ca.odell.glazedlists.swt.DefaultEventComboViewer Maven / Gradle / Ivy
/* Glazed Lists (c) 2003-2012 */
/* http://publicobject.com/glazedlists/ publicboject.com,*/
/* O'Dell Engineering Ltd.*/
package ca.odell.glazedlists.swt;
import ca.odell.glazedlists.EventList;
import ca.odell.glazedlists.event.ListEvent;
import ca.odell.glazedlists.event.ListEventListener;
import org.eclipse.swt.widgets.Combo;
/**
* A view helper that displays an {@link EventList} in a {@link Combo} component.
*
* This class is not thread safe. It must be used exclusively with the SWT
* event handler thread.
*
* @author Kevin Maltby
* @author Holger Brands
*/
public class DefaultEventComboViewer implements ListEventListener {
/** indicator to dispose source list */
private boolean disposeSource;
/** the SWT Combo component */
private Combo combo;
/** the EventList to respond to */
protected EventList source;
/** the {@link ItemFormat} to pretty print a String representation of each Object */
private ItemFormat itemFormat;
/**
* Binds the contents of a {@link Combo} component to an {@link EventList}
* source. This allows the selection choices in a {@link Combo} to change
* dynamically to reflect chances to the source {@link EventList}. The
* {@link String} values displayed in the {@link Combo} component will be
* the result of calling toString() on the Objects found in source.
*
* @param source the EventList that provides the elements
* @param combo the combo box
*/
public DefaultEventComboViewer(EventList source, Combo combo) {
this(source, combo, new DefaultItemFormat());
}
/**
* Binds the contents of a {@link Combo} component to an {@link EventList}
* source. This allows the selection choices in a {@link Combo} to change
* dynamically to reflect chances to the source {@link EventList}. The
* {@link String} values displayed in the {@link Combo} component will be
* formatted using the provided {@link ItemFormat}.
*
* @param source the EventList that provides the elements
* @param combo the combo box
* @param itemFormat an {@link ItemFormat} for formatting the displayed values
*
* @see ItemFormat
* @see GlazedListsSWT#beanItemFormat(String)
*/
public DefaultEventComboViewer(EventList source, Combo combo, ItemFormat itemFormat) {
this(source, combo, itemFormat, false);
}
/**
* Binds the contents of a {@link Combo} component to an {@link EventList}
* source. This allows the selection choices in a {@link Combo} to change
* dynamically to reflect chances to the source {@link EventList}. The
* {@link String} values displayed in the {@link Combo} component will be
* formatted using the provided {@link ItemFormat}.
*
* @param source the EventList that provides the elements
* @param combo the combo box
* @param itemFormat an optional {@link ItemFormat} for formatting the displayed values
* @param diposeSource true if the source list should be disposed when disposing
* this model, false otherwise
*
* @see ItemFormat
* @see GlazedListsSWT#beanItemFormat(String)
*/
protected DefaultEventComboViewer(EventList source, Combo combo,
ItemFormat itemFormat, boolean disposeSource) {
this.disposeSource = disposeSource;
// lock the source list for reading since we want to prevent writes
// from occurring until we fully initialize this EventComboViewer
source.getReadWriteLock().readLock().lock();
try {
this.source = source;
this.combo = combo;
this.itemFormat = itemFormat;
// set the initial data
for(int i = 0, n = source.size(); i < n; i++) {
addRow(i, source.get(i));
}
// listen for changes
this.source.addListEventListener(this);
} finally {
source.getReadWriteLock().readLock().unlock();
}
}
/**
* Gets the Combo being managed by this {@link DefaulEventComboViewer}.
*/
public Combo getCombo() {
return combo;
}
/**
* Gets the Combo's {@link ItemFormat}.
*/
public ItemFormat getItemFormat() {
return itemFormat;
}
/**
* Adds the value at the specified row.
*/
private void addRow(int row, E value) {
combo.add(itemFormat.format(value), row);
}
/**
* Updates the value at the specified row.
*/
private void updateRow(int row, E value) {
combo.setItem(row, itemFormat.format(value));
}
/**
* Removes the value at the specified row.
*/
private void deleteRow(int row) {
combo.remove(row);
}
/**
* When the source combo is changed, this forwards the change to the
* displayed combo.
*/
public void listChanged(ListEvent listChanges) {
// apply the combo changes
while (listChanges.next()) {
int changeIndex = listChanges.getIndex();
int changeType = listChanges.getType();
if (changeType == ListEvent.INSERT)
addRow(changeIndex, source.get(changeIndex));
else if (changeType == ListEvent.UPDATE)
updateRow(changeIndex, source.get(changeIndex));
else if (changeType == ListEvent.DELETE)
deleteRow(changeIndex);
}
}
/**
* Releases the resources consumed by this {@link DefaultEventComboViewer} so that it
* may eventually be garbage collected.
*
* An {@link DefaultEventComboViewer} will be garbage collected without a call to
* {@link #dispose()}, but not before its source {@link EventList} is garbage
* collected. By calling {@link #dispose()}, you allow the {@link DefaultEventComboViewer}
* to be garbage collected before its source {@link EventList}. This is
* necessary for situations where an {@link DefaultEventComboViewer} is short-lived but
* its source {@link EventList} is long-lived.
*
*
Warning: It is an error
* to call any method on a {@link DefaultEventComboViewer} after it has been disposed.
*/
public void dispose() {
source.removeListEventListener(this);
if (disposeSource) source.dispose();
}
}