/*******************************************************************************
 * 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.swt.*;
import org.eclipse.swt.widgets.*;

/**
 * The <code>Clipboard</code> provides a mechanism for transferring data from one
 * application to another or within an application.
 * 
 * <p>IMPORTANT: This class is <em>not</em> intended to be subclassed.</p>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#clipboard">Clipboard snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ClipboardExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public class Clipboard {

	private Display display;

/**
 * Constructs a new instance of this class.  Creating an instance of a Clipboard
 * may cause system resources to be allocated depending on the platform.  It is therefore
 * mandatory that the Clipboard instance be disposed when no longer required.
 *
 * @param display the display on which to allocate the clipboard
 *
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see Clipboard#dispose
 * @see Clipboard#checkSubclass
 */
public Clipboard(Display display) {	
	checkSubclass ();
	if (display == null) {
		display = Display.getCurrent();
		if (display == null) {
			display = Display.getDefault();
		}
	}
	if (display.getThread() != Thread.currentThread()) {
		DND.error(SWT.ERROR_THREAD_INVALID_ACCESS);
	}
	this.display = display;
}

/**
 * Checks that this class can be subclassed.
 * <p>
 * The SWT class library is intended to be subclassed 
 * only at specific, controlled points. This method enforces this
 * rule unless it is overridden.
 * </p><p>
 * <em>IMPORTANT:</em> By providing an implementation of this
 * method that allows a subclass of a class which does not 
 * normally allow subclassing to be created, the implementer
 * agrees to be fully responsible for the fact that any such
 * subclass will likely fail between SWT releases and will be
 * strongly platform specific. No support is provided for
 * user-written classes which are implemented in this fashion.
 * </p><p>
 * The ability to subclass outside of the allowed SWT classes
 * is intended purely to enable those not on the SWT development
 * team to implement patches in order to get around specific
 * limitations in advance of when those limitations can be
 * addressed by the team. Subclassing should not be attempted
 * without an intimate and detailed understanding of the hierarchy.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 */
protected void checkSubclass () {
	String name = getClass().getName ();
	String validName = Clipboard.class.getName();
	if (!validName.equals(name)) {
		DND.error (SWT.ERROR_INVALID_SUBCLASS);
	}
}

/**
 * Throws an <code>SWTException</code> if the receiver can not
 * be accessed by the caller. This may include both checks on
 * the state of the receiver and more generally on the entire
 * execution context. This method <em>should</em> be called by
 * widget implementors to enforce the standard SWT invariants.
 * <p>
 * Currently, it is an error to invoke any method (other than
 * <code>isDisposed()</code>) on a widget that has had its 
 * <code>dispose()</code> method called. It is also an error
 * to call widget methods from any thread that is different
 * from the thread that created the widget.
 * </p><p>
 * In future releases of SWT, there may be more or fewer error
 * checks and exceptions may be thrown for different reasons.
 * </p>
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
protected void checkWidget () {
	Display display = this.display;
	if (display == null) DND.error (SWT.ERROR_WIDGET_DISPOSED);
	if (display.getThread() != Thread.currentThread ()) DND.error (SWT.ERROR_THREAD_INVALID_ACCESS);
	if (display.isDisposed()) DND.error(SWT.ERROR_WIDGET_DISPOSED);
}

/**
 * Disposes of the operating system resources associated with the clipboard. 
 * The data will still be available on the system clipboard after the dispose 
 * method is called.  
 * 
 * <p>NOTE: On some platforms the data will not be available once the application
 * has exited or the display has been disposed.</p>
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 * </ul>
 */
public void dispose () {
	if (isDisposed()) return;
	if (display.getThread() != Thread.currentThread()) DND.error(SWT.ERROR_THREAD_INVALID_ACCESS);
	display = null;
}

