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/*
* Copyright 2000-2022 Vaadin Ltd.
*
* 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.vaadin.event.dd.acceptcriteria;
import com.vaadin.event.Transferable;
import com.vaadin.server.PaintException;
import com.vaadin.server.PaintTarget;
/**
* Parent class for criteria which are verified on the server side during a drag
* operation to accept/discard dragged content (presented by
* {@link Transferable}).
* <p>
* Subclasses should implement the
* {@link AcceptCriterion#accept(com.vaadin.event.dd.DragAndDropEvent)} method.
* <p>
* As all server side state can be used to make a decision, this is more
* flexible than {@link ClientSideCriterion}. However, this does require
* additional requests from the browser to the server during a drag operation.
*
* @see AcceptCriterion
* @see ClientSideCriterion
*
* @since 6.3
*/
public abstract class ServerSideCriterion implements AcceptCriterion {
private static final long serialVersionUID = 2128510128911628902L;
@Override
public final boolean isClientSideVerifiable() {
return false;
}
@Override
public void paint(PaintTarget target) throws PaintException {
target.startTag("-ac");
target.addAttribute("name", getIdentifier());
paintContent(target);
target.endTag("-ac");
}
public void paintContent(PaintTarget target) {
}
@Override
public void paintResponse(PaintTarget target) throws PaintException {
}
protected String getIdentifier() {
return ServerSideCriterion.class.getCanonicalName();
}
}
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