From Bug 38289: Yegor's support for pictures embeded in PPT files

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@369540 13f79535-47bb-0310-9956-ffa450edef68

src/scratchpad/src/org/apache/poi/hslf/HSLFSlideShow.java

@@ -36,6 +36,7 @@ import org.apache.poi.hpsf.DocumentSummaryInformation;
 import org.apache.poi.util.LittleEndian;
 
 import org.apache.poi.hslf.record.*;
+import org.apache.poi.hslf.usermodel.Picture;
 
 /**
  * This class contains the main functionality for the Powerpoint file 
@@ -337,4 +338,34 @@ public class HSLFSlideShow
   * Fetch the Current User Atom of the document
   */
  public CurrentUserAtom getCurrentUserAtom() { return currentUser; }
+
+	/**
+	 *  Read pictures contained in this presentation
+	 *
+	 *  @return array with the read pictures ot <code>null</code> if the
+	 *  presentation doesn't contain pictures.
+	 */
+	public Picture[] getPictures() throws IOException {
+		byte[] pictstream;
+
+		try {
+			DocumentEntry entry = (DocumentEntry)filesystem.getRoot().getEntry("Pictures");
+			pictstream = new byte[entry.getSize()];
+			DocumentInputStream is = filesystem.createDocumentInputStream("Pictures");
+			is.read(pictstream);
+		} catch (FileNotFoundException e){
+			//silently catch exceptions if the presentation doesn't contain pictures
+			return null;
+		}
+
+		ArrayList p = new ArrayList();
+		int pos = 0; 
+		while (pos < pictstream.length) {
+			Picture pict = new Picture(pictstream, pos);
+			p.add(pict);
+			pos += Picture.HEADER_SIZE + pict.getSize();
+		}
+
+		return (Picture[])p.toArray(new Picture[p.size()]);
+	}
 }

src/scratchpad/src/org/apache/poi/hslf/usermodel/Picture.java

@@ -0,0 +1,140 @@
+/* ====================================================================
+   Copyright 2002-2004   Apache Software Foundation
+
+   Licensed 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.poi.hslf.usermodel;
+
+import org.apache.poi.util.LittleEndian;
+
+/**
+ * Represents a picture in a PowerPoint document.
+ * <p>
+ * The information about an image in PowerPoint document is stored in 
+ * two places:
+ *  <li> EscherBSE container in the Document keeps information about image 
+ *    type, image index to refer by slides etc.
+ *  <li> "Pictures" OLE stream holds the actual data of the image.
+ * </p>
+ * <p>
+ *  Data in the "Pictures" OLE stream is organized as follows:<br>
+ *  For each image there is an entry: 25 byte header + image data.
+ *  Image data is the exact content of the JPEG file, i.e. PowerPoint
+ *  puts the whole jpeg file there without any modifications.<br>
+ *   Header format:
+ *    <li> 2 byte: image type. For JPEGs it is 0x46A0, for PNG it is 0x6E00.
+ *    <li> 2 byte: unknown.
+ *    <li> 4 byte : image size + 17. Looks like shift from the end of 
+ *          header but why to add it to the image  size?
+ *    <li> next 16 bytes. Unique identifier of this image which is used by 
+ *          EscherBSE record.
+ *  </p>
+ *
+ * @author Yegor Kozlov
+ */
+public class Picture {
+
+	/**
+	*  Windows Metafile
+	*/
+	public static final int WMF = 0x2160;
+
+	/**
+	* Macintosh PICT
+	*/
+	public static final int PICT = 0x5420;
+
+	/**
+	*  JPEG
+	*/
+	public static final int JPEG = 0x46A0;
+
+	/**
+	*  PNG
+	*/
+	public static final int PNG = 0x6E00;
+
+	/**
+	* Windows DIB (BMP)
+	*/
+	public static final int DIB = 0x7A80;
+
+	/**
+	* The size of the header
+	*/
+	public static final int HEADER_SIZE = 25;
+
+	/**
+	* Binary data of the picture
+	*/
+	protected byte[] pictdata;
+
+	/**
+	* Header which holds information about this picture
+	*/
+	protected byte[] header;
+
+	/**
+	* Read a picture from "Pictures" OLE stream
+	*
+	* @param pictstream    the bytes to read
+	* @param offset        the index of the first byte to read
+	*/
+	public Picture(byte[] pictstream, int offset){
+		header = new byte[Picture.HEADER_SIZE];
+		System.arraycopy(pictstream, offset, header, 0, header.length);
+
+		int size = LittleEndian.getInt(header, 4) - 17;
+		pictdata = new byte[size];
+		System.arraycopy(pictstream, offset + Picture.HEADER_SIZE, pictdata, 0, pictdata.length);
+	}
+
+	/**
+	* @return  the binary data of this picture
+	*/
+	public byte[] getData(){
+		return pictdata;
+	}
+
+	/**
+	* Return image size in bytes
+	*
+	* @return the size of the picture in bytes
+	*/
+	public int getSize(){
+		return pictdata.length;
+	}
+
+	/**
+	* Returns the unique identifier (UID) of this picture.
+	* The UID is a checksum of the picture data. Its length is 16 bytes
+	* and it must be unique across the presentation.
+	*
+	* @return the unique identifier of this picture
+	*/
+	public byte[] getUID(){
+		byte[] uid = new byte[16];
+		System.arraycopy(header, 8, uid, 0, uid.length);
+		return uid;
+	}
+
+	/**
+	* Returns the type of this picture. Must be one of the static constans defined in this class.
+	*
+	* @return type of this picture.
+	*/
+	public int getType(){
+		int type = LittleEndian.getShort(header, 0);
+		return type;
+	}
+}

src/scratchpad/src/org/apache/poi/hslf/usermodel/SlideShow.java

@@ -391,4 +391,11 @@ public class SlideShow
    * found in the slideshow
    */
   //public MetaSheet[] getMetaSheets() { return _msheets; }
+
+	/**
+	 * Returns all the pictures attached to the SlideShow
+	 */
+	public Picture[] getPictures() throws IOException {
+		return _hslfSlideShow.getPictures();
+	}
 }