DictionaryEncoding.java

package com.tom_roush.pdfbox.pdmodel.font.encoding;

import com.tom_roush.pdfbox.cos.COSArray;
import com.tom_roush.pdfbox.cos.COSBase;
import com.tom_roush.pdfbox.cos.COSDictionary;
import com.tom_roush.pdfbox.cos.COSName;
import com.tom_roush.pdfbox.cos.COSNumber;

import java.util.HashMap;
import java.util.Map;

/**
 * This will perform the encoding from a dictionary.
 *
 * @author Ben Litchfield
 */
public class DictionaryEncoding extends Encoding
{
	private final COSDictionary encoding;
	private final Encoding baseEncoding;
	private final Map<Integer, String> differences = new HashMap<Integer, String>();

	/**
	 * Creates a new DictionaryEncoding for embedding.
	 */
	public DictionaryEncoding(COSName baseEncoding, COSArray differences)
	{
		encoding = new COSDictionary();
		encoding.setItem(COSName.NAME, COSName.ENCODING);
		encoding.setItem(COSName.DIFFERENCES, differences);
		if (baseEncoding != COSName.STANDARD_ENCODING)
		{
			encoding.setItem(COSName.BASE_ENCODING, baseEncoding);
			this.baseEncoding = Encoding.getInstance(baseEncoding);
		}
		else
		{
			this.baseEncoding = Encoding.getInstance(baseEncoding);
		}

		if (this.baseEncoding == null)
		{
			throw new IllegalArgumentException("Invalid encoding: " + baseEncoding);
		}

        codeToName.putAll(this.baseEncoding.codeToName);
        names.addAll(this.baseEncoding.names);
        applyDifferences();
    }

	/**
	 * Creates a new DictionaryEncoding for a Type 3 font from a PDF.
	 *
	 * @param fontEncoding The Type 3 encoding dictionary.
	 */
	public DictionaryEncoding(COSDictionary fontEncoding)
	{
		encoding = fontEncoding;
		baseEncoding = null;
		applyDifferences();
	}

	/**
	 * Creates a new DictionaryEncoding from a PDF.
	 *
	 * @param fontEncoding The encoding dictionary.
	 * @param isNonSymbolic True if the font is non-symbolic. False for Type 3 fonts.
	 * @param builtIn The font's built-in encoding. Null for Type 3 fonts.
	 */
	public DictionaryEncoding(COSDictionary fontEncoding, boolean isNonSymbolic, Encoding builtIn)
	{
		encoding = fontEncoding;

		Encoding base = null;
		if (encoding.containsKey(COSName.BASE_ENCODING))
		{
			COSName name = encoding.getCOSName(COSName.BASE_ENCODING);
			base = Encoding.getInstance(name); // may be null
		}

		if (base == null)
		{
			if (isNonSymbolic)
			{
				// Otherwise, for a nonsymbolic font, it is StandardEncoding
				base = StandardEncoding.INSTANCE;
			}
			else
			{
				// and for a symbolic font, it is the font's built-in encoding.
				if (builtIn != null)
				{
					base = builtIn;
				}
				else
				{
					throw new IllegalArgumentException("Symbolic fonts must have a built-in " +
						"encoding");
				}
			}
		}
		baseEncoding = base;

		codeToName.putAll(baseEncoding.codeToName);
		names.addAll(baseEncoding.names);
		applyDifferences();
	}

	private void applyDifferences()
	{
		// now replace with the differences
		COSArray differences = (COSArray) encoding.getDictionaryObject(COSName.DIFFERENCES);
		int currentIndex = -1;
		for (int i = 0; differences != null && i < differences.size(); i++)
		{
			COSBase next = differences.getObject(i);
			if (next instanceof COSNumber)
			{
				currentIndex = ((COSNumber) next).intValue();
			}
			else if (next instanceof COSName)
			{
				COSName name = (COSName) next;
				add(currentIndex, name.getName());
				this.differences.put(currentIndex, name.getName());
				currentIndex++;
			}
		}
	}

	/**
	 * Returns the base encoding. Will be null for Type 3 fonts.
	 */
	public Encoding getBaseEncoding()
	{
		return baseEncoding;
	}

	/**
	 * Returns the Differences array.
	 */
	public Map<Integer, String> getDifferences()
	{
		return differences;
	}

	/**
	 * Convert this standard java object to a COS object.
	 *
	 * @return The cos object that matches this Java object.
	 */
	public COSBase getCOSObject()
	{
		return encoding;
	}
}