dib.java

来自「EXCEL read and write」· Java 代码 · 共 83 行

/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   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
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */
package org.apache.poi.hslf.blip;

import org.apache.poi.hslf.model.Picture;
import org.apache.poi.util.LittleEndian;

import java.io.IOException;

/**
 * Represents a DIB picture data in a PPT file
 * 
 * @author Yegor Kozlov
 */
public class DIB extends Bitmap {
    /**
     * Size of the BITMAPFILEHEADER structure preceding the actual DIB bytes
     */
    public static final int HEADER_SIZE = 14;

    /**
     * @return type of  this picture
     * @see  org.apache.poi.hslf.model.Picture#DIB
     */
    public int getType(){
        return Picture.DIB;
    }

    /**
     * DIB signature is <code>0x7A80</code>
     *
     * @return DIB signature (<code>0x7A80</code>)
     */
    public int getSignature(){
        return 0x7A80;
    }

    public byte[] getData(){
        byte[] data = super.getData();

        // bitmap file-header, corresponds to a
        // Windows  BITMAPFILEHEADER structure
        // (For more information, consult the Windows API Programmer's reference )
        byte[] header = new byte[HEADER_SIZE];
        //Specifies the file type. It must be set to the signature word BM (0x4D42) to indicate bitmap.
        LittleEndian.putInt(header, 0, 0x4D42);
        //Specifies the size, in bytes, of the bitmap file.
        LittleEndian.putInt(header, 2, data.length); //DIB length including the header
        //Reserved; set to zero
        LittleEndian.putInt(header, 6, 0);
        //the offset, in bytes, from the header to the bitmap bits (looks like it is always 2)
        LittleEndian.putInt(header, 10, 2);

        //DIB data is the header + dib bytes
        byte[] dib = new byte[header.length + data.length];
        System.arraycopy(header, 0, dib, 0, header.length);
        System.arraycopy(data, 0, dib, header.length, data.length);

        return dib;
    }

    public void setData(byte[] data) throws IOException {
        //cut off the bitmap file-header
        byte[] dib = new byte[data.length-HEADER_SIZE];
        System.arraycopy(data, HEADER_SIZE, dib, 0, dib.length);
        super.setData(dib);
    }
}