org.eclipse.jface.viewers.LabelProvider.java Source code

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Here is the source code for org.eclipse.jface.viewers.LabelProvider.java

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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
 * <code>toString</code> value for its text and <code>null</code> for its image.
 * <p>
 * This class may be used as is, or subclassed to provide richer labels.
 * Subclasses may override any of the following methods:
 * </p>
 * <ul>
 * <li><code>isLabelProperty</code></li>
 * <li><code>getImage</code></li>
 * <li><code>getText</code></li>
 * <li><code>dispose</code></li>
 * </ul>
 */
public class LabelProvider extends BaseLabelProvider implements ILabelProvider {

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

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

    /**
     * The <code>LabelProvider</code> implementation of this
     * <code>ILabelProvider</code> method returns the element's
     * <code>toString</code> 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<Object, String> 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<Object, Image> 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<Object, String> textFunction,
            Function<Object, Image> 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);
            }
        };
    }
}