/*******************************************************************************
 * Copyright (c) 2000, 2011 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;

 
import org.eclipse.swt.internal.Converter;
import org.eclipse.swt.internal.photon.OS;

/**
 * The class <code>TextTransfer</code> provides a platform specific mechanism 
 * for converting plain text represented as a java <code>String</code> 
 * to a platform specific representation of the data and vice versa.
 * 
 * <p>An example of a java <code>String</code> containing plain text is shown 
 * below:</p>
 * 
 * <code><pre>
 *     String textData = "Hello World";
 * </code></pre>
 * 
 * <p>Note the <code>TextTransfer</code> does not change the content of the text
 * data. For a better integration with the platform, the application should convert
 * the line delimiters used in the text data to the standard line delimiter used by the
 * platform.
 * </p>
 * 
 * @see Transfer
 */
public class TextTransfer extends ByteArrayTransfer {

	private static TextTransfer _instance = new TextTransfer();
	private static final String TYPENAME = "TEXT";
	private static final int TYPEID = registerType(TYPENAME);

private TextTransfer() {
}
/**
 * Returns the singleton instance of the TextTransfer class.
 *
 * @return the singleton instance of the TextTransfer class
 */
public static TextTransfer getInstance () {
	return _instance;
}
/**
 * This implementation of <code>javaToNative</code> converts plain text
 * represented by a java <code>String</code> to a platform specific representation.
 * 
 * @param object a java <code>String</code> containing text
 * @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 (!checkText(object) || !isSupportedType(transferData)) {
		DND.error(DND.ERROR_INVALID_DATA);
	}
	String string = (String)object;
	byte [] buffer = Converter.wcsToMbcs (null, string, true);
	super.javaToNative(buffer, transferData);
}
/**
 * This implementation of <code>nativeToJava</code> converts a platform specific 
 * representation of plain text to a java <code>String</code>.
 * 
 * @param transferData the platform specific representation of the data to be converted
 * @return a java <code>String</code> containing text if the conversion was successful; otherwise null
 * 
 * @see Transfer#javaToNative
 */
public Object nativeToJava(TransferData transferData){

	if (transferData.pData == 0 || !(isSupportedType(transferData))) return null;
	
	int size = transferData.length;
	if (size == 0) return null;
	byte[] buffer = new byte[OS.strlen(transferData.pData)];
	OS.memmove(buffer, transferData.pData, buffer.length);

	// convert byte array to a string
	char [] unicode = Converter.mbcsToWcs (null, buffer);
	return new String (unicode);
}
protected String[] getTypeNames(){
	return new String[]{TYPENAME};
}
protected int[] getTypeIds(){
	return new int[]{TYPEID};
}
boolean checkText(Object object) {
	return (object != null  && object instanceof String && ((String)object).length() > 0);
}
protected boolean validate(Object object) {
	return checkText(object);
}
}