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This is the PDF generator package of NervalReports (a lightweight report creation library), used to generate a report directly to a .pdf file.
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/** This file is part of nervalreports.
 *
 * nervalreports is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * nervalreports 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with nervalreports.  If not, see . */
package net.sf.nervalreports.generators;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDType0Font;

import net.sf.nervalreports.core.ReportGenerationException;

/** Information about a font for PDF generator use.
 * @author farrer */
public class PDFFontInfo {
	private final PDFont font;
	private final boolean defaultFont;
	private final Map codeToWidthMap;
	
	/** Constructor for default PDF font usage.
	 * @param font default PDF font. */
	PDFFontInfo(PDFont font) {
		this.font = font;
		this.defaultFont = true;
		this.codeToWidthMap = new HashMap();
	}
	
	/** Constructor, for .ttf font usage.
	 * @param document document where the font will be used.
	 * @param font {@link InputStream} for the font file.
	 * @throws ReportGenerationException in case of font load error. */
	public PDFFontInfo(PDDocument document, InputStream font) throws ReportGenerationException {
		try {
			this.font = PDType0Font.load(document, font);
			this.defaultFont = false;
			this.codeToWidthMap = new HashMap();
		} catch (IOException e) {
			throw new ReportGenerationException(e);
		}
	}
	
	/** @return the {@link PDFont} of this font. */
	PDFont getFont() {
		return font;
	}
	
	/** @return if the font is a default PDF font (true) or loaded .ttf one (false). */
	boolean isDefaultFont() {
		return defaultFont;
	}
	
	/** Calculate the LowerLeft Y coordinate of the font at an specific font size.
	 * @param size font size to use.
	 * @return calculated LowerLeft Y.
	 * @throws IOException in case of failure retrieving font information. */
	float getLowerLeftY(int size) throws IOException {
		return convertValueToScale(font.getBoundingBox().getLowerLeftY(), size);
	}
	
	/** Calculate the UpperRight Y coordinate of the font at an specific font size.
	 * @param size font size to use.
	 * @return calculated UpperRight Y.
	 * @throws IOException in case of failure retrieving font information. */
	float getUpperRightY(int size) throws IOException {
		return convertValueToScale(font.getBoundingBox().getUpperRightY(), size);
	}
	
	/** Calculate current ascend for a given font size.
	 * @param size font size to use.
	 * @return ascend value for the font size. */
	float getAscend(int size) {
		return convertValueToScale(font.getFontDescriptor().getAscent(), size);
	}
	
	/** Calculate current descend for a given font size.
	 * @param size font size to use.
	 * @return descend value for the font size. */
	float getDescend(int size) {
		return convertValueToScale(font.getFontDescriptor().getDescent(), size);
	}
	
	/** Calculate the height for a given font size.
	 * @param size font size to get its height.
	 * @return calculated height for this font size. 
	 * @throws IOException in case of failure retrieving font information. */
	float getHeight(int size) throws IOException {
		return getUpperRightY(size) - getLowerLeftY(size);
	}
	
	/** Calculate the space width of the font.
	 * @param size space width.
	 * @return width of the space. 
	 * @throws IOException in case of error retrieving. */
	float getSpaceWidth(int size) throws IOException {
		Float spaceWidth = codeToWidthMap.get(32);
        if(spaceWidth == null) {
        	/* Not yet calculated, let's get it, and cache it. */
        	spaceWidth = font.getWidthFromFont(32);
        	if(!isDefaultFont()) {
        		//XXX adjust, as seems that the space got from font and its rendered value are different.
        		spaceWidth *= 0.6f;
        	}
        	codeToWidthMap.put(32, spaceWidth);
        }
        
        return convertValueToScale(spaceWidth, size);
	}
	
	/** Calculate the width necessary to render a string with a defined font size.
	 * @param size size of the font.
	 * @param str {@link String} to render.
	 * @return needed width.
	 * @throws IOException in case of missing element for calculating. */
	float getStringWidth(int size, String str) throws IOException {
		
		/* Convert to a byte array for parsing it. */
		byte[] bytes = font.encode(str);
        ByteArrayInputStream in = new ByteArrayInputStream(bytes);
        
        float width = 0;
        while(in.available() > 0) {
        	
        	/* Get next Unicode glyph */
            int code = font.readCode(in);
            
            /* Check if it is already on map (cached) */
            Float charWidth = codeToWidthMap.get(code);
            if(charWidth != null) {
                width += charWidth;
            } else {
            	/* Not yet calculated, let's get it, and cache it. */
            	charWidth = font.getWidthFromFont(code);
            	codeToWidthMap.put(code, charWidth);
            	width += charWidth;
            }
        }
		
		return convertValueToScale(width, size);
	}
	
	/** Convert from UNITS to font size.
	 * @param value value to convert.
	 * @param size size of the font (in pts).
	 * @return converted value. */
	private float convertValueToScale(float value, int size) {
		return (value / 1000) * size;
	}
}