/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.wicket.markup.html.image;
import java.lang.reflect.Method;
import org.apache.wicket.Component;
import org.apache.wicket.IResourceListener;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.markup.html.WebComponent;
import org.apache.wicket.markup.html.image.resource.LocalizedImageResource;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.request.resource.IResource;
import org.apache.wicket.request.resource.ResourceReference;
/**
* An Image component displays a localizable image resource.
* <p>
* For details of how Images load, generate and manage images, see {@link LocalizedImageResource}.
*
* @see NonCachingImage
*
* @author Jonathan Locke
*
*/
public class Image extends WebComponent implements IResourceListener
{
private static final long serialVersionUID = 1L;
/** The image resource this image component references */
private final LocalizedImageResource localizedImageResource = new LocalizedImageResource(this);
/**
* This constructor can be used if you override {@link #getImageResourceReference()} or
* {@link #getImageResource()}
*
* @param id
*/
protected Image(final String id)
{
super(id);
}
/**
* Constructs an image from an image resourcereference. That resource reference will bind its
* resource to the current SharedResources.
*
* If you are using non sticky session clustering and the resource reference is pointing to a
* Resource that isn't guaranteed to be on every server, for example a dynamic image or
* resources that aren't added with a IInitializer at application startup. Then if only that
* resource is requested from another server, without the rendering of the page, the image won't
* be there and will result in a broken link.
*
* @param id
* See Component
* @param resourceReference
* The shared image resource
*/
public Image(final String id, final ResourceReference resourceReference)
{
this(id, resourceReference, null);
}
/**
* Constructs an image from an image resourcereference. That resource reference will bind its
* resource to the current SharedResources.
*
* If you are using non sticky session clustering and the resource reference is pointing to a
* Resource that isn't guaranteed to be on every server, for example a dynamic image or
* resources that aren't added with a IInitializer at application startup. Then if only that
* resource is requested from another server, without the rendering of the page, the image won't
* be there and will result in a broken link.
*
* @param id
* See Component
* @param resourceReference
* The shared image resource
* @param resourceParameters
* The resource parameters
*/
public Image(final String id, final ResourceReference resourceReference,
PageParameters resourceParameters)
{
super(id);
setImageResourceReference(resourceReference, resourceParameters);
}
/**
* Constructs an image directly from an image resource.
*
* This one doesn't have the 'non sticky session clustering' problem that the ResourceReference
* constructor has. But this will result in a non 'stable' url and the url will have request
* parameters.
*
* @param id
* See Component
*
* @param imageResource
* The image resource
*/
public Image(final String id, final IResource imageResource)
{
super(id);
setImageResource(imageResource);
}
/**
* @see org.apache.wicket.Component#Component(String, IModel)
*/
public Image(final String id, final IModel<?> model)
{
super(id, model);
}
/**
* @param id
* See Component
* @param string
* Name of image
* @see org.apache.wicket.Component#Component(String, IModel)
*/
public Image(final String id, final String string)
{
this(id, new Model<>(string));
}
/**
* @see org.apache.wicket.IResourceListener#onResourceRequested()
*/
@Override
public void onResourceRequested()
{
localizedImageResource.onResourceRequested(null);
}
/**
* @param imageResource
* The new ImageResource to set.
*/
public void setImageResource(final IResource imageResource)
{
localizedImageResource.setResource(imageResource);
}
/**
* @param resourceReference
* The shared ImageResource to set.
*/
public void setImageResourceReference(final ResourceReference resourceReference)
{
localizedImageResource.setResourceReference(resourceReference);
}
/**
* @param resourceReference
* The shared ImageResource to set.
* @param parameters
* Set the resource parameters for the resource.
*/
public void setImageResourceReference(final ResourceReference resourceReference,
final PageParameters parameters)
{
localizedImageResource.setResourceReference(resourceReference, parameters);
}
/**
* @see org.apache.wicket.Component#setDefaultModel(org.apache.wicket.model.IModel)
*/
@Override
public Component setDefaultModel(IModel<?> model)
{
// Null out the image resource, so we reload it (otherwise we'll be
// stuck with the old model.
localizedImageResource.setResourceReference(null);
localizedImageResource.setResource(null);
return super.setDefaultModel(model);
}
/**
* @return Resource returned from subclass
*/
protected IResource getImageResource()
{
return localizedImageResource.getResource();
}
/**
* @return ResourceReference returned from subclass
*/
protected ResourceReference getImageResourceReference()
{
return localizedImageResource.getResourceReference();
}
/**
* @see org.apache.wicket.Component#initModel()
*/
@Override
protected IModel<?> initModel()
{
// Images don't support Compound models. They either have a simple
// model, explicitly set, or they use their tag's src or value
// attribute to determine the image.
return null;
}
/**
* @see org.apache.wicket.Component#onComponentTag(ComponentTag)
*/
@Override
protected void onComponentTag(final ComponentTag tag)
{
checkComponentTag(tag, "img");
super.onComponentTag(tag);
final IResource resource = getImageResource();
if (resource != null)
{
localizedImageResource.setResource(resource);
}
final ResourceReference resourceReference = getImageResourceReference();
if (resourceReference != null)
{
localizedImageResource.setResourceReference(resourceReference);
}
localizedImageResource.setSrcAttribute(tag);
if (shouldAddAntiCacheParameter())
{
addAntiCacheParameter(tag);
}
}
/**
* Adding an image to {@link org.apache.wicket.ajax.AjaxRequestTarget} most of the times mean that the image has
* changes and must be re-rendered.
* <p>
* With this method the user may change this default behavior for some of her images.
* </p>
*
* @return {@code true} to add the anti cache request parameter, {@code false} - otherwise
*/
protected boolean shouldAddAntiCacheParameter()
{
return getRequestCycle().find(AjaxRequestTarget.class) != null;
}
/**
* Adds random noise to the url every request to prevent the browser from caching the image.
*
* @param tag
*/
protected final void addAntiCacheParameter(final ComponentTag tag)
{
String url = tag.getAttributes().getString("src");
url = url + (url.contains("?") ? "&" : "?");
url = url + "antiCache=" + System.currentTimeMillis();
tag.put("src", url);
}
/**
* @see org.apache.wicket.Component#getStatelessHint()
*/
@Override
protected boolean getStatelessHint()
{
return (getImageResource() == null || getImageResource() == localizedImageResource.getResource()) &&
localizedImageResource.isStateless();
}
/**
* @see org.apache.wicket.Component#onComponentTagBody(MarkupStream, ComponentTag)
*/
@Override
public void onComponentTagBody(final MarkupStream markupStream, final ComponentTag openTag)
{
}
@Override
public boolean canCallListenerInterface(Method method)
{
boolean isResource = method != null && IResourceListener.class.isAssignableFrom(method.getDeclaringClass());
if (isResource && isVisibleInHierarchy())
{
// when the image data is requested we do not care if this component is enabled in
// hierarchy or not, only that it is visible
return true;
}
else
{
return super.canCallListenerInterface(method);
}
}
}