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add support for caching xobject images with watermark rendering

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Gered 2017-08-29 14:37:01 -04:00
parent d7526ae11a
commit f74f879759
1 changed files with 27 additions and 8 deletions
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35
src/clj_htmltopdf/watermark.clj
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@ -2,7 +2,7 @@
(:require
[clojure.java.io :as io])
(:import
[java.io InputStream OutputStream]
[java.io File InputStream OutputStream]
[org.apache.pdfbox.pdmodel PDDocument PDPage PDPageContentStream PDPageContentStream$AppendMode]
[org.apache.pdfbox.pdmodel.common PDRectangle]
[org.apache.pdfbox.pdmodel.font PDType1Font PDFont]
@ -10,6 +10,24 @@
[org.apache.pdfbox.pdmodel.graphics.state PDExtendedGraphicsState]
[org.apache.pdfbox.util Matrix]))
(declare ^:dynamic *pdf-images*)
(defn create-pdf-image
"Creates an XObject image from an image file. Caches this XObject for this particular PDF document so that if the
image is rendered into the PDF multiple times, the PDF will reference the same image instead of creating duplicates
(which would potentially bump up the file size drastically).
This function must only be called from within code invoked by write-watermark!."
^PDImageXObject [file ^PDDocument doc]
(if-not *pdf-images*
(throw (ex-info "Could not create PDF XObject image. Image cache has not been initialized." {:file file})))
(let [image-file (io/file file)
path (.getPath image-file)]
(if-let [existing-image (get @*pdf-images* path)]
existing-image
(let [image (PDImageXObject/createFromFileByContent image-file doc)]
(swap! *pdf-images* assoc path image)
image))))
; TODO: this is a temporary measure to allow at least _some_ font customizability for watermarks
; until something more comprehensive can be implemented such as allowing loading of external
; TTF fonts via PDTrueTypeFont.loadTTF()
@ -59,7 +77,7 @@
(defn render-image-watermark!
[^PDDocument doc ^PDPage page ^PDPageContentStream cs options]
(let [image (PDImageXObject/createFromFileByContent (io/file (:image options)) doc)
(let [image (create-pdf-image (:image options) doc)
image-width (.getWidth image)
image-height (.getHeight image)
rotation (float (or (:rotation options) 0))
@ -90,11 +108,12 @@
(defn write-watermark!
[^InputStream pdf ^OutputStream out {:keys [watermark] :as options}]
(with-open [doc (PDDocument/load pdf)]
(doseq [^PDPage page (.getPages doc)]
(let [cs (PDPageContentStream. doc page PDPageContentStream$AppendMode/APPEND true true)]
(with-open [cs cs]
(if (map? watermark)
(render-watermark! doc page cs watermark)
(watermark doc page cs)))))
(binding [*pdf-images* (atom {})]
(doseq [^PDPage page (.getPages doc)]
(let [cs (PDPageContentStream. doc page PDPageContentStream$AppendMode/APPEND true true)]
(with-open [cs cs]
(if (map? watermark)
(render-watermark! doc page cs watermark)
(watermark doc page cs))))))
(.save doc out)
out))