git a/README.md b/README.md
index edf9f32..02dc34a 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,16 @@ Clojure PDF manipulation library & wrapper for [PDFBox](http://pdfbox.apache.org
 (pdf/merge-pdfs :input ["test/pdfs/clojure-1.pdf" "test/pdfs/clojure-2.pdf"] :output "foo.pdf")
 ```
 
+### Overlay one PDF over another
+
+```clojure
+(require '[pdfboxing.overlay :as pdf-overlay])
+(pdf-overlay/overlay-pdf
+  {:input-file-path "test/pdfs/clojure-1.pdf"
+   :overlay-file-path "test/pdfs/clojure-2.pdf"
+   :output-file-path "test/pdfs/foo.pdf"})
+```
+
 ### Merge multiple images into single PDF
 
 You can use either `merge-images-from-path` for providing images in
diff --git a/src/pdfboxing/overlay.clj b/src/pdfboxing/overlay.clj
new file mode 100644
index 0000000..c3025e7
--- /dev/null
+++ b/src/pdfboxing/overlay.clj
@@ -0,0 +1,47 @@
+(ns pdfboxing.overlay
+  (:import
+    (org.apache.pdfbox.multipdf Overlay)))
+
+(defn overlay-pdf
+  "overlay one PDF over another"
+  [{:keys
+    [input-file-path
+     input-pdf
+     overlay-file-path
+     overlay-pdf
+     first-page-overlay-pdf
+     first-page-overlay-file-path
+     last-page-overlay-file-path
+     last-page-overlay-pdf
+     all-page-overlay-file-path
+     all-page-overlay-pdf
+     odd-page-overlay-file-path
+     odd-page-overlay-pdf
+     even-page-overlay-file-path
+     even-page-overlay-pdf
+     ^String output-file-path]}]
+
+  (let [overlay (Overlay.)]
+    (.setInputFile overlay input-file-path)
+    (.setInputPDF overlay input-pdf)
+
+    (.setDefaultOverlayFile overlay overlay-file-path)
+    (.setDefaultOverlayPDF overlay overlay-pdf)
+
+    (.setFirstPageOverlayFile overlay first-page-overlay-file-path)
+    (.setFirstPageOverlayPDF overlay first-page-overlay-pdf)
+
+    (.setLastPageOverlayFile overlay last-page-overlay-file-path)
+    (.setLastPageOverlayPDF overlay last-page-overlay-pdf)
+
+    (.setAllPagesOverlayFile overlay all-page-overlay-file-path)
+    (.setAllPagesOverlayPDF overlay all-page-overlay-pdf)
+
+    (.setOddPageOverlayFile overlay odd-page-overlay-file-path)
+    (.setOddPageOverlayPDF overlay odd-page-overlay-pdf)
+
+    (.setEvenPageOverlayFile overlay even-page-overlay-file-path)
+    (.setEvenPageOverlayPDF overlay even-page-overlay-pdf)
+
+    (-> overlay (.overlay {}) (.save output-file-path))
+    (.close overlay)))
\ No newline at end of file
diff --git a/test/pdfboxing/overlay_test.clj b/test/pdfboxing/overlay_test.clj
new file mode 100644
index 0000000..6846305
--- /dev/null
+++ b/test/pdfboxing/overlay_test.clj
@@ -0,0 +1,27 @@
+(ns pdfboxing.overlay-test
+  (:require
+    [clojure.java.io :as io]
+    [clojure.test :refer [deftest is]]
+    [pdfboxing.common :as common]
+    [pdfboxing.overlay :refer [overlay-pdf]]))
+
+(def output-file-path "test/pdfs/foo.pdf")
+
+(deftest pdf-file-merge
+  (let [_
+        (overlay-pdf
+          {:input-file-path "test/pdfs/clojure-1.pdf"
+           :overlay-file-path "test/pdfs/clojure-2.pdf"
+           :output-file-path output-file-path})
+
+        overlayed-pdf-file (.exists (io/as-file output-file-path))]
+    (is (true? overlayed-pdf-file))
+    (is (true? (common/is-pdf? output-file-path)))))
+
+;; clean up
+(defn clean-up [file]
+  (if (.exists (io/as-file file))
+    (io/delete-file file)))
+
+(deftest cleaner
+  (clean-up "test/pdfs/foo.pdf"))