multicolumntext.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: MultiColumnText.java 2441 2006-10-27 17:24:01Z xlv $
 * $Name$
 *
 * Copyright 2004 Steve Appling
 *
 * 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) 1999-2005 by Bruno Lowagie.
 * All Rights Reserved.
 * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
 * are Copyright (C) 2000-2005 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.util.ArrayList;

import com.lowagie.text.Chunk;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Element;
import com.lowagie.text.ElementListener;
import com.lowagie.text.Phrase;
import com.lowagie.text.Rectangle;

/**
 * Formats content into one or more columns bounded by a
 * rectangle.  The columns may be simple rectangles or
 * more complicated shapes. Add all of the columns before
 * adding content. Column continuation is supported. A MultiColumnText object may be added to
 * a document using <CODE>Document.add</CODE>.
 * @author Steve Appling
 */
public class MultiColumnText implements Element {

    /** special constant for automatic calculation of height */
    public static final float AUTOMATIC = -1f;

    /**
     * total desiredHeight of columns.  If <CODE>AUTOMATIC</CODE>, this means fill pages until done.
     * This may be larger than one page
     */
    private float desiredHeight;

    /**
     * total height of element written out so far
     */
    private float totalHeight;

    /**
     * true if all the text could not be written out due to height restriction
     */
    private boolean overflow;

    /**
     * Top of the columns - y position on starting page.
     * If <CODE>AUTOMATIC</CODE>, it means current y position when added to document
     */
    private float top;

    /**
     * used to store the y position of the bottom of the page
     */
    private float pageBottom;

    /**
     * ColumnText object used to do all the real work.  This same object is used for all columns
     */
    private ColumnText columnText;

    /**
     * Array of <CODE>ColumnDef</CODE> objects used to define the columns
     */
    private ArrayList columnDefs;

    /**
     * true if all columns are simple (rectangular)
     */
    private boolean simple = true;

    private int currentColumn = 0;
    
    private float nextY = AUTOMATIC;
    
    private boolean columnsRightToLeft = false;
    
    private PdfDocument document;
    /**
     * Default constructor.  Sets height to <CODE>AUTOMATIC</CODE>.
     * Columns will repeat on each page as necessary to accomodate content length.
     */
    public MultiColumnText() {
        this(AUTOMATIC);
    }

    /**
     * Construct a MultiColumnText container of the specified height.
     * If height is <CODE>AUTOMATIC</CODE>, fill complete pages until done.
     * If a specific height is used, it may span one or more pages.
     *
     * @param height
     */
    public MultiColumnText(float height) {
        columnDefs = new ArrayList();
        desiredHeight = height;
        top = AUTOMATIC;
        // canvas will be set later
        columnText = new ColumnText(null);
        totalHeight = 0f;
    }

    /**
     * Construct a MultiColumnText container of the specified height
     * starting at the specified Y position.
     *
     * @param height
     * @param top
     */
    public MultiColumnText(float top, float height) {
        columnDefs = new ArrayList();
        desiredHeight = height;
        this.top = top;
        nextY = top;
        // canvas will be set later
        columnText = new ColumnText(null);
        totalHeight = 0f;
    }
    
    /**
     * Indicates that all of the text did not fit in the
     * specified height. Note that isOverflow will return
     * false before the MultiColumnText object has been
     * added to the document.  It will always be false if
     * the height is AUTOMATIC.
     *
     * @return true if there is still space left in the column
     */
    public boolean isOverflow() {
        return overflow;
    }

    /**
     * Copy the parameters from the specified ColumnText to use
     * when rendering.  Parameters like <CODE>setArabicOptions</CODE>
     * must be set in this way.
     *
     * @param sourceColumn
     */
    public void useColumnParams(ColumnText sourceColumn) {
        // note that canvas will be overwritten later
        columnText.setSimpleVars(sourceColumn);
    }

    /**
     * Add a new column.  The parameters are limits for each column
     * wall in the format of a sequence of points (x1,y1,x2,y2,...).
     *
     * @param left  limits for left column
     * @param right limits for right column
     */
    public void addColumn(float[] left, float[] right) {
        ColumnDef nextDef = new ColumnDef(left, right);
        simple = nextDef.isSimple();
        columnDefs.add(nextDef);
    }

    /**
     * Add a simple rectangular column with specified left
     * and right x position boundaries.
     *
     * @param left  left boundary
     * @param right right boundary
     */
    public void addSimpleColumn(float left, float right) {
        ColumnDef newCol = new ColumnDef(left, right);
        columnDefs.add(newCol);
    }

    /**
     * Add the specified number of evenly spaced rectangular columns.
     * Columns will be seperated by the specified gutterWidth.
     *
     * @param left        left boundary of first column
     * @param right       right boundary of last column
     * @param gutterWidth width of gutter spacing between columns
     * @param numColumns  number of columns to add
     */
    public void addRegularColumns(float left, float right, float gutterWidth, int numColumns) {
        float currX = left;
        float width = right - left;
        float colWidth = (width - (gutterWidth * (numColumns - 1))) / numColumns;
        for (int i = 0; i < numColumns; i++) {
            addSimpleColumn(currX, currX + colWidth);
            currX += colWidth + gutterWidth;
        }
    }

    /**
     * Add an element to be rendered in a column.
     * Note that you can only add a <CODE>Phrase</CODE>
     * or a <CODE>Chunk</CODE> if the columns are
     * not all simple.  This is an underlying restriction in
     * {@link com.lowagie.text.pdf.ColumnText}
     *
     * @param element element to add
     * @throws DocumentException if element can't be added
     */
    public void addElement(Element element) throws DocumentException {
        if (simple) {
            columnText.addElement(element);
        } else if (element instanceof Phrase) {
            columnText.addText((Phrase) element);
        } else if (element instanceof Chunk) {
            columnText.addText((Chunk) element);
        } else {
            throw new DocumentException("Can't add " + element.getClass() + " to MultiColumnText with complex columns");
        }
    }


    /**
     * Write out the columns.  After writing, use
     * {@link #isOverflow()} to see if all text was written.
     * @param canvas PdfContentByte to write with
     * @param document document to write to (only used to get page limit info)
     * @param documentY starting y position to begin writing at
     * @return the current height (y position) after writing the columns
     * @throws DocumentException on error
     */
    public float write(PdfContentByte canvas, PdfDocument document, float documentY) throws DocumentException {
        this.document = document;
        columnText.setCanvas(canvas);
        if (columnDefs.isEmpty()) {
            throw new DocumentException("MultiColumnText has no columns");
        }
        overflow = false;
        pageBottom = document.bottom();
        float currentHeight = 0;
        boolean done = false;
        try {
            while (!done) {
                if (nextY == AUTOMATIC) {
                    nextY = document.getVerticalPosition(true); // RS - 07/07/2005 - - Get current doc writing position for top of columns on new page.
                }
                if (top == AUTOMATIC) {
                    top = document.getVerticalPosition(true); // RS - 07/07/2005 - Get current doc writing position for top of columns on new page.
                }

                ColumnDef currentDef = (ColumnDef) columnDefs.get(getCurrentColumn());
                columnText.setYLine(top);

                float[] left = currentDef.resolvePositions(Rectangle.LEFT);
                float[] right = currentDef.resolvePositions(Rectangle.RIGHT);
                if (document.isMarginMirroring() && document.getPageNumber() % 2 == 0){
                    float delta = document.rightMargin() - document.left();