/*******************************************************************************
* Copyright (c) 2000, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.dnd;
/**
* The class <code>ByteArrayTransfer</code> provides a platform specific
* mechanism for converting a java <code>byte[]</code> to a platform
* specific representation of the byte array and vice versa.
*
* <p><code>ByteArrayTransfer</code> is never used directly but is sub-classed
* by transfer agents that convert between data in a java format such as a
* <code>String</code> and a platform specific byte array.
*
* <p>If the data you are converting <b>does not</b> map to a
* <code>byte[]</code>, you should sub-class <code>Transfer</code> directly
* and do your own mapping to a platform data type.</p>
*
* <p>The following snippet shows a subclass of ByteArrayTransfer that transfers
* data defined by the class <code>MyType</code>.</p>
*
* <pre><code>
* public class MyType {
* public String fileName;
* public long fileLength;
* public long lastModified;
* }
* </code></pre>
*
* <pre><code>
* public class MyTypeTransfer extends ByteArrayTransfer {
*
* private static final String MYTYPENAME = "my_type_name";
* private static final int MYTYPEID = registerType(MYTYPENAME);
* private static MyTypeTransfer _instance = new MyTypeTransfer();
*
* private MyTypeTransfer() {}
*
* public static MyTypeTransfer getInstance () {
* return _instance;
* }
* public void javaToNative (Object object, TransferData transferData) {
* if (object == null || !(object instanceof MyType[])) return;
*
* if (isSupportedType(transferData)) {
* MyType[] myTypes = (MyType[]) object;
* try {
* // write data to a byte array and then ask super to convert to pMedium
* ByteArrayOutputStream out = new ByteArrayOutputStream();
* DataOutputStream writeOut = new DataOutputStream(out);
* for (int i = 0, length = myTypes.length; i < length; i++){
* byte[] buffer = myTypes[i].fileName.getBytes();
* writeOut.writeInt(buffer.length);
* writeOut.write(buffer);
* writeOut.writeLong(myTypes[i].fileLength);
* writeOut.writeLong(myTypes[i].lastModified);
* }
* byte[] buffer = out.toByteArray();
* writeOut.close();
*
* super.javaToNative(buffer, transferData);
*
* } catch (IOException e) {
* }
* }
* }
* public Object nativeToJava(TransferData transferData){
*
* if (isSupportedType(transferData)) {
*
* byte[] buffer = (byte[])super.nativeToJava(transferData);
* if (buffer == null) return null;
*
* MyType[] myData = new MyType[0];
* try {
* ByteArrayInputStream in = new ByteArrayInputStream(buffer);
* DataInputStream readIn = new DataInputStream(in);
* while(readIn.available() > 20) {
* MyType datum = new MyType();
* int size = readIn.readInt();
* byte[] name = new byte[size];
* readIn.read(name);
* datum.fileName = new String(name);
* datum.fileLength = readIn.readLong();
* datum.lastModified = readIn.readLong();
* MyType[] newMyData = new MyType[myData.length + 1];
* System.arraycopy(myData, 0, newMyData, 0, myData.length);
* newMyData[myData.length] = datum;
* myData = newMyData;
* }
* readIn.close();
* } catch (IOException ex) {
* return null;
* }
* return myData;
* }
*
* return null;
* }
* protected String[] getTypeNames(){
* return new String[]{MYTYPENAME};
* }
* protected int[] getTypeIds(){
* return new int[] {MYTYPEID};
* }
* }
* </code></pre>
*
* @see Transfer
* @since 1.3
*/
public abstract class ByteArrayTransfer extends Transfer {
public TransferData[] getSupportedTypes() {
int[] types = getTypeIds();
TransferData[] data = new TransferData[ types.length ];
for( int i = 0; i < types.length; i++ ) {
data[ i ] = new TransferData();
data[ i ].type = types[ i ];
}
return data;
}
public boolean isSupportedType( TransferData transferData ) {
boolean result = false;
if( transferData != null ) {
int[] types = getTypeIds();
for( int i = 0; !result && i < types.length; i++ ) {
if( transferData.type == types[ i ] )
result = true;
}
}
return result;
}
/**
* This implementation of <code>javaToNative</code> converts a java
* <code>byte[]</code> to a platform specific representation.
*
* @param object a java <code>byte[]</code> containing the data to be
* converted
* @param transferData an empty <code>TransferData</code> object that will be
* filled in on return with the platform specific format of the data
* @see Transfer#nativeToJava
*/
public void javaToNative( Object object, TransferData transferData ) {
if( !checkByteArray( object ) || !isSupportedType( transferData ) ) {
DND.error( DND.ERROR_INVALID_DATA );
}
byte[] data = ( byte[] )object;
transferData.data = new byte[ data.length ];
System.arraycopy( data, 0, transferData.data, 0, data.length );
transferData.result = 1;
}
/**
* This implementation of <code>nativeToJava</code> converts a platform
* specific representation of a byte array to a java <code>byte[]</code>.
*
* @param transferData the platform specific representation of the data to be
* converted
* @return a java <code>byte[]</code> containing the converted data if the
* conversion was successful; otherwise null
* @see Transfer#javaToNative
*/
public Object nativeToJava( TransferData transferData ) {
byte[] result = null;
if( isSupportedType( transferData )
&& ( transferData.data instanceof byte[] ) )
{
byte[] data = ( byte[] )transferData.data;
result = new byte[ data.length ];
System.arraycopy( data, 0, result, 0, data.length );
}
return result;
}
private static boolean checkByteArray( Object object ) {
return object != null && object instanceof byte[]
&& ( ( byte[] )object ).length > 0;
}
}