[ADD] TTFDataStream.createSubView() to create a subview without copying arrays

[ADD] RandomAccessReadUncachedDataStream that doesn't read input stream to byte[]

Author: bogdiuk

fontbox/src/main/java/org/apache/fontbox/ttf/RandomAccessReadDataStream.java

@@ -19,9 +19,12 @@
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 
 import org.apache.pdfbox.io.IOUtils;
 import org.apache.pdfbox.io.RandomAccessRead;
+import org.apache.pdfbox.io.RandomAccessReadBuffer;
 
 /**
  * An implementation of the TTFDataStream using RandomAccessRead as source.
@@ -30,6 +33,8 @@
  */
 class RandomAccessReadDataStream extends TTFDataStream
 {
+    private static final Log LOG = LogFactory.getLog(RandomAccessReadDataStream.class);
+
     private final long length;
     private final byte[] data;
     private int currentPosition = 0;
@@ -174,6 +179,20 @@ public int read(byte[] b, int off, int len) throws IOException
         return bytesToRead;
     }
 
+    @Override
+    public RandomAccessRead createSubView(long length)
+    {
+        try
+        {
+            return new RandomAccessReadBuffer(data).createView(currentPosition, length);
+        }
+        catch (IOException e)
+        {
+            LOG.warn("Could not create a SubView", e);
+            return null;
+        }
+    }
+
     /**
      * {@inheritDoc}
      */

fontbox/src/main/java/org/apache/fontbox/ttf/RandomAccessReadUnbufferedDataStream.java

@@ -0,0 +1,188 @@
+/*
+ * 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.fontbox.ttf;
+
+import java.io.IOException;
+import java.io.InputStream;
+import org.apache.pdfbox.io.RandomAccessRead;
+import org.apache.pdfbox.io.RandomAccessReadView;
+
+/**
+ * In contrast to {@link RandomAccessReadDataStream},
+ * this class doesn't pre-load {@code RandomAccessRead} into a {@code byte[]},
+ * it works with {@link RandomAccessRead} directly.
+ * 
+ * Performance: it is much faster if most of the buffer is skipped, and slower if whole buffer is read()
+ */
+class RandomAccessReadUnbufferedDataStream extends TTFDataStream
+{
+    private final long length;
+    private final RandomAccessRead randomAccessRead;
+
+    /**
+     * @throws IOException If there is a problem reading the source length.
+     */
+    RandomAccessReadUnbufferedDataStream(RandomAccessRead randomAccessRead) throws IOException
+    {
+        this.length = randomAccessRead.length();
+        this.randomAccessRead = randomAccessRead;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public long getCurrentPosition() throws IOException
+    {
+        return randomAccessRead.getPosition();
+    }
+
+    /**
+     * Close the underlying resources.
+     *
+     * @throws IOException If there is an error closing the resources.
+     */
+    @Override
+    public void close() throws IOException
+    {
+        randomAccessRead.close();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public int read() throws IOException
+    {
+        return randomAccessRead.read();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public final long readLong() throws IOException
+    {
+        return ((long) readInt() << 32) | (readInt() & 0xFFFFFFFFL);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    private int readInt() throws IOException
+    {
+        int b1 = read();
+        int b2 = read();
+        int b3 = read();
+        int b4 = read();
+        return (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void seek(long pos) throws IOException
+    {
+        randomAccessRead.seek(pos);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public int read(byte[] b, int off, int len) throws IOException
+    {
+        randomAccessRead.read(b, off, len);
+        return len;
+    }
+
+    /**
+     * Lifetime of returned InputStream is bound by {@code this} lifetime, it won't close underlying {@code RandomAccessRead}.
+     * 
+     * {@inheritDoc}
+     */
+    @Override
+    public InputStream getOriginalData() throws IOException
+    {
+        return new RandomAccessReadNonClosingInputStream(randomAccessRead.createView(0, length));
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public long getOriginalDataSize()
+    {
+        return length;
+    }
+
+    @Override
+    public RandomAccessRead createSubView(long length)
+    {
+        try
+        {
+            return randomAccessRead.createView(randomAccessRead.getPosition(), length);
+        }
+        catch (IOException ex)
+        {
+            assert false : "Please implement " + randomAccessRead.getClass() + ".createView()";
+            return null;
+        }
+    }
+
+    private static final class RandomAccessReadNonClosingInputStream extends InputStream {
+
+        private final RandomAccessReadView randomAccessRead;
+
+        public RandomAccessReadNonClosingInputStream(RandomAccessReadView randomAccessRead)
+        {
+            this.randomAccessRead = randomAccessRead;
+        }
+
+        @Override
+        public int read() throws IOException
+        {
+            return randomAccessRead.read();
+        }
+
+        @Override
+        public int read(byte[] b) throws IOException
+        {
+            return randomAccessRead.read(b);
+        }
+
+        @Override
+        public int read(byte[] b, int off, int len) throws IOException
+        {
+            return randomAccessRead.read(b, off, len);
+        }
+
+        @Override
+        public long skip(long n) throws IOException
+        {
+            randomAccessRead.seek(randomAccessRead.getPosition() + n);
+            return n;
+        }
+
+        @Override
+        public void close() throws IOException {
+            // WARNING: .close() will close RandomAccessReadMemoryMappedFile if this View was based on it
+//            randomAccessRead.close();
+        }
+    }
+}

