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/*
 * @(#) $Id: XMADropTargetAdapter.java 2605 2008-06-20 13:21:29Z gub $
 *
 * Copyright 2004/2005 by SPARDAT Sparkassen-Datendienst Ges.m.b.H.,
 * A-1110 Wien, Geiselbergstr.21-25.
 * All rights reserved.
 *
 */
package at.spardat.xma.event.swt;

import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.DropTargetListener;

import at.spardat.xma.page.IDialogPage;
import at.spardat.xma.page.PageClient;

/**
 * DropTargetAdapter for DropTargetListener.
 * It wraps event-disabling code of XMA around your event handling code.
 * (see package description)
 *
 * The javadoc comments of the impl methods are copied from org.eclipse.swt.dnd.DropTargetListener
 */
public class XMADropTargetAdapter implements DropTargetListener {

    PageClient page;

    /**
    *
    * @param page The page containing the widget on which you want to listen for events.
    */
    public XMADropTargetAdapter(PageClient page) {
        this.page=page;
    }

    /**
     * Returns the page passed to the contructor
     */
    public PageClient getPage() {
        return page;
    }

    /**
     * The cursor has entered the drop target boundaries.
     *
     * The following fields in the DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in)dataTypes
     * 
(in,out)currentDataType
     * 
(in)operations
     * 
(in,out)detail
     * 
(in,out)feedback
     * 

     *
     * The operation value is determined by the modifier keys pressed by the user.
     * If no keys are pressed the event.detail field is set to DND.DROP_DEFAULT.
     * If the application does not set the event.detail to something other
     * than DND.DROP_DEFAULT the operation will be set to the platform defined standard
     * default.
     *
     * The currentDataType is determined by the first transfer agent specified in
     * setTransfer() that matches a data type provided by the drag source.
     *
     * It is possible to get a DragEnter event when the drag source does not provide any matching data.
     * In this case, the default operation is DND.DROP_NONE and the currentDataType is null.
     *
     * The application can change the operation that will be performed by modifying the
     * detail field but the choice must be one of the values in the operations
     * field or DND.DROP_NONE.
     *
     * The application can also change the type of data being requested by
     * modifying the currentDataTypes field  but the value must be one of the values
     * in the dataTypes list.
     *
     * @param event  the information associated with the drag enter event
     *
     * @see DropTargetEvent
     */
    public void dragEnterImpl(DropTargetEvent event) {
    }

    /**
     * The method called by SWT whenever the corresponding event happends.
     * To not overload this method, overload {@link #dragEnterImpl(DropTargetEvent)}
     * instead.
     * @param event The event send by SWT.
     */
    final public void dragEnter(DropTargetEvent event) {
        if(!page.isEventsEnabled()) return;
        IDialogPage dialog = page.getDialogPage();
        try {
            dialog.setEventsEnabled(false);
            dragEnterImpl(event);
        } catch (Exception exc) {
            page.showException(exc);
        } finally {
            dialog.setEventsEnabled(true);
        }
    }

    /**
     * The cursor has left the drop target boundaries OR the drop has been cancelled OR the data
     * is about to be dropped.
     *
     * The following fields in the DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in)dataTypes
     * 
(in)currentDataType
     * 
(in)operations
     * 
(in)detail
     * 

     *
     * @param event  the information associated with the drag leave event
     *
     * @see DropTargetEvent
     */
    public void dragLeaveImpl(DropTargetEvent event) {
    }

    /**
     * The method called by SWT whenever the corresponding event happends.
     * To not overload this method, overload {@link #dragLeaveImpl(DropTargetEvent)}
     * instead.
     * @param event The event send by SWT.
     */
    final public void dragLeave(DropTargetEvent event) {
        if(!page.isEventsEnabled()) return;
        IDialogPage dialog = page.getDialogPage();
        try {
            dialog.setEventsEnabled(false);
            dragLeaveImpl(event);
        } catch (Exception exc) {
            page.showException(exc);
        } finally {
            dialog.setEventsEnabled(true);
        }
    }

    /**
     * The operation being performed has changed (usually due to the user changing the selected modifier key(s)
     * while dragging).
     *
     * The following fields in the DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in)dataTypes
     * 
(in,out)currentDataType
     * 
(in)operations
     * 
(in,out)detail
     * 
(in,out)feedback
     * 

     *
     * The operation value is determined by the modifier keys pressed by the user.
     * If no keys are pressed the event.detail field is set to DND.DROP_DEFAULT.
     * If the application does not set the event.detail to something other than
     * DND.DROP_DEFAULT the operation will be set to the platform defined standard default.
     *
     * The currentDataType value is determined by the value assigned to
     * currentDataType in previous dragEnter and dragOver calls.
     *
     * The application can change the operation that will be performed by modifying the
     * detail field but the choice must be one of the values in the operations
     * field.
     *
     * The application can also change the type of data being requested by modifying
     * the currentDataTypes field  but the value must be one of the values in the
     * dataTypes list.
     *
     * @param event  the information associated with the drag operation changed event
     *
     * @see DropTargetEvent
     */
    public void dragOperationChangedImpl(DropTargetEvent event) {
    }

