From b83de09f9e7bddfff5d5fefba600d26fcd6f3a64 Mon Sep 17 00:00:00 2001
From: gered <gered@blarg.ca>
Date: Wed, 16 Aug 2017 19:57:55 -0400
Subject: [PATCH] add image watermark rendering support

---
 src/clj_htmltopdf/watermark.clj | 75 ++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 21 deletions(-)

diff --git a/src/clj_htmltopdf/watermark.clj b/src/clj_htmltopdf/watermark.clj
index ef46dae..941b27f 100644
--- a/src/clj_htmltopdf/watermark.clj
+++ b/src/clj_htmltopdf/watermark.clj
@@ -1,9 +1,12 @@
 (ns clj-htmltopdf.watermark
+  (:require
+    [clojure.java.io :as io])
   (:import
     [java.io InputStream OutputStream]
     [org.apache.pdfbox.pdmodel PDDocument PDPage PDPageContentStream PDPageContentStream$AppendMode]
     [org.apache.pdfbox.pdmodel.common PDRectangle]
     [org.apache.pdfbox.pdmodel.font PDType1Font PDFont]
+    [org.apache.pdfbox.pdmodel.graphics.image PDImageXObject PDImage]
     [org.apache.pdfbox.pdmodel.graphics.state PDExtendedGraphicsState]
     [org.apache.pdfbox.util Matrix]))
 
@@ -24,25 +27,25 @@
    "courier-oblique"       PDType1Font/COURIER_OBLIQUE
    "courier-boldoblique"   PDType1Font/COURIER_BOLD_OBLIQUE})
 
-(defn render-watermark!
-  [^PDPage page ^PDPageContentStream cs options]
-  (let [font          (or (get watermark-fonts (:font options))
-                          (get watermark-fonts "helvetica-bold"))
-        font-size     (float (or (:font-size options) 36.0))
-        font-color    (or (:color options) [0 0 0])
-        text          (:text options)
-        text-width    (/ (* (.getStringWidth font text) font-size) 1000.0)
-        text-height   (/ (* (.getHeight (.getFontBoundingBox (.getFontDescriptor ^PDFont font))) font-size) 1000.0)
-        rotation      (float (or (:rotation options) 0))
-        page-size     (.getMediaBox page)
-        page-width    (.getWidth page-size)
-        page-height   (.getHeight page-size)
-        x             (if (= :center (:x options)) (/ page-width 2) (float (:x options)))
-        y             (if (= :center (:y options)) (/ page-height 2) (float (:y options)))
-        transform     (doto (Matrix.)
-                        (.translate x y)
-                        (.rotate (Math/toRadians rotation))
-                        (.translate (- (/ text-width 2)) (- (/ text-height 2))))]
+(defn render-text-watermark!
+  [^PDDocument doc ^PDPage page ^PDPageContentStream cs options]
+  (let [font        (or (get watermark-fonts (:font options))
+                        (get watermark-fonts "helvetica-bold"))
+        font-size   (float (or (:font-size options) 36.0))
+        font-color  (or (:color options) [0 0 0])
+        text        (:text options)
+        text-width  (/ (* (.getStringWidth font text) font-size) 1000.0)
+        text-height (/ (* (.getHeight (.getFontBoundingBox (.getFontDescriptor ^PDFont font))) font-size) 1000.0)
+        rotation    (float (or (:rotation options) 0))
+        page-size   (.getMediaBox page)
+        page-width  (.getWidth page-size)
+        page-height (.getHeight page-size)
+        x           (if (= :center (:x options)) (/ page-width 2) (float (:x options)))
+        y           (if (= :center (:y options)) (/ page-height 2) (float (:y options)))
+        transform   (doto (Matrix.)
+                      (.translate x y)
+                      (.rotate (Math/toRadians rotation))
+                      (.translate (- (/ text-width 2)) (- (/ text-height 2))))]
     (when (:opacity options)
       (let [r0 (PDExtendedGraphicsState.)]
         (.setNonStrokingAlphaConstant r0 (float (:opacity options)))
@@ -54,6 +57,36 @@
     (.showText cs text)
     (.endText cs)))
 
+(defn render-image-watermark!
+  [^PDDocument doc ^PDPage page ^PDPageContentStream cs options]
+  (let [image        (PDImageXObject/createFromFileByContent (io/file (:image options)) doc)
+        image-width  (.getWidth image)
+        image-height (.getHeight image)
+        rotation     (float (or (:rotation options) 0))
+        page-size    (.getMediaBox page)
+        page-width   (.getWidth page-size)
+        page-height  (.getHeight page-size)
+        x            (if (= :center (:x options)) (/ page-width 2) (float (:x options)))
+        y            (if (= :center (:y options)) (/ page-height 2) (float (:y options)))
+        transform    (doto (Matrix.)
+                       (.translate x y)
+                       (.scale (or (:scale-x options) 1.0) (or (:scale-y options) 1.0))
+                       (.rotate (Math/toRadians rotation))
+                       (.translate (- (/ image-width 2)) (- (/ image-height 2))))]
+    (when (:opacity options)
+      (let [r0 (PDExtendedGraphicsState.)]
+        (.setNonStrokingAlphaConstant r0 (float (:opacity options)))
+        (.setGraphicsStateParameters cs r0)))
+    (.transform cs transform)
+    (.drawImage cs image (float 0) (float 0))))
+
+(defn render-watermark!
+  [^PDDocument doc ^PDPage page ^PDPageContentStream cs options]
+  (cond
+    (:text options)  (render-text-watermark! doc page cs options)
+    (:image options) (render-image-watermark! doc page cs options)
+    :else            (throw (Exception. "Unknown type of watermark. Either :text or :image should be specified."))))
+
 (defn write-watermark!
   [^InputStream pdf ^OutputStream out {:keys [watermark] :as options}]
   (with-open [doc (PDDocument/load pdf)]
@@ -61,7 +94,7 @@
       (let [cs (PDPageContentStream. doc page PDPageContentStream$AppendMode/APPEND true true)]
         (with-open [cs cs]
           (if (map? watermark)
-            (render-watermark! page cs watermark)
-            (watermark page cs)))))
+            (render-watermark! doc page cs watermark)
+            (watermark doc page cs)))))
     (.save doc out)
     out))