engine/src/blender/com/jme3/scene/plugins/blender/file/FileBlockHeader.java

/*
 * Copyright (c) 2009-2010 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 */
package com.jme3.scene.plugins.blender.file;

import com.jme3.scene.plugins.blender.BlenderContext;
import com.jme3.scene.plugins.blender.exceptions.BlenderFileException;

/**
 * A class that holds the header data of a file block. The file block itself is not implemented. This class holds its
 * start position in the stream and using this the structure can fill itself with the proper data.
 * @author Marcin Roguski
 */
public class FileBlockHeader {

    public static final int BLOCK_TE00 = 'T' << 24 | 'E' << 16;					//TE00
    public static final int BLOCK_ME00 = 'M' << 24 | 'E' << 16;					//ME00
    public static final int BLOCK_SR00 = 'S' << 24 | 'R' << 16;					//SR00
    public static final int BLOCK_CA00 = 'C' << 24 | 'A' << 16;					//CA00
    public static final int BLOCK_LA00 = 'L' << 24 | 'A' << 16;					//LA00
    public static final int BLOCK_OB00 = 'O' << 24 | 'B' << 16;					//OB00
    public static final int BLOCK_MA00 = 'M' << 24 | 'A' << 16;					//MA00
    public static final int BLOCK_SC00 = 'S' << 24 | 'C' << 16;					//SC00
    public static final int BLOCK_WO00 = 'W' << 24 | 'O' << 16;					//WO00
    public static final int BLOCK_TX00 = 'T' << 24 | 'X' << 16;					//TX00
    public static final int BLOCK_IP00 = 'I' << 24 | 'P' << 16;					//IP00
    public static final int BLOCK_AC00 = 'A' << 24 | 'C' << 16;					//AC00
    public static final int BLOCK_GLOB = 'G' << 24 | 'L' << 16 | 'O' << 8 | 'B';	//GLOB
    public static final int BLOCK_REND = 'R' << 24 | 'E' << 16 | 'N' << 8 | 'D';	//REND
    public static final int BLOCK_DATA = 'D' << 24 | 'A' << 16 | 'T' << 8 | 'A';	//DATA
    public static final int BLOCK_DNA1 = 'D' << 24 | 'N' << 16 | 'A' << 8 | '1';	//DNA1
    public static final int BLOCK_ENDB = 'E' << 24 | 'N' << 16 | 'D' << 8 | 'B';	//ENDB
    /** Identifier of the file-block [4 bytes]. */
    private int code;
    /** Total length of the data after the file-block-header [4 bytes]. */
    private int size;
    /**
     * Memory address the structure was located when written to disk [4 or 8 bytes (defined in file header as a pointer
     * size)].
     */
    private long oldMemoryAddress;
    /** Index of the SDNA structure [4 bytes]. */
    private int sdnaIndex;
    /** Number of structure located in this file-block [4 bytes]. */
    private int count;
    /** Start position of the block's data in the stream. */
    private int blockPosition;

    /**
     * Constructor. Loads the block header from the given stream during instance creation.
     * @param inputStream
     *        the stream we read the block header from
     * @param blenderContext
     *        the blender context
     * @throws BlenderFileException
     *         this exception is thrown when the pointer size is neither 4 nor 8
     */
    public FileBlockHeader(BlenderInputStream inputStream, BlenderContext blenderContext) throws BlenderFileException {
        inputStream.alignPosition(4);
        code = inputStream.readByte() << 24 | inputStream.readByte() << 16
                | inputStream.readByte() << 8 | inputStream.readByte();
        size = inputStream.readInt();
        oldMemoryAddress = inputStream.readPointer();
        sdnaIndex = inputStream.readInt();
        count = inputStream.readInt();
        blockPosition = inputStream.getPosition();
        if (FileBlockHeader.BLOCK_DNA1 == code) {
            blenderContext.setBlockData(new DnaBlockData(inputStream, blenderContext));
        } else {
            inputStream.setPosition(blockPosition + size);
            blenderContext.addFileBlockHeader(Long.valueOf(oldMemoryAddress), this);
        }
    }

    /**
     * This method returns the structure described by the header filled with appropriate data.
     * @param blenderContext
     *        the blender context
     * @return structure filled with data
     * @throws BlenderFileException
     */
    public Structure getStructure(BlenderContext blenderContext) throws BlenderFileException {
        blenderContext.getInputStream().setPosition(blockPosition);
        Structure structure = blenderContext.getDnaBlockData().getStructure(sdnaIndex);
        structure.fill(blenderContext.getInputStream());
        return structure;
    }

    /**
     * This method returns the code of this data block.
     * @return the code of this data block
     */
    public int getCode() {
        return code;
    }

    /**
     * This method returns the size of the data stored in this block.
     * @return the size of the data stored in this block
     */
    public int getSize() {
        return size;
    }

    /**
     * This method returns the memory address.
     * @return the memory address
     */
    public long getOldMemoryAddress() {
        return oldMemoryAddress;
    }

    /**
     * This method returns the sdna index.
     * @return the sdna index
     */
    public int getSdnaIndex() {
        return sdnaIndex;
    }

    /**
     * This data returns the number of structure stored in the data block after this header.
     * @return the number of structure stored in the data block after this header
     */
    public int getCount() {
        return count;
    }

    /**
     * This method returns the start position of the data block in the blend file stream.
     * @return the start position of the data block
     */
    public int getBlockPosition() {
        return blockPosition;
    }

    /**
     * This method indicates if the block is the last block in the file.
     * @return true if this block is the last one in the file nad false otherwise
     */
    public boolean isLastBlock() {
        return FileBlockHeader.BLOCK_ENDB == code;
    }

    /**
     * This method indicates if the block is the SDNA block.
     * @return true if this block is the SDNA block and false otherwise
     */
    public boolean isDnaBlock() {
        return FileBlockHeader.BLOCK_DNA1 == code;
    }

    @Override
    public String toString() {
        return "FILE BLOCK HEADER [" + this.codeToString(code) + " : " + size + " : " + oldMemoryAddress + " : " + sdnaIndex + " : " + count + "]";
    }

    /**
     * This method transforms the coded bloch id into a string value.
     * @param code
     *        the id of the block
     * @return the string value of the block id
     */
    protected String codeToString(int code) {
        char c1 = (char) ((code & 0xFF000000) >> 24);
        char c2 = (char) ((code & 0xFF0000) >> 16);
        char c3 = (char) ((code & 0xFF00) >> 8);
        char c4 = (char) (code & 0xFF);
        return String.valueOf(c1) + c2 + c3 + c4;
    }
}