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Apache FOP (Formatting Objects Processor) is the world's first print formatter driven by XSL formatting objects (XSL-FO) and the world's first output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output. Output formats currently supported include PDF, PCL, PS, AFP, TIFF, PNG, SVG, XML (area tree representation), Print, AWT and TXT. The primary output target is PDF.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

/* $Id: CTMHelper.java 679326 2008-07-24 09:35:34Z vhennebert $ */

package org.apache.fop.render.pdf;

import java.awt.geom.AffineTransform;

import org.apache.fop.area.CTM;
import org.apache.fop.pdf.PDFNumber;

/**
 * CTMHelper converts FOP transformation matrices to those
 * suitable for use by the PDFRenderer. The e and f elements
 * of the matrix will be divided by 1000 as FOP uses millipoints
 * as it's default user space and PDF uses points.
 *
 * @see org.apache.fop.area.CTM
 */
public final class CTMHelper {
    /**
     * Converts the sourceMatrix to a string for use in the PDFRenderer cm operations.
     * For example:
     * 
     *    org.apache.fop.area.CTM ctm =
     *          new org.apache.fop.area.CTM(1.0, 0.0, 0.0, 1.0, 1000.0, 1000.0);
     *    String pdfMatrix =  org.apache.fop.render.pdf.CTMHelper.toPDFString(ctm);
     * 
     * will return the string "1.0 0.0 0.0 1.0 1.0 1.0".
     *
     * @param sourceMatrix - The matrix to convert.
     *
     * @return  a space seperated string containing the matrix elements.
     */
    public static String toPDFString(CTM sourceMatrix) {
        if (null == sourceMatrix) {
            throw new NullPointerException("sourceMatrix must not be null");
        }

        final double[] matrix = toPDFArray(sourceMatrix);

        return constructPDFArray(matrix);
    }

    /**
     * Converts the AffineTransform instance to a string for use in the PDFRenderer
     * cm operations.
     *
     * @param transform The matrix to convert.
     * @param convertMillipoints Indicates that the matrix needs to be converted from millipoints
     *                           to points.
     * @return  a space seperated string containing the matrix elements.
     */
    public static String toPDFString(AffineTransform transform, boolean convertMillipoints) {
        if (null == transform) {
            throw new NullPointerException("transform must not be null");
        }

        final double[] matrix = new double[6];
        transform.getMatrix(matrix);
        if (convertMillipoints) {
            //Convert from millipoints to points
            matrix[4] /= 1000;
            matrix[5] /= 1000;
        }

        return constructPDFArray(matrix);
    }

    private static String constructPDFArray(double[] matrix) {
        return PDFNumber.doubleOut(matrix[0], 8) + " "
                + PDFNumber.doubleOut(matrix[1], 8) + " "
                + PDFNumber.doubleOut(matrix[2], 8) + " "
                + PDFNumber.doubleOut(matrix[3], 8) + " "
                + PDFNumber.doubleOut(matrix[4], 8) + " "
                + PDFNumber.doubleOut(matrix[5], 8);
    }

    /**
     * Creates a new CTM based in the sourceMatrix.
     * For example:
     * 
     *    org.apache.fop.area.CTM inCTM =
     *          new org.apache.fop.area.CTM(1.0, 0.0, 0.0, 1.0, 1000.0, 1000.0);
     *    org.apache.fop.area.CTM outCTM =
     *          org.apache.fop.render.pdf.CTMHelper.toPDFCTM(ctm);
     * 
     * will return a new CTM where a == 1.0, b == 0.0, c == 0.0, d == 1.0, e == 1.0 and f == 1.0.
     *
     * @param sourceMatrix - The matrix to convert.
     *
     * @return  a new converted matrix.
     */
    public static CTM toPDFCTM(CTM sourceMatrix) {
        if (null == sourceMatrix) {
            throw new NullPointerException("sourceMatrix must not be null");
        }

        final double[] matrix = toPDFArray(sourceMatrix);

        return new CTM(matrix[0], matrix[1], matrix[2], matrix[3],
                       matrix[4], matrix[5]);
    }

    /**
     * Creates an array of six doubles from the source CTM.
     * For example:
     * 
     *    org.apache.fop.area.CTM inCTM =
     *          new org.apache.fop.area.CTM(1.0, 0.0, 0.0, 1.0, 1000.0, 1000.0);
     *    double matrix[] = org.apache.fop.render.pdf.CTMHelper.toPDFArray(ctm);
     * 
     * will return a new array where matrix[0] == 1.0, matrix[1] == 0.0,
     * matrix[2] == 0.0, matrix[3] == 1.0,
     * matrix[4] == 1.0 and matrix[5] == 1.0.
     *
     * @param sourceMatrix - The matrix to convert.
     * @return  an array of doubles containing the converted matrix.
     */
    public static double[] toPDFArray(CTM sourceMatrix) {
        if (null == sourceMatrix) {
            throw new NullPointerException("sourceMatrix must not be null");
        }

        final double[] matrix = sourceMatrix.toArray();

        return new double[]{matrix[0], matrix[1], matrix[2], matrix[3],
                            matrix[4] / 1000.0, matrix[5] / 1000.0};
    }

}