FOP-3293: Support for caching of pdf image object streams

Author: simonsteiner1984

fop-core/src/main/java/org/apache/fop/apps/FOUserAgent.java

@@ -69,6 +69,7 @@
 import org.apache.fop.render.intermediate.IFDocumentHandler;
 import org.apache.fop.util.ColorSpaceCache;
 import org.apache.fop.util.ContentHandlerFactoryRegistry;
+import org.apache.fop.util.ImageObjectCache;
 
 /**
  * This is the user agent for FOP.
@@ -827,6 +828,11 @@ public ImageHandlerRegistry getImageHandlerRegistry() {
         return factory.getImageHandlerRegistry();
     }
 
+    /** @return the image object cache */
+    public ImageObjectCache getImageObjectCache() {
+        return factory.getImageObjectCache();
+    }
+
     /** @return the color space cache */
     public ColorSpaceCache getColorSpaceCache() {
         return factory.getColorSpaceCache();

fop-core/src/main/java/org/apache/fop/apps/FopConfParser.java

@@ -209,6 +209,14 @@ private void configure(final URI baseURI, final ResourceResolver resourceResolve
             }
         }
 
+        if (cfg.getChild("image-cache", false) != null) {
+            try {
+                fopFactoryBuilder.setImageCache(cfg.getChild("image-cache").getValueAsBoolean());
+            } catch (ConfigurationException e) {
+                LogUtil.handleException(LOG, e, false);
+            }
+        }
+
         // base definitions for relative path resolution
         if (cfg.getChild("base", false) != null) {
             try {

fop-core/src/main/java/org/apache/fop/apps/FopFactory.java

@@ -56,6 +56,8 @@
 import org.apache.fop.render.XMLHandlerRegistry;
 import org.apache.fop.util.ColorSpaceCache;
 import org.apache.fop.util.ContentHandlerFactoryRegistry;
+import org.apache.fop.util.ImageObjectCache;
+import org.apache.fop.util.ImageObjectCacheImpl;
 
 /**
  * Factory class which instantiates new Fop and FOUserAgent instances. This
@@ -86,6 +88,7 @@ public final class FopFactory implements ImageContext {
 
     private final ColorSpaceCache colorSpaceCache;
 
+    private final ImageObjectCache imageObjectCache;
     private final FopFactoryConfig config;
 
     private final InternalResourceResolver resolver;
@@ -103,6 +106,11 @@ private FopFactory(FopFactoryConfig config) {
                 config.getResourceResolver());
         this.elementMappingRegistry = new ElementMappingRegistry(this);
         this.colorSpaceCache = new ColorSpaceCache(resolver);
+        if (config.isImageCacheEnabled()) {
+            this.imageObjectCache = new ImageObjectCacheImpl();
+        } else {
+            this.imageObjectCache = new ImageObjectCache();
+        }
         this.rendererFactory = new RendererFactory(config.preferRenderer());
         this.xmlHandlers = new XMLHandlerRegistry();
         this.imageHandlers = new ImageHandlerRegistry();
@@ -495,6 +503,14 @@ FallbackResolver getFallbackResolver() {
         return config.getFallbackResolver();
     }
 
+    /**
+     * Returns the ImageObjectCache for this instance.
+     * @return the image object cache
+     */
+    public ImageObjectCache getImageObjectCache() {
+        return this.imageObjectCache;
+    }
+
     /**
      * Returns the color space cache for this instance.
      * <p>

fop-core/src/main/java/org/apache/fop/apps/FopFactoryBuilder.java

@@ -172,6 +172,11 @@ public FopFactoryBuilder setKeepEmptyTags(boolean b) {
         return this;
     }
 
+    public FopFactoryBuilder setImageCache(boolean b) {
+        fopFactoryConfigBuilder.setImageCache(b);
+        return this;
+    }
+
     /**
      * Sets the {@link LayoutManagerMaker} so that users can configure how FOP creates
      * {@link org.apache.fop.layoutmgr.LayoutManager}s.
@@ -392,6 +397,8 @@ public static class FopFactoryConfigImpl implements FopFactoryConfig {
 
         private boolean keepEmptyTags = true;
 
+        private boolean imageCache = true;
+
         private LayoutManagerMaker layoutManagerMaker;
 
         private URI baseURI;
@@ -468,6 +475,10 @@ public boolean isKeepEmptyTags() {
             return keepEmptyTags;
         }
 
+        public boolean isImageCacheEnabled() {
+            return imageCache;
+        }
+
         /** {@inheritDoc} */
         public LayoutManagerMaker getLayoutManagerMakerOverride() {
             return layoutManagerMaker;
@@ -601,6 +612,8 @@ private interface FopFactoryConfigBuilder {
 
         void setKeepEmptyTags(boolean b);
 
+        void setImageCache(boolean b);
+
         void setLayoutManagerMakerOverride(LayoutManagerMaker lmMaker);
 
         void setBaseURI(URI baseURI);
@@ -669,6 +682,10 @@ public void setKeepEmptyTags(boolean b) {
             throwIllegalStateException();
         }
 
+        public void setImageCache(boolean b) {
+            throwIllegalStateException();
+        }
+
         public void setLayoutManagerMakerOverride(LayoutManagerMaker lmMaker) {
             throwIllegalStateException();
 
@@ -784,6 +801,10 @@ public void setKeepEmptyTags(boolean b) {
             config.keepEmptyTags = b;
         }
 
+        public void setImageCache(boolean b) {
+            config.imageCache = b;
+        }
+
         public void setLayoutManagerMakerOverride(LayoutManagerMaker lmMaker) {
             config.layoutManagerMaker = lmMaker;
         }

fop-core/src/main/java/org/apache/fop/apps/FopFactoryConfig.java

@@ -77,6 +77,8 @@ public interface FopFactoryConfig {
 
     boolean isKeepEmptyTags();
 
