    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.internal.services;
    014
    015import org.apache.tapestry5.Asset;
    016import org.apache.tapestry5.ComponentResources;
    017import org.apache.tapestry5.annotations.Path;
    018import org.apache.tapestry5.commons.ObjectLocator;
    019import org.apache.tapestry5.model.MutableComponentModel;
    020import org.apache.tapestry5.plastic.ComputedValue;
    021import org.apache.tapestry5.plastic.InstanceContext;
    022import org.apache.tapestry5.plastic.PlasticField;
    023import org.apache.tapestry5.services.AssetSource;
    024import org.apache.tapestry5.services.transform.InjectionProvider2;
    025
    026/**
    027 * Performs injection of assets, based on the presence of the {@link Path} annotation. This is more
    028 * useful than the
    029 * general {@link AssetObjectProvider}, because relative assets are supported.
    030 */
    031public class AssetInjectionProvider implements InjectionProvider2
    032{
    033    private final AssetSource assetSource;
    034
    035    public AssetInjectionProvider(AssetSource assetSource)
    036    {
    037        this.assetSource = assetSource;
    038    }
    039
    040    public boolean provideInjection(PlasticField field, ObjectLocator locator, MutableComponentModel componentModel)
    041    {
    042        Path path = field.getAnnotation(Path.class);
    043
    044        if (path == null)
    045        {
    046            return false;
    047        }
    048
    049        final String assetPath = path.value();
    050        final String libraryName = componentModel.getLibraryName();
    051
    052        ComputedValue<Asset> computedAsset = new ComputedValue<Asset>()
    053        {
    054            public Asset get(InstanceContext context)
    055            {
    056                ComponentResources resources = context.get(ComponentResources.class);
    057
    058                // Note how this works: the resources represents the actual instantiated class, and the libraryName
    059                // comes from the componentModel, potentially, the componentModel of a base class (which may have
    060                // a different library name than the subclass).
    061                return assetSource.getComponentAsset(resources, assetPath, libraryName);
    062            }
    063        };
    064
    065        field.injectComputed(computedAsset);
    066
    067        return true;
    068    }
    069
    070}