155 lines
6.1 KiB
Java
155 lines
6.1 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.sl.image;
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import java.awt.Dimension;
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import java.awt.Rectangle;
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import java.io.IOException;
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import java.io.OutputStream;
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import org.apache.poi.util.Internal;
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import org.apache.poi.util.LittleEndian;
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import org.apache.poi.util.POILogFactory;
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import org.apache.poi.util.POILogger;
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import org.apache.poi.util.Units;
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/**
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* Aldus Placeable Metafile header - 22 byte structure before WMF data.
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* <ul>
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* <li>int Key; Magic number (always 9AC6CDD7h)
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* <li>short Handle; Metafile HANDLE number (always 0)
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* <li>short Left; Left coordinate in metafile units
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* <li>short Top; Top coordinate in metafile units
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* <li>short Right; Right coordinate in metafile units
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* <li>short Bottom; Bottom coordinate in metafile units
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* <li>short Inch; Number of metafile units per inch
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* <li>int Reserved; Reserved (always 0)
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* <li>short Checksum; Checksum value for previous 10 shorts
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* </ul>
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*/
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@Internal
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public class ImageHeaderWMF {
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public static final int APMHEADER_KEY = 0x9AC6CDD7;
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private static POILogger LOG = POILogFactory.getLogger(ImageHeaderWMF.class);
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@SuppressWarnings("unused")
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private final int handle;
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private final int left, top, right, bottom;
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/**
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* The number of logical units per inch used to represent the image.
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* This value can be used to scale an image. By convention, an image is
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* considered to be recorded at 1440 logical units (twips) per inch.
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* Thus, a value of 720 specifies that the image SHOULD be rendered at
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* twice its normal size, and a value of 2880 specifies that the image
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* SHOULD be rendered at half its normal size.
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*/
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private final int inch;
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@SuppressWarnings("unused")
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private final int reserved;
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private int checksum;
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public ImageHeaderWMF(Rectangle dim) {
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handle = 0;
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left = dim.x;
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top = dim.y;
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right = dim.x + dim.width;
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bottom = dim.y + dim.height;
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inch = Units.POINT_DPI; //default resolution is 72 dpi
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reserved = 0;
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}
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public ImageHeaderWMF(byte[] data, int pos) {
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int key = LittleEndian.getInt(data, pos); pos += LittleEndian.INT_SIZE; //header key
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if (key != APMHEADER_KEY) {
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LOG.log(POILogger.WARN, "WMF file doesn't contain a placeable header - ignore parsing");
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handle = 0;
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left = 0;
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top = 0;
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right = 200;
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bottom = 200;
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inch = Units.POINT_DPI; //default resolution is 72 dpi
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reserved = 0;
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return;
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}
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handle = LittleEndian.getUShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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left = LittleEndian.getShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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top = LittleEndian.getShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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right = LittleEndian.getShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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bottom = LittleEndian.getShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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inch = LittleEndian.getUShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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reserved = LittleEndian.getInt(data, pos); pos += LittleEndian.INT_SIZE;
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checksum = LittleEndian.getShort(data, pos); pos += LittleEndian.SHORT_SIZE;
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if (checksum != getChecksum()){
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LOG.log(POILogger.WARN, "WMF checksum does not match the header data");
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}
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}
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/**
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* Returns a checksum value for the previous 10 shorts in the header.
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* The checksum is calculated by XORing each short value to an initial value of 0:
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*/
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public int getChecksum(){
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int cs = 0;
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cs ^= (APMHEADER_KEY & 0x0000FFFF);
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cs ^= ((APMHEADER_KEY & 0xFFFF0000) >> 16);
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cs ^= left;
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cs ^= top;
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cs ^= right;
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cs ^= bottom;
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cs ^= inch;
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return cs;
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}
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public void write(OutputStream out) throws IOException {
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byte[] header = new byte[22];
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int pos = 0;
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LittleEndian.putInt(header, pos, APMHEADER_KEY); pos += LittleEndian.INT_SIZE; //header key
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LittleEndian.putUShort(header, pos, 0); pos += LittleEndian.SHORT_SIZE; //hmf
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LittleEndian.putUShort(header, pos, left); pos += LittleEndian.SHORT_SIZE; //left
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LittleEndian.putUShort(header, pos, top); pos += LittleEndian.SHORT_SIZE; //top
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LittleEndian.putUShort(header, pos, right); pos += LittleEndian.SHORT_SIZE; //right
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LittleEndian.putUShort(header, pos, bottom); pos += LittleEndian.SHORT_SIZE; //bottom
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LittleEndian.putUShort(header, pos, inch); pos += LittleEndian.SHORT_SIZE; //inch
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LittleEndian.putInt(header, pos, 0); pos += LittleEndian.INT_SIZE; //reserved
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checksum = getChecksum();
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LittleEndian.putUShort(header, pos, checksum);
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out.write(header);
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}
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public Dimension getSize() {
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//coefficient to translate from WMF dpi to 72dpi
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double coeff = ((double)Units.POINT_DPI)/inch;
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return new Dimension((int)Math.round((right-left)*coeff), (int)Math.round((bottom-top)*coeff));
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}
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public Rectangle getBounds() {
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return new Rectangle(left, top, right-left, bottom-top);
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}
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public int getLength(){
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return 22;
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}
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}
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