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

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Here is the source code for org.eclipse.swt.dnd.HTMLTransfer.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 org.eclipse.rap.rwt.SingletonUtil;

/**
 * The class <code>HTMLTransfer</code> provides a platform specific mechanism
 * for converting text in HTML format 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 HTML text is shown below:
 * </p>
 * <code><pre>
 *     String htmlData = "<p>This is a paragraph of text.</p>";
 * </code></pre>
 * 
 * @see Transfer
 */
public class HTMLTransfer extends ByteArrayTransfer {

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

    private HTMLTransfer() {
    }

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

    /**
     * This implementation of <code>javaToNative</code> converts HTML-formatted
     * text represented by a java <code>String</code> to a platform specific
     * representation.
     * 
     * @param object a java <code>String</code> containing HTML 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 (!checkHTML(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 HTML 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 HTML 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 checkHTML(Object object) {
        return (object != null && object instanceof String && ((String) object).length() > 0);
    }

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