ImageReader implementing class for PNG images

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@193632 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/src/org/apache/fop/image/analyser/PNGReader.java b/src/org/apache/fop/image/analyser/PNGReader.java
new file mode 100644 (file)
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+++ b/src/org/apache/fop/image/analyser/PNGReader.java
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+/*
+ ============================================================================
+                   The Apache Software License, Version 1.1
+ ============================================================================
+    Copyright (C) 1999 The Apache Software Foundation. All rights reserved.
+ Redistribution and use in source and binary forms, with or without modifica-
+ tion, are permitted provided that the following conditions are met:
+ 1. Redistributions of  source code must  retain the above copyright  notice,
+    this list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+ 3. The end-user documentation included with the redistribution, if any, must
+    include  the following  acknowledgment:  "This product includes  software
+    developed  by the  Apache Software Foundation  (http://www.apache.org/)."
+    Alternately, this  acknowledgment may  appear in the software itself,  if
+    and wherever such third-party acknowledgments normally appear.
+ 4. The names "Fop" and  "Apache Software Foundation"  must not be used to
+    endorse  or promote  products derived  from this  software without  prior
+    written permission. For written permission, please contact
+    apache@apache.org.
+ 5. Products  derived from this software may not  be called "Apache", nor may
+    "Apache" appear  in their name,  without prior written permission  of the
+    Apache Software Foundation.
+ THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
+ INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
+ APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
+ INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLU-
+ DING, BUT NOT LIMITED TO, PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND ON
+ ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR TORT
+ (INCLUDING  NEGLIGENCE OR  OTHERWISE) ARISING IN  ANY WAY OUT OF THE  USE OF
+ THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ This software  consists of voluntary contributions made  by many individuals
+ on  behalf of the Apache Software  Foundation and was  originally created by
+ James Tauber <jtauber@jtauber.com>. For more  information on the Apache
+ Software Foundation, please see <http://www.apache.org/>.
+ */
+
+package org.apache.fop.image.analyser;
+
+// Java
+import java.io.BufferedInputStream;
+import java.io.IOException;
+
+/**
+ * ImageReader object for PNG image type.
+ * @author Pankaj Narula
+ * @version 1.0
+ */
+public class PNGReader extends AbstractImageReader {
+  static protected final int PNG_SIG_LENGTH = 24;
+  protected byte[] header;
+
+  public boolean verifySignature(BufferedInputStream fis) throws IOException {
+    this.imageStream = fis;
+    this.setDefaultHeader();
+    boolean supported = ((header[0] == (byte) 0x89) &&
+                         (header[1] == (byte) 0x50) &&
+                         (header[2] == (byte) 0x4e) &&
+                         (header[3] == (byte) 0x47) &&
+                         (header[4] == (byte) 0x0d) &&
+                         (header[5] == (byte) 0x0a) &&
+                         (header[6] == (byte) 0x1a) &&
+                         (header[7] == (byte) 0x0a));
+    if (supported) {
+      setDimension();
+      return true;
+    } else
+      return false;
+  }
+
+  public String getMimeType() {
+    return "image/png";
+  }
+
+  protected void setDimension() {
+    //png is always big endian
+    int byte1 = header[16] & 0xff;
+    int byte2 = header[17] & 0xff;
+    int byte3 = header[18] & 0xff;
+    int byte4 = header[19] & 0xff;
+    long l = (long)((byte1 << 24) | (byte2 << 16) |
+                    (byte3 << 8) | byte4);
+    this.width = (int)(l);
+
+    byte1 = header[20] & 0xff;
+    byte2 = header[21] & 0xff;
+    byte3 = header[22] & 0xff;
+    byte4 = header[23] & 0xff;
+    l = (long)((byte1 << 24) | (byte2 << 16) | (byte3 << 8) |
+               byte4);
+    this.height = (int)(l);
+
+  }
+
+  protected void setDefaultHeader() throws IOException {
+    this.header = new byte[PNG_SIG_LENGTH];
+    try {
+      this.imageStream.mark(PNG_SIG_LENGTH + 1);
+      this.imageStream.read(header);
+      this.imageStream.reset();
+    } catch (IOException ex) {
+      try {
+        this.imageStream.reset();
+      } catch (IOException exbis) {}
+      throw ex;
+    }
+  }
+}
+