// Copyright 2005 The Apache Software Foundation
//
// 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 org.apache.tapestry.util;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.hivemind.Locatable;
import org.apache.hivemind.Location;
import org.apache.hivemind.Resource;
import org.apache.hivemind.util.Defense;
import org.apache.tapestry.IAsset;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.PageRenderSupport;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.asset.AssetFactory;
import org.apache.tapestry.asset.PrivateAsset;
/**
* Implementation of {@link org.apache.tapestry.PageRenderSupport}. The
* {@link org.apache.tapestry.html.Body} component uses an instance of this class.
*
* @author Howard M. Lewis Ship
* @since 4.0
*/
public class PageRenderSupportImpl implements Locatable, PageRenderSupport
{
private final AssetFactory _assetFactory;
private final Location _location;
// Lines that belong inside the onLoad event handler for the <body> tag.
private StringBuffer _initializationScript;
// Any other scripting desired
private StringBuffer _bodyScript;
// Contains text lines related to image initializations
private StringBuffer _imageInitializations;
/**
* Map of URLs to Strings (preloaded image references).
*/
private Map _imageMap;
/**
* List of included scripts. Values are Strings.
*
* @since 1.0.5
*/
private List _externalScripts;
private final IdAllocator _idAllocator;
private final String _preloadName;
public PageRenderSupportImpl(AssetFactory assetFactory, String namespace, Location location)
{
Defense.notNull(assetFactory, "assetService");
_assetFactory = assetFactory;
_location = location;
_idAllocator = new IdAllocator(namespace);
_preloadName = (namespace.equals("") ? "tapestry" : namespace) + "_preload";
}
/**
* Returns the location, which may be used in error messages. In practical terms, this is the
* location of the {@link org.apache.tapestry.html.Body} component.
*/
public Location getLocation()
{
return _location;
}
public String getPreloadedImageReference(String URL)
{
if (_imageMap == null)
_imageMap = new HashMap();
String reference = (String) _imageMap.get(URL);
if (reference == null)
{
int count = _imageMap.size();
String varName = _preloadName + "[" + count + "]";
reference = varName + ".src";
if (_imageInitializations == null)
_imageInitializations = new StringBuffer();
_imageInitializations.append(" ");
_imageInitializations.append(varName);
_imageInitializations.append(" = new Image();\n");
_imageInitializations.append(" ");
_imageInitializations.append(reference);
_imageInitializations.append(" = \"");
_imageInitializations.append(URL);
_imageInitializations.append("\";\n");
_imageMap.put(URL, reference);
}
return reference;
}
public void addBodyScript(String script)
{
if (_bodyScript == null)
_bodyScript = new StringBuffer(script.length());
_bodyScript.append(script);
}
public void addInitializationScript(String script)
{
if (_initializationScript == null)
_initializationScript = new StringBuffer(script.length() + 1);
_initializationScript.append(script);
_initializationScript.append('\n');
}
public void addExternalScript(Resource scriptLocation)
{
if (_externalScripts == null)
_externalScripts = new ArrayList();
if (_externalScripts.contains(scriptLocation))
return;
// Record the Resource so we don't include it twice.
_externalScripts.add(scriptLocation);
}
public String getUniqueString(String baseValue)
{
return _idAllocator.allocateId(baseValue);
}
private void writeExternalScripts(IMarkupWriter writer, IRequestCycle cycle)
{
int count = Tapestry.size(_externalScripts);
for (int i = 0; i < count; i++)
{
Resource scriptLocation = (Resource) _externalScripts.get(i);
IAsset asset = _assetFactory.createAsset(scriptLocation, null);
String url = asset.buildURL(cycle);
// Note: important to use begin(), not beginEmpty(), because browser don't
// interpret <script .../> properly.
writer.begin("script");
writer.attribute("language", "JavaScript");
writer.attribute("type", "text/javascript");
writer.attribute("src", url);
writer.end();
writer.println();
}
}
/**
* Writes a single large JavaScript block containing:
* <ul>
* <li>Any image initializations (via {@link #getPreloadedImageReference(String)})
* <li>Any included scripts (via {@link #addExternalScript(Resource)})
* <li>Any contributions (via {@link #addBodyScript(String)})
* </ul>
*
* @see #writeInitializationScript(IMarkupWriter)
*/
public void writeBodyScript(IMarkupWriter writer, IRequestCycle cycle)
{
if (!Tapestry.isEmpty(_externalScripts))
writeExternalScripts(writer, cycle);
if (!(any(_bodyScript) || any(_imageInitializations)))
return;
writer.begin("script");
writer.attribute("language", "JavaScript");
writer.attribute("type", "text/javascript");
writer.printRaw("<!--");
if (any(_imageInitializations))
{
writer.printRaw("\n\nvar " + _preloadName + " = new Array();\n");
writer.printRaw("if (document.images)\n");
writer.printRaw("{\n");
writer.printRaw(_imageInitializations.toString());
writer.printRaw("}\n");
}
if (any(_bodyScript))
{
writer.printRaw("\n\n");
writer.printRaw(_bodyScript.toString());
}
writer.printRaw("\n\n// -->");
writer.end();
}
/**
* Writes any image initializations; this should be invoked at the end of the render, after all
* the related HTML will have already been streamed to the client and parsed by the web browser.
* Earlier versions of Tapestry uses a <code>window.onload</code> event handler.
*/
public void writeInitializationScript(IMarkupWriter writer)
{
if (!any(_initializationScript))
return;
writer.begin("script");
writer.attribute("language", "JavaScript");
writer.attribute("type", "text/javascript");
writer.printRaw("<!--\n");
writer.printRaw(_initializationScript.toString());
writer.printRaw("\n// -->");
writer.end();
}
private boolean any(StringBuffer buffer)
{
return buffer != null && buffer.length() > 0;
}
}