org.eclipse.jface.viewers.LabelProvider Maven / Gradle / Ivy

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/*******************************************************************************
 * Copyright (c) 2000, 2014 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.viewers;

import java.util.Objects;
import java.util.function.Function;

import org.eclipse.swt.graphics.Image;

/**
 * A label provider implementation which, by default, uses an element's
 * toString value for its text and null for its image.
 * 
 * This class may be used as is, or subclassed to provide richer labels.
 * Subclasses may override any of the following methods:
 * 
 * 
 * isLabelProperty
 * getImage
 * getText
 * dispose
 * 
 */
public class LabelProvider extends BaseLabelProvider implements ILabelProvider {

	/**
	 * Creates a new label provider.
	 */
	public LabelProvider() {
	}

	/**
	 * The LabelProvider implementation of this
	 * ILabelProvider method returns null.
	 * Subclasses may override.
	 */
	@Override
	public Image getImage(Object element) {
		return null;
	}

	/**
	 * The LabelProvider implementation of this
	 * ILabelProvider method returns the element's
	 * toString string. Subclasses may override.
	 */
	@Override
	public String getText(Object element) {
		return element == null ? "" : element.toString();//$NON-NLS-1$
	}

	/**
	 * Creates a {@link LabelProvider} which implements the {@link #getText} method
	 * by calling the argument function.
	 *
	 * @param textFunction the function which returns the text
	 * @return The new LabelProvider
	 * @since 3.19
	 */
	public static LabelProvider createTextProvider(Function textFunction) {
		Objects.requireNonNull(textFunction);
		return new LabelProvider() {
			@Override
			public String getText(Object e) {
				return textFunction.apply(e);
			}
		};
	}

	/**
	 * Creates a {@link LabelProvider} which implements the {@link #getImage} method
	 * by calling the argument function.
	 *
	 * @param imageFunction the function which returns the image
	 * @return The new LabelProvider
	 * @since 3.19
	 */
	public static LabelProvider createImageProvider(Function imageFunction) {
		Objects.requireNonNull(imageFunction);
		return new LabelProvider() {
			@Override
			public Image getImage(Object e) {
				return imageFunction.apply(e);
			}
		};
	}

	/**
	 * Creates a {@link LabelProvider} which implements both the {@link #getText}
	 * and {@link #getImage} methods by calling the argument functions.
	 *
	 * @param textFunction  the function which returns the text
	 * @param imageFunction the function which returns the image
	 * @return The new LabelProvider
	 * @since 3.19
	 */
	public static LabelProvider createTextImageProvider(Function textFunction,
			Function imageFunction) {
		Objects.requireNonNull(textFunction);
		Objects.requireNonNull(imageFunction);
		return new LabelProvider() {
			@Override
			public String getText(Object e) {
				return textFunction.apply(e);
			}
			@Override
			public Image getImage(Object e) {
				return imageFunction.apply(e);
			}
		};
	}
}