org.apache.poi.ss.util.ImageUtils Maven / Gradle / Ivy
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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
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http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.poi.ss.util;
import org.w3c.dom.NodeList;
import org.w3c.dom.Element;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.util.POILogger;
import org.apache.poi.util.POILogFactory;
import javax.imageio.ImageReader;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Iterator;
/**
* @author Yegor Kozlov
*/
public class ImageUtils {
private static final POILogger logger = POILogFactory.getLogger(ImageUtils.class);
public static final int PIXEL_DPI = 96;
/**
* Return the dimension of this image
*
* @param is the stream containing the image data
* @param type type of the picture: {@link org.apache.poi.ss.usermodel.Workbook#PICTURE_TYPE_JPEG},
* {@link org.apache.poi.ss.usermodel.Workbook#PICTURE_TYPE_PNG} or {@link org.apache.poi.ss.usermodel.Workbook#PICTURE_TYPE_DIB}
*
* @return image dimension in pixels
*/
public static Dimension getImageDimension(InputStream is, int type){
Dimension size = new Dimension();
switch (type){
//we can calculate the preferred size only for JPEG, PNG and BMP
//other formats like WMF, EMF and PICT are not supported in Java
case Workbook.PICTURE_TYPE_JPEG:
case Workbook.PICTURE_TYPE_PNG:
case Workbook.PICTURE_TYPE_DIB:
try {
//read the image using javax.imageio.*
ImageInputStream iis = ImageIO.createImageInputStream( is );
Iterator i = ImageIO.getImageReaders( iis );
ImageReader r = (ImageReader) i.next();
r.setInput( iis );
BufferedImage img = r.read(0);
int[] dpi = getResolution(r);
//if DPI is zero then assume standard 96 DPI
//since cannot divide by zero
if (dpi[0] == 0) dpi[0] = PIXEL_DPI;
if (dpi[1] == 0) dpi[1] = PIXEL_DPI;
size.width = img.getWidth()*PIXEL_DPI/dpi[0];
size.height = img.getHeight()*PIXEL_DPI/dpi[1];
r.dispose();
iis.close();
} catch (IOException e){
//silently return if ImageIO failed to read the image
logger.log(POILogger.WARN, e);
}
break;
default:
logger.log(POILogger.WARN, "Only JPEG, PNG and DIB pictures can be automatically sized");
}
return size;
}
/**
* The metadata of PNG and JPEG can contain the width of a pixel in millimeters.
* Return the the "effective" dpi calculated as 25.4/HorizontalPixelSize
* and 25.4/VerticalPixelSize. Where 25.4 is the number of mm in inch.
*
* @return array of two elements: {horisontalPdi, verticalDpi}.
* {96, 96} is the default.
*/
public static int[] getResolution(ImageReader r) throws IOException {
int hdpi=96, vdpi=96;
double mm2inch = 25.4;
NodeList lst;
Element node = (Element)r.getImageMetadata(0).getAsTree("javax_imageio_1.0");
lst = node.getElementsByTagName("HorizontalPixelSize");
if(lst != null && lst.getLength() == 1) hdpi = (int)(mm2inch/Float.parseFloat(((Element)lst.item(0)).getAttribute("value")));
lst = node.getElementsByTagName("VerticalPixelSize");
if(lst != null && lst.getLength() == 1) vdpi = (int)(mm2inch/Float.parseFloat(((Element)lst.item(0)).getAttribute("value")));
return new int[]{hdpi, vdpi};
}
}