pdfont.java

非常有用的操作pdf文件的java源码

        float retval = 0;
        FontMetric metric = getAFM();
        if( metric != null )
        {
            Encoding encoding = getEncoding();
            COSName characterName = encoding.getName( code );
            retval = metric.getCharacterWidth( characterName.getName() );
        }
        return retval;
    }

    /**
     * This will attempt to get the average font width from an AFM file.
     *
     * @return The average font width from the AFM file.
     *
     * @throws IOException if we cannot find the width.
     */
    protected float getAverageFontWidthFromAFMFile() throws IOException
    {
        float retval = 0;
        FontMetric metric = getAFM();
        if( metric != null )
        {
            retval = metric.getAverageCharacterWidth();
        }
        return retval;
    }

    /**
     * This will get an AFM object if one exists.
     *
     * @return The afm object from the name.
     *
     * @throws IOException If there is an error getting the AFM object.
     */
    protected FontMetric getAFM() throws IOException
    {
        COSName name = (COSName)font.getDictionaryObject( COSName.BASE_FONT );
        FontMetric result = null;
        if( name != null )
        {
            result = (FontMetric)afmObjects.get( name );
            if( result == null )
            {
                String resource = (String)afmResources.get( name );
                if( resource == null )
                {
                    //ok for now
                    //throw new IOException( "Unknown AFM font '" + name.getName() + "'" );
                }
                else
                {
                    InputStream afmStream = ResourceLoader.loadResource( resource );
                    if( afmStream == null )
                    {
                        throw new IOException( "Can't handle font width:" + resource );
                    }
                    AFMParser parser = new AFMParser( afmStream );
                    parser.parse();
                    result = parser.getResult();
                    afmObjects.put( name, result );
                }
            }
        }
        return result;
    }

    /**
     * This will perform the encoding of a character if needed.
     *
     * @param c The character to encode.
     * @param offset The offset into the array to get the data
     * @param length The number of bytes to read.
     *
     * @return The value of the encoded character.
     *
     * @throws IOException If there is an error during the encoding.
     */
    public String encode( byte[] c, int offset, int length ) throws IOException
    {
        String retval = null;
        COSName fontSubtype = (COSName)font.getDictionaryObject( COSName.SUBTYPE );
        String fontSubtypeName = fontSubtype.getName();
        if( fontSubtypeName.equals( "Type0" ) ||
            fontSubtypeName.equals( "Type1" ) ||
            fontSubtypeName.equals( "TrueType" ))
        {
            if( cmap == null )
            {
                if( font.getDictionaryObject( COSName.TO_UNICODE ) != null )
                {
                    COSStream toUnicode = (COSStream)font.getDictionaryObject( COSName.TO_UNICODE );
                    if( toUnicode != null )
                    {
                        parseCmap( toUnicode.getUnfilteredStream(), null );
                    }
                }
                else
                {
                    COSBase encoding = font.getDictionaryObject( COSName.ENCODING );
                    if( encoding instanceof COSStream )
                    {
                        COSStream encodingStream = (COSStream)encoding;
                        parseCmap( encodingStream.getUnfilteredStream(), null );
                    }
                    else if( fontSubtypeName.equals( "Type0" ) &&
                             encoding instanceof COSName )
                    {
                        COSName encodingName = (COSName)encoding;
                        cmap = (CMap)cmapObjects.get( encodingName );
                        if( cmap != null )
                        {
                            cmap = (CMap)cmapObjects.get( encodingName );
                        }
                        else
                        {
                            String cmapName = encodingName.getName();
                            cmapName = performCMAPSubstitution( cmapName );
                            String resourceName = "Resources/cmap/" + cmapName;
                            parseCmap( ResourceLoader.loadResource( resourceName ), encodingName );
                            if( cmap == null && !encodingName.getName().equals( COSName.IDENTITY_H.getName() ) )
                            {
                                throw new IOException( "Error: Could not find predefined " +
                                "CMAP file for '" + encodingName.getName() + "'" );
                            }
                        }
                    }
                    else if( encoding instanceof COSName ||
                             encoding instanceof COSDictionary )
                    {
                        Encoding currentFontEncoding = getEncoding();
                        if( currentFontEncoding != null )
                        {
                            retval = currentFontEncoding.getCharacter( getCodeFromArray( c, offset, length ) );
                        }
                    }
                    else
                    {
                        COSDictionary fontDescriptor =
                            (COSDictionary)font.getDictionaryObject( COSName.FONT_DESC );
                        if( fontSubtypeName.equals( "TrueType" ) &&
                            fontDescriptor != null &&
                            (fontDescriptor.getDictionaryObject( COSName.FONT_FILE )!= null ||
                             fontDescriptor.getDictionaryObject( COSName.FONT_FILE2 ) != null ||
                             fontDescriptor.getDictionaryObject( COSName.FONT_FILE3 ) != null ) )
                        {
                            //If we are using an embedded font then there is not much we can do besides
                            //return the same character codes.
                            //retval = new String( c,offset, length );
                            retval = getStringFromArray( c, offset, length );
                        }
                        else
                        {
                            //this case will be handled below after checking the cmap
                        }
                    }
                }


