001// Copyright 2008, 2009 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.corelib.base;
016
017import org.apache.tapestry5.BindingConstants;
018import org.apache.tapestry5.Link;
019import org.apache.tapestry5.MarkupConstants;
020import org.apache.tapestry5.MarkupWriter;
021import org.apache.tapestry5.annotations.Environmental;
022import org.apache.tapestry5.annotations.Parameter;
023import org.apache.tapestry5.ioc.annotations.Inject;
024import org.apache.tapestry5.services.ClientBehaviorSupport;
025import org.apache.tapestry5.services.Request;
026
027/**
028 * Base class for link-generating components that are based on a component event request. Such events have an event
029 * context and may also update a {@link org.apache.tapestry5.corelib.components.Zone}.
030 */
031public abstract class AbstractComponentEventLink extends AbstractLink
032{
033    /**
034     * The context for the link (optional parameter). This list of values will be converted into strings and included in
035     * the URI. The strings will be coerced back to whatever their values are and made available to event handler
036     * methods.
037     */
038    @Parameter
039    private Object[] context;
040
041    /**
042     * Binding the zone parameter turns the link into a an Ajax control that causes the related zone to be updated.
043     */
044    @Parameter(defaultPrefix = BindingConstants.LITERAL)
045    private String zone;
046
047    @Environmental
048    private ClientBehaviorSupport clientBehaviorSupport;
049
050    @Inject
051    private Request request;
052
053    void beginRender(MarkupWriter writer)
054    {
055        if (isDisabled()) return;
056
057        Link link = createLink(context);
058
059        writeLink(writer, link);
060
061        if (zone != null)
062        {
063            if (!request.isXHR())
064                writer.getElement().forceAttributes(MarkupConstants.ONCLICK, MarkupConstants.WAIT_FOR_PAGE);
065
066            clientBehaviorSupport.linkZone(getClientId(), zone, link);
067        }
068    }
069
070    /**
071     * Invoked to create the Link that will become the href attribute of the output.
072     *
073     * @param eventContext the context as an object array, possibly null
074     */
075    protected abstract Link createLink(Object[] eventContext);
076
077    void afterRender(MarkupWriter writer)
078    {
079        if (isDisabled()) return;
080
081        writer.end(); // <a>
082    }
083}