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/*
 * Copyright 2009 by Kevin Day.
 *
 * 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) 1999-2008 by Bruno Lowagie.
 * All Rights Reserved.
 * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
 * are Copyright (C) 2000-2008 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.parser;

import com.lowagie.text.pdf.DocumentFont;

/**
 * Provides information and calculations needed by render listeners
 * to display/evaluate text render operations.
 * 


 * This is passed between the {@link PdfContentStreamProcessor} and 
 * {@link RenderListener} objects as text rendering operations are
 * discovered
 */
public class TextRenderInfo {
    private final String text;
    private final Matrix textToUserSpaceTransformMatrix;
    private final GraphicsState gs;
    
    /**
     * Creates a new TextRenderInfo object
     * @param text the text that should be displayed
     * @param gs the graphics state (note: at this time, this is not immutable, so don't cache it)
     * @param textMatrix the text matrix at the time of the render operation
     */
    TextRenderInfo(String text, GraphicsState gs, Matrix textMatrix) {
        this.text = text;
        this.textToUserSpaceTransformMatrix = textMatrix.multiply(gs.ctm);
        this.gs = gs;
    }
    
    /**
     * @return the text to render
     */
    public String getText(){ 
        return text; 
    }

    /**
     * @return the unscaled (i.e. in Text space) width of the text
     */
    public float getUnscaledWidth(){ 
        return getStringWidth(text); 
    }
    
    /**
     * @return a vector in User space representing the start point of the text
     */
    public Vector getStartPoint(){ 
        return new Vector(0, 0, 1).cross(textToUserSpaceTransformMatrix); 
    }
    
    /**
     * @return a vector in User space representing the end point of the text (i.e. the 
     * starting point of the text plus the width of the text, transformed by the applicable transformation matrices)
     */
    public Vector getEndPoint(){ 
        return new Vector(getUnscaledWidth(), 0, 1).cross(textToUserSpaceTransformMatrix); 
    }
    
    /**
     * @return The width, in user space units, of a single space character in the current font
     */
    public float getSingleSpaceWidth(){
        return new Vector(getUnscaledFontSpaceWidth(), 0, 1).cross(textToUserSpaceTransformMatrix).subtract(getStartPoint()).length();
    }
    
    /**
     * Calculates the width of a space character.  If the font does not define
     * a width for a standard space character \u0020, we also attempt to use
     * the width of \u00A0 (a non-breaking space in many fonts)
     * @return the width of a single space character in text space units
     */
    private float getUnscaledFontSpaceWidth(){
        char charToUse = ' ';
        if (gs.font.getWidth(charToUse) == 0)
            charToUse = '\u00A0';
        return getStringWidth(String.valueOf(charToUse));
    }
    
    /**
     * Gets the width of a String in text space units
     * @param string    the string that needs measuring
     * @return  the width of a String in text space units
     */
    private float getStringWidth(String string){
        DocumentFont font = gs.font;
        char[] chars = string.toCharArray();
        float totalWidth = 0;
        for (int i = 0; i < chars.length; i++) {
            float w = font.getWidth(chars[i]) / 1000.0f;
            float wordSpacing = chars[i] == 32 ? gs.wordSpacing : 0f;
            totalWidth += (w * gs.fontSize + gs.characterSpacing + wordSpacing) * gs.horizontalScaling;
        }
        
        return totalWidth;
    }    
}