    /**
     * The method called by SWT whenever the corresponding event happends.
     * To not overload this method, overload {@link #dragOperationChangedImpl(DropTargetEvent)}
     * instead.
     * @param event The event send by SWT.
     */
    final public void dragOperationChanged(DropTargetEvent event) {
        if(!page.isEventsEnabled()) return;
        IDialogPage dialog = page.getDialogPage();
        try {
            dialog.setEventsEnabled(false);
            dragOperationChangedImpl(event);
        } catch (Exception exc) {
            page.showException(exc);
        } finally {
            dialog.setEventsEnabled(true);
        }
    }

    /**
     * The data is being dropped.  The data field contains java format of the data being dropped.
     * To determine the type of the data object, refer to the documentation for the Transfer subclass
     * specified in event.currentDataType.
     *
     * The following fields in DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in,out)detail
     * 
(in)currentDataType
     * 
(in)data
     * 

     *
     * The application can refuse to perform the drop operation by setting the detail
     * field to DND.DROP_NONE.
     *
     * @param event the information associated with the drop event
     *
     * @see DropTargetEvent
     */
    public void dropImpl(DropTargetEvent event) {
    }

    /**
     * The method called by SWT whenever the corresponding event happends.
     * To not overload this method, overload {@link #dropImpl(DropTargetEvent)}
     * instead.
     * @param event The event send by SWT.
     */
    final public void drop(DropTargetEvent event) {
        if(!page.isEventsEnabled()) return;
        IDialogPage dialog = page.getDialogPage();
        try {
            dialog.setEventsEnabled(false);
            dropImpl(event);
        } catch (Exception exc) {
            page.showException(exc);
        } finally {
            dialog.setEventsEnabled(true);
        }
    }

    /**
     * The drop is about to be performed.
     * The drop target is given a last chance to change the nature of the drop.
     *
     * The following fields in the DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in)dataTypes
     * 
(in,out)currentDataType
     * 
(in)operations
     * 
(in,out)detail
     * 

     *
     * The application can veto the drop by setting the event.detail field to
     * DND.DROP_NONE.
     *
     * The application can change the operation that will be performed by modifying the
     * detail field but the choice must be one of the values in the
     * operations field.
     *
     * The application can also change the type of data being requested by modifying the
     * currentDataTypes field  but the value must be one of the values in the <
     * code>dataTypes list.
     *
     * @param event  the information associated with the drop accept event
     *
     * @see DropTargetEvent
     */
    public void dropAcceptImpl(DropTargetEvent event) {
    }

    /**
     * The method called by SWT whenever the corresponding event happends.
     * To not overload this method, overload {@link #dropAcceptImpl(DropTargetEvent)}
     * instead.
     * @param event The event send by SWT.
     */
    final public void dropAccept(DropTargetEvent event) {
        if(!page.isEventsEnabled()) return;
        IDialogPage dialog = page.getDialogPage();
        try {
            dialog.setEventsEnabled(false);
            dropAcceptImpl(event);
        } catch (Exception exc) {
            page.showException(exc);
        } finally {
            dialog.setEventsEnabled(true);
        }
    }

    /**
     * The cursor is moving over the drop target.
     * This method is not overwritten by the XMADropTargetAdapter as it is called so often.
     *
     * The following fields in the DropTargetEvent apply:
     * 

     * (in)widget
     * 
(in)time
     * 
(in)x
     * 
(in)y
     * 
(in)dataTypes
     * 
(in,out)currentDataType
     * 
(in)operations
     * 
(in,out)detail
     * 
(in,out)feedback
     * 

     *
     * The operation value is determined by the value assigned to
     * currentDataType in previous dragEnter and dragOver calls.
     *
     * The currentDataType value is determined by the value assigned to
     * currentDataType in previous dragEnter and dragOver calls.
     *
     * The application can change the operation that will be performed by modifying the
     * detail field but the choice must be one of the values in the operations
     * field.
     *
     * The application can also change the type of data being requested by modifying the
     * currentDataTypes field  but the value must be one of the values in the
     * dataTypes list.
     *
     * NOTE: At this point the data field is null.  On some platforms, it is possible
     * to obtain the data being transferred before the transfer occurs but in most platforms this is
     * not possible.  On those platforms where the data is available, the application can access the
     * data as follows:
     *
     * 
     * public void dragOver(DropTargetEvent event) {
     *       TextTransfer textTransfer = TextTransfer.getInstance();
     *       String data = (String)textTransfer.nativeToJava(event.currentDataType);
     *       if (data != null) {
     *           System.out.println("Data to be dropped is (Text)"+data);
     *       }
     * };
     * 
     *
     * @param event  the information associated with the drag over event
     *
     * @see DropTargetEvent
     */
    public void dragOver(DropTargetEvent event) {
    }
}
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