/*
* Copyright 2007 Fred Sauer
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.allen_sauer.gwt.dnd.client.drop;
import com.google.gwt.user.client.ui.IndexedPanel;
import com.google.gwt.user.client.ui.Panel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.Widget;
import com.allen_sauer.gwt.dnd.client.DragContext;
import com.allen_sauer.gwt.dnd.client.VetoDragException;
import com.allen_sauer.gwt.dnd.client.util.CoordinateLocation;
import com.allen_sauer.gwt.dnd.client.util.DOMUtil;
import com.allen_sauer.gwt.dnd.client.util.LocationWidgetComparator;
import java.util.Iterator;
/**
* A {@link DropController} for {@link IndexedPanel} drop targets.
*/
public abstract class AbstractIndexedDropController extends AbstractPositioningDropController {
private int dropIndex;
private IndexedPanel dropTarget;
private Widget positioner = null;
/**
* @see FlowPanelDropController#FlowPanelDropController(com.google.gwt.user.client.ui.FlowPanel)
*
* @param dropTarget
*/
public AbstractIndexedDropController(IndexedPanel dropTarget) {
super((Panel) dropTarget);
this.dropTarget = dropTarget;
}
public void onDrop(DragContext context) {
assert dropIndex != -1 : "Should not happen after onPreviewDrop did not veto";
for (Iterator iterator = context.selectedWidgets.iterator(); iterator.hasNext();) {
Widget widget = (Widget) iterator.next();
insert(widget, dropIndex++);
}
super.onDrop(context);
}
public void onEnter(DragContext context) {
super.onEnter(context);
positioner = newPositioner(context);
}
public void onLeave(DragContext context) {
positioner.removeFromParent();
positioner = null;
super.onLeave(context);
}
public void onMove(DragContext context) {
super.onMove(context);
int targetIndex = DOMUtil.findIntersect(dropTarget, new CoordinateLocation(context.mouseX,
context.mouseY), getLocationWidgetComparator());
// check that positioner not already in the correct location
int positionerIndex = dropTarget.getWidgetIndex(positioner);
if (positionerIndex != targetIndex && (positionerIndex != targetIndex - 1 || targetIndex == 0)) {
if (positionerIndex == 0 && dropTarget.getWidgetCount() == 1) {
// do nothing, the positioner is the only widget
} else if (targetIndex == -1) {
// outside drop target, so remove positioner to indicate a drop will not happen
positioner.removeFromParent();
} else {
insert(positioner, targetIndex);
}
}
}
public void onPreviewDrop(DragContext context) throws VetoDragException {
dropIndex = dropTarget.getWidgetIndex(positioner);
if (dropIndex == -1) {
throw new VetoDragException();
}
super.onPreviewDrop(context);
}
protected abstract LocationWidgetComparator getLocationWidgetComparator();
/**
* Insert the provided widget using an appropriate drop target specific method.
*
* TODO remove after enhancement for issue 1112 provides InsertPanel interface
*
* @param widget the widget to be inserted
* @param beforeIndex the widget index before which <code>widget</code> should be inserted
*/
protected abstract void insert(Widget widget, int beforeIndex);
/**
* Called by {@link AbstractIndexedDropController#onEnter(DragContext)} to create a new
* positioner widget for this indexed drop target. Override this method to customize
* the look and feel of your positioner. The positioner widget may not have any CSS
* borders or margins, although there are no such restrictions on the children of the
* positioner widget. If borders and/or margins are desired, wrap that widget in a
* {@link SimplePanel} with a <code>0px</code> border and margin.
*
* @param context The current drag context.
* @return a new positioner widget
*/
protected abstract Widget newPositioner(DragContext context);
}