/**
 * Retrieve the data of the specified type currently available on the system 
 * clipboard.  Refer to the specific subclass of <code>Transfer</code> to 
 * determine the type of object returned.
 * 
 * <p>The following snippet shows text and RTF text being retrieved from the 
 * clipboard:</p>
 * 
 *    <code><pre>
 *    Clipboard clipboard = new Clipboard(display);
 *    TextTransfer textTransfer = TextTransfer.getInstance();
 *    String textData = (String)clipboard.getContents(textTransfer);
 *    if (textData != null) System.out.println("Text is "+textData);
 *    RTFTransfer rtfTransfer = RTFTransfer.getInstance();
 *    String rtfData = (String)clipboard.getContents(rtfTransfer);
 *    if (rtfData != null) System.out.println("RTF Text is "+rtfData);
 *    clipboard.dispose();
 *    </code></pre>
 * 
 * @param transfer the transfer agent for the type of data being requested
 * @return the data obtained from the clipboard or null if no data of this type is available
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if transfer is null</li>
 * </ul>
 * 
 * @see Transfer
 */
public Object getContents(Transfer transfer) {
	return getContents(transfer, DND.CLIPBOARD);
}

/**
 * Retrieve the data of the specified type currently available on the specified 
 * clipboard.  Refer to the specific subclass of <code>Transfer</code> to 
 * determine the type of object returned.
 * 
 * <p>The following snippet shows text and RTF text being retrieved from the 
 * clipboard:</p>
 * 
 *    <code><pre>
 *    Clipboard clipboard = new Clipboard(display);
 *    TextTransfer textTransfer = TextTransfer.getInstance();
 *    String textData = (String)clipboard.getContents(textTransfer);
 *    if (textData != null) System.out.println("Text is "+textData);
 *    RTFTransfer rtfTransfer = RTFTransfer.getInstance();
 *    String rtfData = (String)clipboard.getContents(rtfTransfer, DND.CLIPBOARD);
 *    if (rtfData != null) System.out.println("RTF Text is "+rtfData);
 *    clipboard.dispose();
 *    </code></pre>
 * 
 * <p>The clipboards value is either one of the clipboard constants defined in
 * class <code>DND</code>, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>DND</code> clipboard constants.</p>
 * 
 * @param transfer the transfer agent for the type of data being requested
 * @param clipboards on which to look for data
 *  
 * @return the data obtained from the clipboard or null if no data of this type is available
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if transfer is null</li>
 * </ul>
 * 
 * @see Transfer
 * @see DND#CLIPBOARD
 * @see DND#SELECTION_CLIPBOARD
 * 
 * @since 3.1
 */
public Object getContents(Transfer transfer, int clipboards) {
	checkWidget();
	if (transfer == null) DND.error(SWT.ERROR_NULL_ARGUMENT);
	if (!(transfer instanceof TextTransfer)) return null;
	return display.getData("TextTransfer"); //$NON-NLS-1$
}

/**
 * Returns <code>true</code> if the clipboard has been disposed,
 * and <code>false</code> otherwise.
 * <p>
 * This method gets the dispose state for the clipboard.
 * When a clipboard has been disposed, it is an error to
 * invoke any other method using the clipboard.
 * </p>
 *
 * @return <code>true</code> when the widget is disposed and <code>false</code> otherwise
 * 
 * @since 3.0
 */
public boolean isDisposed () {
	return (display == null);
}

/**
 * Place data of the specified type on the system clipboard.  More than one type
 * of data can be placed on the system clipboard at the same time.  Setting the
 * data clears any previous data from the system clipboard, regardless of type.
 * 
 * <p>NOTE: On some platforms, the data is immediately copied to the system
 * clipboard but on other platforms it is provided upon request.  As a result,
 * if the application modifies the data object it has set on the clipboard, that 
 * modification may or may not be available when the data is subsequently 
 * requested.</p>
 *
 * <p>The following snippet shows text and RTF text being set on the copy/paste
 * clipboard:
 * </p>
 * 
 * <code><pre>
 * 	Clipboard clipboard = new Clipboard(display);
 *	String textData = "Hello World";
 *	String rtfData = "{\\rtf1\\b\\i Hello World}";
 *	TextTransfer textTransfer = TextTransfer.getInstance();
 *	RTFTransfer rtfTransfer = RTFTransfer.getInstance();
 *	Transfer[] transfers = new Transfer[]{textTransfer, rtfTransfer};
 *	Object[] data = new Object[]{textData, rtfData};
 *	clipboard.setContents(data, transfers);
 *	clipboard.dispose();
 * </code></pre>
 *
 * @param data the data to be set in the clipboard
 * @param dataTypes the transfer agents that will convert the data to its 
 * platform specific format; each entry in the data array must have a 
 * corresponding dataType
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if data is null or datatypes is null 
 *          or the length of data is not the same as the length of dataTypes</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *  @exception SWTError <ul>
 *    <li>ERROR_CANNOT_SET_CLIPBOARD - if the clipboard is locked or otherwise unavailable</li>
 * </ul>
 * 
 * <p>NOTE: ERROR_CANNOT_SET_CLIPBOARD should be an SWTException, since it is a
 * recoverable error, but can not be changed due to backward compatibility.</p>
 */
public void setContents(Object[] data, Transfer[] dataTypes) {
	setContents(data, dataTypes, DND.CLIPBOARD);
}