            }
        }
        if( retval == null && cmap != null )
        {
            retval = cmap.lookup( c, offset, length );
        }
        //if we havn't found a value yet and 
        //we are still on the first byte and
        //there is no cmap or the cmap does not have 2 byte mappings then try to encode
        //using fallback methods.
        if( retval == null && 
            length == 1 && 
            (cmap == null || !cmap.hasTwoByteMappings()))
        {
            Encoding encoding = getEncoding();
            if( encoding != null )
            {
                retval = encoding.getCharacter( getCodeFromArray( c, offset, length ) );
            }
            if( retval == null )
            {
                retval = getStringFromArray( c, offset, length );
            }
        }
        return retval;
    }
    
    private static final String[] SINGLE_CHAR_STRING = new String[256];
    private static final String[][] DOUBLE_CHAR_STRING = new String[256][256];
    static
    {
        for( int i=0; i<256; i++ )
        {
            SINGLE_CHAR_STRING[i] = new String( new byte[] {(byte)i} );
            for( int j=0; j<256; j++ )
            {
                DOUBLE_CHAR_STRING[i][j] = new String( new byte[] {(byte)i, (byte)j} );
            }
        }
    }
    
    private static String getStringFromArray( byte[] c, int offset, int length ) throws IOException
    {
        String retval = null;
        if( length == 1 )
        {
            retval = SINGLE_CHAR_STRING[(c[offset]+256)%256];
        }
        else if( length == 2 )
        {
            retval = DOUBLE_CHAR_STRING[(c[offset]+256)%256][(c[offset+1]+256)%256];
        }
        else
        {
            throw new IOException( "Error:Unknown character length:" + length );
        }
        return retval;
    }

    /**
     * Some cmap names are synonyms for other CMAPs.  If that is the case
     * then this method will perform that substitution.
     *
     * @param cmapName The name of the cmap to attempt to look up.
     *
     * @return Either the original name or the substituted name.
     */
    private String performCMAPSubstitution( String cmapName )
    {
        String retval = (String)cmapSubstitutions.get( cmapName );
        if( retval == null )
        {
            //if there is no substitution then just return the same value.
            retval = cmapName;
        }
        return retval;
    }

    private void parseCmap( InputStream cmapStream, COSName encodingName ) throws IOException
    {
        if( cmapStream != null )
        {
            CMapParser parser = new CMapParser();
            cmap = parser.parse( cmapStream );
            if( encodingName != null )
            {
                cmapObjects.put( encodingName, cmap );
            }
        }
    }
    
    /**
     * The will set the encoding for this font.
     * 
     * @param enc The font encoding.
     */
    public void setEncoding( Encoding enc )
    {
        font.setItem( COSName.ENCODING, enc );
        fontEncoding = enc;
    }

    /**
     * This will get or create the encoder.
     *
     * modified by Christophe Huault : DGBS Strasbourg [e-mail] october 2004
     *
     * @return The encoding to use.
     *
     * @throws IOException If there is an error getting the encoding.
     */
    public Encoding getEncoding() throws IOException
    {
        EncodingManager manager = new EncodingManager();
        if( fontEncoding == null )
        {
            COSBase encoding = font.getDictionaryObject( COSName.ENCODING );
            if( encoding == null )
            {
                FontMetric metric = getAFM();
                if( metric != null )
                {
                    fontEncoding = new AFMEncoding( metric );
                }
                if( fontEncoding == null )
                {
                    fontEncoding = manager.getStandardEncoding();
                }
            }
            /**
             * Si la cl