+    boolean isImageCacheEnabled();
+
     /**
      * Returns the overriding LayoutManagerMaker instance, if any.
      * @return the overriding LayoutManagerMaker or null

fop-core/src/main/java/org/apache/fop/pdf/AlphaRasterImage.java

@@ -41,6 +41,8 @@ public class AlphaRasterImage implements PDFImage {
     private Raster alpha;
     private String key;
 
+    private ImageObjectStream imageObjectStream;
+
     /**
      * Create a alpha channel image.
      * Creates a new bitmap image with the given data.
@@ -248,6 +250,13 @@ public PDFFilter getPDFFilter() {
     }
 
     /** {@inheritDoc} */
+    public void outputImageData(OutputStream out) throws IOException {
+        if (imageObjectStream == null) {
+            imageObjectStream = new ImageObjectStream(this);
+        }
+        imageObjectStream.outputImageData(out);
+    }
+
     public boolean multipleFiltersAllowed() {
         return true;
     }

fop-core/src/main/java/org/apache/fop/pdf/BitmapImage.java

@@ -40,6 +40,8 @@ public class BitmapImage implements PDFImage {
     private PDFFilter pdfFilter;
     private boolean multipleFiltersAllowed = true;
 
+    private ImageObjectStream imageObjectStream;
+
     /**
      * Create a bitmap image.
      * Creates a new bitmap image with the given data.
@@ -217,6 +219,14 @@ public void setPDFFilter(PDFFilter pdfFilter) {
         this.pdfFilter = pdfFilter;
     }
 
+    /** {@inheritDoc} */
+    public void outputImageData(OutputStream out) throws IOException {
+        if (imageObjectStream == null) {
+            imageObjectStream = new ImageObjectStream(this);
+        }
+        imageObjectStream.outputImageData(out);
+    }
+
     /** {@inheritDoc} */
     public boolean multipleFiltersAllowed() {
         return multipleFiltersAllowed;

fop-core/src/main/java/org/apache/fop/pdf/ImageObjectStream.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.fop.pdf;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+public class ImageObjectStream {
+
+    private PDFImage pdfImage;
+    private byte[] pdfStreamBytes;
+
+    public ImageObjectStream(PDFImage img) {
+        pdfImage = img;
+    }
+
+    public void outputImageData(OutputStream out) throws IOException {
+        if (pdfStreamBytes == null) {
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            pdfImage.outputContents(baos);
+            pdfStreamBytes = baos.toByteArray();
+        }
+        out.write(pdfStreamBytes);
+    }
+}

fop-core/src/main/java/org/apache/fop/pdf/PDFImage.java

@@ -22,11 +22,13 @@
 import java.io.IOException;
 import java.io.OutputStream;
 
+import org.apache.fop.util.ImageObject;
+
 /**
  * Interface for a PDF image.
  * This is used for inserting an image into PDF.
  */
-public interface PDFImage {
+public interface PDFImage extends ImageObject {
 
     /**
      * Key to look up XObject.
@@ -158,6 +160,13 @@ public interface PDFImage {
      */
     String getFilterHint();
 
+    /**
+     * Writes a possibly previously cached stream of bytes that represent the image.
+     * @param out OutputStream to write to
+     * @throws IOException if issues happen when writing the stream
+     */
+    void outputImageData(OutputStream out) throws IOException;
+
     /**
      * Indicates whether multiple image filters are allowed; this is implemented because Adobe
      * Reader does not like multiple FlateDecode filters applied to an image even though that

fop-core/src/main/java/org/apache/fop/pdf/PDFImageXObject.java

@@ -23,6 +23,7 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.lang.ref.SoftReference;
 import java.util.Set;
 import java.util.UUID;
 
@@ -42,6 +43,7 @@
 public class PDFImageXObject extends PDFXObject {
 
     private PDFImage pdfimage;
+    private SoftReference<PDFImage> softReferencePdfimage;
 
     /**
      * create an XObject with the given number and name and load the
@@ -54,6 +56,7 @@ public PDFImageXObject(int xnumber, PDFImage img) {
         super();
         put("Name", new PDFName("Im" + xnumber));
         pdfimage = img;
+        softReferencePdfimage = new SoftReference<>(img);
     }
 
     /**
@@ -67,7 +70,7 @@ public PDFImageXObject(int xnumber, PDFImage img) {
     public int output(OutputStream stream) throws IOException {
         if (getDocument().getProfile().isPDFVTActive()) {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            pdfimage.outputContents(baos);
+            pdfimage.outputImageData(baos);
             put("GTS_XID", "uuid:" + UUID.nameUUIDFromBytes(baos.toByteArray()));
         }
         int length = super.output(stream);
@@ -150,7 +153,7 @@ private void populateDictionaryFromImage() {
 
     /** {@inheritDoc} */
     protected void outputRawStreamData(OutputStream out) throws IOException {
-        pdfimage.outputContents(out);
+        pdfimage.outputImageData(out);
     }
 
     /** {@inheritDoc} */
@@ -174,6 +177,14 @@ protected String getDefaultFilterName() {
         return pdfimage.getFilterHint();
     }
 
+    /**
+     * Returns the associated PDFImage.
+     * @return the PDFImage associated with this XObject
+     */
+    public PDFImage getPDFImage() {
+        return softReferencePdfimage.get();
+    }
+
     /** {@inheritDoc} */
     protected boolean multipleFiltersAllowed() {
         return pdfimage.multipleFiltersAllowed();