/**
 * Place data of the specified type on the specified clipboard.  More than one 
 * type of data can be placed on the specified clipboard at the same time.
 * Setting the data clears any previous data from the specified
 * clipboard, regardless of type.
 * 
 * <p>NOTE: On some platforms, the data is immediately copied to the specified
 * clipboard but on other platforms it is provided upon request.  As a result, 
 * if the application modifies the data object it has set on the clipboard, that 
 * modification may or may not be available when the data is subsequently 
 * requested.</p>
 *
 * <p>The clipboards value is either one of the clipboard constants defined in
 * class <code>DND</code>, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>DND</code> clipboard constants.</p>
 * 
 * <p>The following snippet shows text and RTF text being set on the copy/paste
 * clipboard:
 * </p>
 * 
 * <code><pre>
 * 	Clipboard clipboard = new Clipboard(display);
 *	String textData = "Hello World";
 *	String rtfData = "{\\rtf1\\b\\i Hello World}";
 *	TextTransfer textTransfer = TextTransfer.getInstance();
 *	RTFTransfer rtfTransfer = RTFTransfer.getInstance();
 *	Transfer[] transfers = new Transfer[]{textTransfer, rtfTransfer};
 *	Object[] data = new Object[]{textData, rtfData};
 *	clipboard.setContents(data, transfers, DND.CLIPBOARD);
 *	clipboard.dispose();
 * </code></pre>
 *
 * @param data the data to be set in the clipboard
 * @param dataTypes the transfer agents that will convert the data to its 
 * platform specific format; each entry in the data array must have a 
 * corresponding dataType
 * @param clipboards on which to set the data
 * 
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if data is null or datatypes is null 
 *          or the length of data is not the same as the length of dataTypes</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *  @exception SWTError <ul>
 *    <li>ERROR_CANNOT_SET_CLIPBOARD - if the clipboard is locked or otherwise unavailable</li>
 * </ul>
 * 
 * <p>NOTE: ERROR_CANNOT_SET_CLIPBOARD should be an SWTException, since it is a
 * recoverable error, but can not be changed due to backward compatibility.</p>
 * 
 * @see DND#CLIPBOARD
 * @see DND#SELECTION_CLIPBOARD
 * 
 * @since 3.1
 */
public void setContents(Object[] data, Transfer[] dataTypes, int clipboards) {
	checkWidget();
	if (data == null || dataTypes == null || data.length != dataTypes.length) {
		DND.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	
	for (int i = 0; i < dataTypes.length; i++) {
		if (dataTypes[i] instanceof TextTransfer && data[i] instanceof String){
			display.setData("TextTransfer", data[i]); //$NON-NLS-1$
			return;
		}
	}
}

/**
 * Returns an array of the data types currently available on the system 
 * clipboard. Use with Transfer.isSupportedType.
 *
 * @return array of data types currently available on the system clipboard
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see Transfer#isSupportedType
 * 
 * @since 3.0
 */
public TransferData[] getAvailableTypes() {
	checkWidget();
	return new TransferData[0];
}

/**
 * Returns a platform specific list of the data types currently available on the 
 * system clipboard.
 * 
 * <p>Note: <code>getAvailableTypeNames</code> is a utility for writing a Transfer 
 * sub-class.  It should NOT be used within an application because it provides 
 * platform specific information.</p>
 * 
 * @return a platform specific list of the data types currently available on the 
 * system clipboard
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public String[] getAvailableTypeNames() {
	checkWidget();
	return new String[0];
}
}
