org.eclipse.swt.dnd.TextTransfer.java Source code

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Here is the source code for org.eclipse.swt.dnd.TextTransfer.java

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/*******************************************************************************
 * 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;

import java.io.UnsupportedEncodingException;

import org.eclipse.rap.rwt.SingletonUtil;

/**
 * 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
 * @since 1.3
 */
public class TextTransfer extends ByteArrayTransfer {

    private static final String TYPE_NAME = "text";
    private static final int TYPE_ID = registerType(TYPE_NAME);

    private TextTransfer() {
    }

    /**
     * Returns the singleton instance of the TextTransfer class.
     * 
     * @return the singleton instance of the TextTransfer class
     */
    public static TextTransfer getInstance() {
        return SingletonUtil.getSessionInstance(TextTransfer.class);
    }

    /**
     * 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);
        }
        transferData.data = object;
        transferData.result = 1;
    }

    /**
     * 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 (!isSupportedType(transferData) || transferData.data == null) {
            return null;
        }
        if (transferData.result != 1)
            return null;
        return transferData.data;
    }

    protected int[] getTypeIds() {
        return new int[] { TYPE_ID };
    }

    protected String[] getTypeNames() {
        return new String[] { TYPE_NAME };
    }

    boolean checkText(Object object) {
        return (object != null && object instanceof String && ((String) object).length() > 0);
    }

    protected boolean validate(Object object) {
        return checkText(object);
    }

    static byte[] stringToBytes(String string) {
        byte[] bytes = null;
        try {
            bytes = string.getBytes("UTF-8");
        } catch (UnsupportedEncodingException ignore) {
        }
        return bytes;
    }
}