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/*
 * Copyright (c) 2007, intarsys consulting GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - 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.
 *
 * - Neither the name of intarsys nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, 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.
 */
package de.intarsys.pdf.font;

import java.util.Iterator;

import de.intarsys.pdf.cos.COSArray;
import de.intarsys.pdf.cos.COSDictionary;
import de.intarsys.pdf.cos.COSName;
import de.intarsys.pdf.cos.COSNumber;
import de.intarsys.pdf.cos.COSObject;
import de.intarsys.pdf.encoding.Encoding;
import de.intarsys.pdf.encoding.GlyphNameMap;
import de.intarsys.pdf.encoding.MappedEncoding;

/**
 * An encoding defined as a delta to another base encoding.
 * 
 * 
 * 
 * 
 *   the encoding difference is defined in the form
 *   ...
 *   num name name name
 *   num name..
 *   ...
 * 
 * 
 * 
 * 
 * 
 * where num is the codepoint for the first glyph name in the list. The
 * following names are mapped to the codepoint of the predecessor + 1. Multiple
 * redefinition offsets can be defined.
 * 
 */
public class DifferenceEncoding extends Encoding {

	public static final COSName DK_Differences = COSName
			.constant("Differences");

	public static final COSName DK_BaseEncoding = COSName
			.constant("BaseEncoding");

	/**
	 * Create the difference encoding from the values defined in the
	 * dict.
	 * 
	 * @param dict
	 *            The dictionary defining the difference.
	 * @param font
	 *            The font defining the base encoding.
	 * 
	 * @return The difference encoding from the values defined in the
	 *         dict.
	 */
	public static Encoding create(COSDictionary dict, PDFont font) {
		DifferenceEncoding encoding = new DifferenceEncoding(dict);
		COSObject base = dict.get(DK_BaseEncoding);
		Encoding baseEncoding = null;
		if (base.isNull()) {
			baseEncoding = font.createDefaultEncoding();
		}
		if (base instanceof COSName) {
			try {
				baseEncoding = Encoding.createNamed((COSName) base);
			} catch (Exception e) {
				// found PDF where the base name was /NULL...
				baseEncoding = font.createDefaultEncoding();
			}
		}
		encoding.setBaseEncoding(baseEncoding);
		MappedEncoding differenceEncoding = new MappedEncoding();
		encoding.setDifferenceEncoding(differenceEncoding);

		COSArray differences = dict.get(DK_Differences).asArray();
		if (differences != null) {
			int start = -1;
			for (Iterator it = differences.iterator(); it.hasNext();) {
				COSObject element = (COSObject) it.next();
				if (element instanceof COSNumber) {
					start = ((COSNumber) element).intValue();
				}
				if (element instanceof COSName && (start > -1)) {
					String name = ((COSName) element).stringValue();
					differenceEncoding.addEncoding(start, name);
					start++;
				}
			}
		}
		return encoding;
	}

	// the dictionary object representing the encoding
	final private COSDictionary dict;

	// the base encoding
	private Encoding baseEncoding;

	// the difference declaration
	private MappedEncoding differenceEncoding;

	protected DifferenceEncoding(COSDictionary dict) {
		super();
		this.dict = dict;
	}

	/**
	 * Return the COSDictionary used to define the difference in the encoding.
	 * 
	 * @return Return the COSDictionary used to define the difference in the
	 *         encoding.
	 */
	protected COSDictionary cosGetDict() {
		return dict;
	}

	@Override
	public COSObject cosGetObject() {
		return cosGetDict();
	}

	/**
	 * Return the base encoding against which we defined the difference.
	 * 
	 * @return Return the base encoding against which we defined the difference.
	 */
	protected Encoding getBaseEncoding() {
		return baseEncoding;
	}

	@Override
	public int getDecoded(int codepoint) {
		int code = getDifferenceEncoding().getDecoded(codepoint);
		if (code == -1) {
			code = getBaseEncoding().getDecoded(codepoint);
		}
		return code;
	}

	@Override
	public int getDifferenceDecoded(int codePoint) {
		int code = getDifferenceEncoding().getDecoded(codePoint);
		if (code == -1) {
			return codePoint;
		}
		return code;
	}

	/**
	 * Get the {@link MappedEncoding} built from the differences dictionary.
	 * 
	 * @return The {@link MappedEncoding} built from the differences dictionary.
	 */
	protected MappedEncoding getDifferenceEncoding() {
		return differenceEncoding;
	}

	@Override
	public String getDifferenceGlyphName(int codePoint) {
		String name = getDifferenceEncoding().getGlyphName(codePoint);
		if ((name == null) || name.equals(GlyphNameMap.GLYPH_NOTDEF)) {
			return null;
		}
		return name;
	}

	@Override
	public int getEncoded(int character) {
		int code = getDifferenceEncoding().getEncoded(character);
		if (code == -1) {
			code = getBaseEncoding().getEncoded(character);
		}
		return code;
	}

	@Override
	public int getEncoded(java.lang.String name) {
		int code = getDifferenceEncoding().getEncoded(name);
		if (code == -1) {
			code = getBaseEncoding().getEncoded(name);
		}
		return code;
	}

	@Override
	public String getGlyphName(int codePoint) {
		String name = getDifferenceEncoding().getGlyphName(codePoint);
		if ((name == null) || name == GlyphNameMap.GLYPH_NOTDEF) {
			name = getBaseEncoding().getGlyphName(codePoint);
		}
		return name;
	}

	@Override
	public String getName() {
		return "DifferenceEncoding";
	}

	@Override
	public boolean isFontSpecificEncoding() {
		return getBaseEncoding().isFontSpecificEncoding();
	}

	/**
	 * Set the base encoding against which we defined the difference.
	 * 
	 * @param newBaseEncoding
	 *            The base encoding against which we defined the difference.
	 */
	private void setBaseEncoding(Encoding newBaseEncoding) {
		baseEncoding = newBaseEncoding;
	}

	/**
	 * Set the {@link MappedEncoding} decoded from the differences dictionary.
	 * 
	 * @param newDifferenceEncoding
	 *            The {@link MappedEncoding} decoded from the differences
	 *            dictionary.
	 */
	protected void setDifferenceEncoding(MappedEncoding newDifferenceEncoding) {
		differenceEncoding = newDifferenceEncoding;
	}
}