truetypefontsubset.java

iText是一个能够快速产生PDF文件的java类库。iText的java类对于那些要产生包含文本

/*
 * $Id: TrueTypeFontSubSet.java 2366 2006-09-14 23:10:58Z xlv $
 * $Name$
 *
 * Copyright 2001, 2002 Paulo Soares
 *
 * The contents of this file are subject to the Mozilla Public License Version 1.1
 * (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the License.
 *
 * The Original Code is 'iText, a free JAVA-PDF library'.
 *
 * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
 * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
 * All Rights Reserved.
 * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
 * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
 *
 * Contributor(s): all the names of the contributors are added in the source code
 * where applicable.
 *
 * Alternatively, the contents of this file may be used under the terms of the
 * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
 * provisions of LGPL are applicable instead of those above.  If you wish to
 * allow use of your version of this file only under the terms of the LGPL
 * License and not to allow others to use your version of this file under
 * the MPL, indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by the LGPL.
 * If you do not delete the provisions above, a recipient may use your version
 * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the MPL as stated above or under the terms of the GNU
 * Library General Public License as published by the Free Software Foundation;
 * either version 2 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
 * details.
 *
 * If you didn't download this code from the following link, you should check if
 * you aren't using an obsolete version:
 * http://www.lowagie.com/iText/
 */

package com.lowagie.text.pdf;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;

import com.lowagie.text.DocumentException;
import com.lowagie.text.ExceptionConverter;

/** Subsets a True Type font by removing the unneeded glyphs from
 * the font.
 *
 * @author  Paulo Soares ([e-mail])
 */
class TrueTypeFontSubSet {
    static final String tableNamesSimple[] = {"cvt ", "fpgm", "glyf", "head",
        "hhea", "hmtx", "loca", "maxp", "prep"};
    static final String tableNamesCmap[] = {"cmap", "cvt ", "fpgm", "glyf", "head",
        "hhea", "hmtx", "loca", "maxp", "prep"};
    static final String tableNamesExtra[] = {"OS/2", "cmap", "cvt ", "fpgm", "glyf", "head",
        "hhea", "hmtx", "loca", "maxp", "name, prep"};
    static final int entrySelectors[] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4};
    static final int TABLE_CHECKSUM = 0;
    static final int TABLE_OFFSET = 1;
    static final int TABLE_LENGTH = 2;
    static final int HEAD_LOCA_FORMAT_OFFSET = 51;

    static final int ARG_1_AND_2_ARE_WORDS = 1;
    static final int WE_HAVE_A_SCALE = 8;
    static final int MORE_COMPONENTS = 32;
    static final int WE_HAVE_AN_X_AND_Y_SCALE = 64;
    static final int WE_HAVE_A_TWO_BY_TWO = 128;
    
    
    /** Contains the location of the several tables. The key is the name of
     * the table and the value is an <CODE>int[3]</CODE> where position 0
     * is the checksum, position 1 is the offset from the start of the file
     * and position 2 is the length of the table.
     */
    protected HashMap tableDirectory;
    /** The file in use.
     */
    protected RandomAccessFileOrArray rf;
    /** The file name.
     */
    protected String fileName;
    protected boolean includeCmap;
    protected boolean includeExtras;
    protected boolean locaShortTable;
    protected int locaTable[];
    protected HashMap glyphsUsed;
    protected ArrayList glyphsInList;
    protected int tableGlyphOffset;
    protected int newLocaTable[];
    protected byte newLocaTableOut[];
    protected byte newGlyfTable[];
    protected int glyfTableRealSize;
    protected int locaTableRealSize;
    protected byte outFont[];
    protected int fontPtr;
    protected int directoryOffset;

    /** Creates a new TrueTypeFontSubSet
     * @param directoryOffset The offset from the start of the file to the table directory
     * @param fileName the file name of the font
     * @param glyphsUsed the glyphs used
     * @param includeCmap <CODE>true</CODE> if the table cmap is to be included in the generated font
     */
    TrueTypeFontSubSet(String fileName, RandomAccessFileOrArray rf, HashMap glyphsUsed, int directoryOffset, boolean includeCmap, boolean includeExtras) {
        this.fileName = fileName;
        this.rf = rf;
        this.glyphsUsed = glyphsUsed;
        this.includeCmap = includeCmap;
        this.includeExtras = includeExtras;
        this.directoryOffset = directoryOffset;
        glyphsInList = new ArrayList(glyphsUsed.keySet());
    }
    
    /** Does the actual work of subsetting the font.
     * @throws IOException on error
     * @throws DocumentException on error
     * @return the subset font
     */    
    byte[] process() throws IOException, DocumentException {
        try {
            rf.reOpen();
            createTableDirectory();
            readLoca();
            flatGlyphs();
            createNewGlyphTables();
            locaTobytes();
            assembleFont();
            return outFont;
        }
        finally {
            try {
                rf.close();
            }
            catch (Exception e) {
                // empty on purpose
            }
        }
    }
    
    protected void assembleFont() throws IOException {
        int tableLocation[];
        int fullFontSize = 0;
        String tableNames[];
        if (includeExtras)
            tableNames = tableNamesExtra;
        else {
            if (includeCmap)
                tableNames = tableNamesCmap;
            else
                tableNames = tableNamesSimple;
        }
        int tablesUsed = 2;
        int len = 0;
        for (int k = 0; k < tableNames.length; ++k) {
            String name = tableNames[k];
            if (name.equals("glyf") || name.equals("loca"))
                continue;
            tableLocation = (int[])tableDirectory.get(name);
            if (tableLocation == null)
                continue;
            ++tablesUsed;
            fullFontSize += (tableLocation[TABLE_LENGTH] + 3) & (~3);
        }
        fullFontSize += newLocaTableOut.length;
        fullFontSize += newGlyfTable.length;
        int ref = 16 * tablesUsed + 12;
        fullFontSize += ref;
        outFont = new byte[fullFontSize];
        fontPtr = 0;
        writeFontInt(0x00010000);
        writeFontShort(tablesUsed);
        int selector = entrySelectors[tablesUsed];
        writeFontShort((1 << selector) * 16);
        writeFontShort(selector);
        writeFontShort((tablesUsed - (1 << selector)) * 16);
        for (int k = 0; k < tableNames.length; ++k) {
            String name = tableNames[k];
            tableLocation = (int[])tableDirectory.get(name);
            if (tableLocation == null)
                continue;
            writeFontString(name);
            if (name.equals("glyf")) {
                writeFontInt(calculateChecksum(newGlyfTable));
                len = glyfTableRealSize;
            }
            else if (name.equals("loca")) {
                writeFontInt(calculateChecksum(newLocaTableOut));
                len = locaTableRealSize;
            }
            else {
                writeFontInt(tableLocation[TABLE_CHECKSUM]);
                len = tableLocation[TABLE_LENGTH];
            }
            writeFontInt(ref);
            writeFontInt(len);
            ref += (len + 3) & (~3);
        }
        for (int k = 0; k < tableNames.length; ++k) {
            String name = tableNames[k];