// Copyright 2004, 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.form;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.tapestry.IForm;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.Tapestry;
/**
* A special type of form component that is used to contain {@link Radio}components. The Radio and
* {@link Radio}group components work together to update a property of some other object, much like
* a more flexible version of a {@link PropertySelection}. [ <a
* href="../../../../../ComponentReference/RadioGroup.html">Component Reference </a>]
*
* @author Howard Lewis Ship
*/
public abstract class RadioGroup extends AbstractFormComponent
{
// Cached copy of the value from the selectedBinding
private Object _selection;
// The value from the HTTP request indicating which
// Radio was selected by the user.
private int _selectedOption;
private boolean _rewinding;
private boolean _rendering;
private int _nextOptionId;
/**
* A <code>RadioGroup</code> places itself into the {@link IRequestCycle}as an attribute, so
* that its wrapped {@link Radio}components can identify thier state.
*/
private static final String ATTRIBUTE_NAME = "org.apache.tapestry.active.RadioGroup";
public static RadioGroup get(IRequestCycle cycle)
{
return (RadioGroup) cycle.getAttribute(ATTRIBUTE_NAME);
}
public int getNextOptionId()
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "nextOptionId");
return _nextOptionId++;
}
/**
* Used by {@link Radio}components wrapped by this <code>RadioGroup</code> to see if the
* group as a whole is disabled.
*/
public abstract boolean isDisabled();
public boolean isRewinding()
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "rewinding");
return _rewinding;
}
/**
* Returns true if the value is equal to the current selection for the group. This is invoked by
* a {@link Radio}during rendering to determine if it should be marked 'checked'.
*/
public boolean isSelection(Object value)
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "selection");
if (_selection == value)
return true;
if (_selection == null || value == null)
return false;
return _selection.equals(value);
}
/**
* Invoked by the {@link Radio}which is selected to update the property bound to the selected
* parameter.
*/
public void updateSelection(Object value)
{
getBinding("selected").setObject(value);
}
/**
* Used by {@link Radio}components when rewinding to see if their value was submitted.
*/
public boolean isSelected(int option)
{
return _selectedOption == option;
}
/**
* Doesn't actual render an HTML element as there is no direct equivalent for an HTML element. A
* <code>RadioGroup</code> component exists to organize the {@link Radio}components it wraps
* (directly or indirectly). A {@link Radio}can finds its {@link RadioGroup}as a
* {@link IRequestCycle}attribute.
*/
protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
{
IForm form = getForm(cycle);
if (cycle.getAttribute(ATTRIBUTE_NAME) != null)
throw new ApplicationRuntimeException(Tapestry.getMessage("RadioGroup.may-not-nest"),
this, null, null);
// It isn't enough to know whether the cycle in general is rewinding, need to know
// specifically if the form which contains this component is rewinding.
_rewinding = form.isRewinding();
// Used whether rewinding or not.
String name = form.getElementId(this);
cycle.setAttribute(ATTRIBUTE_NAME, this);
// When rewinding, find out which (if any) radio was selected by
// the user.
if (_rewinding)
{
String value = cycle.getParameter(name);
if (value == null)
_selectedOption = -1;
else
_selectedOption = Integer.parseInt(value);
}
try
{
_rendering = true;
_nextOptionId = 0;
// For rendering, the Radio components need to know what the current
// selection is, so that the correct one can mark itself 'checked'.
if (!_rewinding)
_selection = getBinding("selected").getObject();
renderBody(writer, cycle);
}
finally
{
_rendering = false;
_selection = null;
}
cycle.removeAttribute(ATTRIBUTE_NAME);
}
}