| /******************************************************************************* |
| * 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; |
| |
| |
| /** |
| * <code>Transfer</code> provides a mechanism for converting between a java |
| * representation of data and a platform specific representation of data and |
| * vice versa. It is used in data transfer operations such as drag and drop and |
| * clipboard copy/paste. |
| * |
| * <p>You should only need to become familiar with this class if you are |
| * implementing a Transfer subclass and you are unable to subclass the |
| * ByteArrayTransfer class.</p> |
| * |
| * @see ByteArrayTransfer |
| * @see <a href="http://www.eclipse.org/swt/snippets/#dnd">Drag and Drop snippets</a> |
| * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: DNDExample</a> |
| * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> |
| */ |
| public abstract class Transfer { |
| |
| /** |
| * Returns a list of the platform specific data types that can be converted using |
| * this transfer agent. |
| * |
| * <p>Only the data type fields of the <code>TransferData</code> objects are filled |
| * in.</p> |
| * |
| * @return a list of the data types that can be converted using this transfer agent |
| */ |
| abstract public TransferData[] getSupportedTypes(); |
| |
| /** |
| * Returns true if the <code>TransferData</code> data type can be converted |
| * using this transfer agent, or false otherwise (including if transferData is |
| * <code>null</code>). |
| * |
| * @param transferData a platform specific description of a data type; only the data |
| * type fields of the <code>TransferData</code> object need to be filled in |
| * |
| * @return true if the transferData data type can be converted using this transfer |
| * agent |
| */ |
| abstract public boolean isSupportedType(TransferData transferData); |
| |
| /** |
| * Returns the platform specific ids of the data types that can be converted using |
| * this transfer agent. |
| * |
| * @return the platform specific ids of the data types that can be converted using |
| * this transfer agent |
| */ |
| abstract protected int[] getTypeIds(); |
| |
| /** |
| * Returns the platform specific names of the data types that can be converted |
| * using this transfer agent. |
| * |
| * @return the platform specific names of the data types that can be converted |
| * using this transfer agent. |
| */ |
| abstract protected String[] getTypeNames(); |
| |
| /** |
| * Converts a java representation of data to a platform specific representation of |
| * the data. |
| * |
| * <p>On a successful conversion, the transferData.result field will be set as follows: |
| * <ul> |
| * <li>Windows: COM.S_OK |
| * <li>Motif: 1 |
| * <li>GTK: 1 |
| * <li>Photon: 1 |
| * </ul></p> |
| * |
| * <p>If this transfer agent is unable to perform the conversion, the transferData.result |
| * field will be set to a failure value as follows: |
| * <ul> |
| * <li>Windows: COM.DV_E_TYMED or COM.E_FAIL |
| * <li>Motif: 0 |
| * <li>GTK: 0 |
| * <li>Photon: 0 |
| * </ul></p> |
| * |
| * @param object a java representation of the data to be converted; the type of |
| * Object that is passed in is dependent on the <code>Transfer</code> subclass. |
| * |
| * @param transferData an empty TransferData object; this object will be |
| * filled in on return with the platform specific representation of the data |
| * |
| * @exception org.eclipse.swt.SWTException <ul> |
| * <li>ERROR_INVALID_DATA - if object does not contain data in a valid format or is <code>null</code></li> |
| * </ul> |
| */ |
| abstract protected void javaToNative (Object object, TransferData transferData); |
| |
| /** |
| * Converts a platform specific representation of data to a java representation. |
| * |
| * @param transferData the platform specific representation of the data to be |
| * converted |
| * |
| * @return a java representation of the converted data if the conversion was |
| * successful; otherwise null. If transferData is <code>null</code> then |
| * <code>null</code> is returned. The type of Object that is returned is |
| * dependent on the <code>Transfer</code> subclass. |
| */ |
| abstract protected Object nativeToJava(TransferData transferData); |
| |
| /** |
| * Registers a name for a data type and returns the associated unique identifier. |
| * |
| * <p>You may register the same type more than once, the same unique identifier |
| * will be returned if the type has been previously registered.</p> |
| * |
| * <p>Note: On windows, do <b>not</b> call this method with pre-defined |
| * Clipboard Format types such as CF_TEXT or CF_BITMAP because the |
| * pre-defined identifier will not be returned</p> |
| * |
| * @param formatName the name of a data type |
| * |
| * @return the unique identifier associated with this data type |
| */ |
| public static int registerType(String formatName) { |
| int length = formatName.length(); |
| // TODO - hashcode may not be unique - need another way |
| if (length > 4) return formatName.hashCode(); |
| int type = 0; |
| if (length > 0) type |= (formatName.charAt(0) & 0xff) << 24; |
| if (length > 1) type |= (formatName.charAt(1) & 0xff) << 16; |
| if (length > 2) type |= (formatName.charAt(2) & 0xff) << 8; |
| if (length > 3) type |= formatName.charAt(3) & 0xff; |
| return type; |
| } |
| |
| /** |
| * Test that the object is of the correct format for this Transfer class. |
| * |
| * @param object a java representation of the data to be converted |
| * |
| * @return true if object is of the correct form for this transfer type |
| * |
| * @since 3.1 |
| */ |
| protected boolean validate(Object object) { |
| return true; |
| } |
| } |