fontbox/src/main/java/org/apache/fontbox/ttf/TTCDataStream.java

@@ -19,6 +19,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import org.apache.pdfbox.io.RandomAccessRead;
 
 /**
  * A wrapper for a TTF stream inside a TTC file, does not close the underlying shared stream.
@@ -83,4 +84,9 @@ public long getOriginalDataSize()
         return stream.getOriginalDataSize();
     }
 
+    @Override
+    public RandomAccessRead createSubView(long length)
+    {
+        return stream.createSubView(length);
+    }
 }

fontbox/src/main/java/org/apache/fontbox/ttf/TTFDataStream.java

@@ -24,6 +24,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Calendar;
 import java.util.TimeZone;
+import org.apache.pdfbox.io.RandomAccessRead;
 
 /**
  * An abstract class to read a data stream.
@@ -279,6 +280,17 @@ public byte[] read(int numberOfBytes) throws IOException
      */
     public abstract int read(byte[] b, int off, int len) throws IOException;
 
+    /**
+     * Creates a view from current position to {@code pos + length}.
+     * It can be faster than {@code read(length)} if you only need a few bytes.
+     * {@code SubView.close()} should never close {@code TTFDataStream.this}, only itself.
+     *
+     * @return A view or null (caller can use {@link #read} instead). Please close() the result
+     */
+    public /*@Nullable*/ RandomAccessRead createSubView(long length) {
+        return null;
+    }
+
     /**
      * Get the current position in the stream.
      *

fontbox/src/main/java/org/apache/fontbox/ttf/TrueTypeCollection.java

@@ -47,7 +47,7 @@ public class TrueTypeCollection implements Closeable
      */
     public TrueTypeCollection(File file) throws IOException
     {
-        this(new RandomAccessReadBufferedFile(file), true);
+        this(new RandomAccessReadBufferedFile(file), true, true);
     }
 
     /**
@@ -58,7 +58,7 @@ public TrueTypeCollection(File file) throws IOException
      */
     public TrueTypeCollection(InputStream stream) throws IOException
     {
-        this(new RandomAccessReadBuffer(stream), false);
+        this(new RandomAccessReadBuffer(stream), false, true);
     }
 
     /**
@@ -69,21 +69,24 @@ public TrueTypeCollection(InputStream stream) throws IOException
      */
     TrueTypeCollection(RandomAccessRead randomAccessRead) throws IOException
     {
-        this(randomAccessRead, false);
+        this(randomAccessRead, false, true);
     }
 
     /**
      * Creates a new TrueTypeCollection from a RandomAccessRead.
      *
      * @param randomAccessRead 
      * @param closeAfterReading {@code true} to close randomAccessRead
+     * @param buffered {@code true} to use {@link RandomAccessReadDataStream}, {@code false} to use {@link RandomAccessReadUnbufferedDataStream}
      * @throws IOException If the font could not be parsed.
      */
-    private TrueTypeCollection(RandomAccessRead randomAccessRead, boolean closeAfterReading) throws IOException
+    private TrueTypeCollection(RandomAccessRead randomAccessRead, boolean closeAfterReading, boolean buffered) throws IOException
     {
         try
         {
-            this.stream = new RandomAccessReadDataStream(randomAccessRead);
+            this.stream = buffered
+                    ? new RandomAccessReadDataStream(randomAccessRead)
+                    : new RandomAccessReadUnbufferedDataStream(randomAccessRead);
         }
         finally
         {
@@ -118,7 +121,19 @@ private TrueTypeCollection(RandomAccessRead randomAccessRead, boolean closeAfter
             int ulDsigOffset = stream.readUnsignedShort();
         }
     }
-    
+
+    /**
+     * Creates a new TrueTypeCollection without reading the whole .ttc file.
+     * It is important to {@link #close()} the resulting {@link TrueTypeCollection} to dispose the FileChannel.
+     *
+     * @param file The TTC file.
+     * @throws IOException If the font could not be parsed.
+     */
+    public static TrueTypeCollection createUnbuffered(File file) throws IOException
+    {
+        return new TrueTypeCollection(new RandomAccessReadBufferedFile(file), false, false);
+    }
+
     /**
      * Run the callback for each TT font in the collection.
      *