001// Copyright 2007, 2008, 2010, 2011 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.internal.services;
016
017import org.apache.tapestry5.Asset;
018import org.apache.tapestry5.ComponentResources;
019import org.apache.tapestry5.annotations.Path;
020import org.apache.tapestry5.ioc.ObjectLocator;
021import org.apache.tapestry5.model.MutableComponentModel;
022import org.apache.tapestry5.plastic.ComputedValue;
023import org.apache.tapestry5.plastic.InstanceContext;
024import org.apache.tapestry5.plastic.PlasticField;
025import org.apache.tapestry5.services.AssetSource;
026import org.apache.tapestry5.services.transform.InjectionProvider2;
027
028/**
029 * Performs injection of assets, based on the presence of the {@link Path} annotation. This is more
030 * useful than the
031 * general {@link AssetObjectProvider}, because relative assets are supported.
032 */
033public class AssetInjectionProvider implements InjectionProvider2
034{
035    private final AssetSource assetSource;
036
037    public AssetInjectionProvider(AssetSource assetSource)
038    {
039        this.assetSource = assetSource;
040    }
041
042    public boolean provideInjection(PlasticField field, ObjectLocator locator, MutableComponentModel componentModel)
043    {
044        Path path = field.getAnnotation(Path.class);
045
046        if (path == null)
047        {
048            return false;
049        }
050
051        final String assetPath = path.value();
052
053        ComputedValue<Asset> computedAsset = new ComputedValue<Asset>()
054        {
055            public Asset get(InstanceContext context)
056            {
057                ComponentResources resources = context.get(ComponentResources.class);
058
059                return assetSource.getComponentAsset(resources, assetPath);
060            }
061        };
062
063        field.injectComputed(computedAsset);
064
065        return true;
066    }
067
068}