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/*
* Copyright 2000-2014 Vaadin Ltd.
*
* 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 com.vaadin.ui;
import java.util.Collections;
import java.util.Iterator;
/**
* Custom component provides a simple implementation of the {@link Component}
* interface to allow creating new UI components by composition of existing
* server-side components.
*
* <p>
* The component is used by inheriting the CustomComponent class and setting the
* composition root component. The composition root must be set with
* {@link #setCompositionRoot(Component)} before the CustomComponent is used,
* such as by adding it to a layout, so it is preferable to set it in the
* constructor.
* </p>
*
* <p>
* The composition root itself can contain more components. The advantage of
* wrapping it in a CustomComponent is that its details, such as interfaces, are
* hidden from the users of the component, thereby contributing to information
* hiding.
* </p>
*
* <p>
* The CustomComponent does not display the caption of the composition root, so
* if you want to have it shown in the layout where the custom component is
* contained, you need to set it as caption of the CustomComponent.
* </p>
*
* <p>
* The component expands horizontally and has undefined height by default.
* </p>
*
* @author Vaadin Ltd.
* @since 3.0
*/
@SuppressWarnings("serial")
public class CustomComponent extends AbstractComponent implements HasComponents {
/**
* The root component implementing the custom component.
*/
private Component root = null;
/**
* Constructs a new custom component.
*
* <p>
* Note that you must set the composition root before the component can be
* used, preferably in the constructor.
* </p>
*/
public CustomComponent() {
// Expand horizontally by default
setWidth(100, Unit.PERCENTAGE);
}
/**
* Constructs a new custom component.
*
* @param compositionRoot
* the root of the composition component tree. It must not be
* null.
*/
public CustomComponent(Component compositionRoot) {
this();
setCompositionRoot(compositionRoot);
}
/**
* Returns the composition root.
*
* @return the Component Composition root.
*/
protected Component getCompositionRoot() {
return root;
}
/**
* Sets the composition root for the component.
*
* <p>
* You must set the composition root must to a non-null value before the
* component can be used. You can change it later.
* </p>
*
* @param compositionRoot
* the root of the composition component tree.
*/
protected void setCompositionRoot(Component compositionRoot) {
if (compositionRoot != root) {
if (root != null && root.getParent() == this) {
// remove old component
root.setParent(null);
}
if (compositionRoot != null) {
// set new component
if (compositionRoot.getParent() != null) {
// If the component already has a parent, try to remove it
AbstractSingleComponentContainer
.removeFromParent(compositionRoot);
}
compositionRoot.setParent(this);
}
root = compositionRoot;
markAsDirty();
}
}
/* Basic component features ------------------------------------------ */
@Override
public Iterator<Component> iterator() {
if (getCompositionRoot() != null) {
return Collections.singletonList(getCompositionRoot()).iterator();
} else {
return Collections.<Component> emptyList().iterator();
}
}
/**
* Gets the number of contained components. Consistent with the iterator
* returned by {@link #getComponentIterator()}.
*
* @return the number of contained components (zero or one)
*/
public int getComponentCount() {
return (root != null ? 1 : 0);
}
}
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