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

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

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/*******************************************************************************
 * Copyright (c) 2006, 2015 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
 *     Tom Schindl <tom.schindl@bestsolution.at> - initial API and implementation
 *                                       fix for bug 163317, 201905
 *     Ralf Ebert - bug 294738
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 475689
 *******************************************************************************/

package org.eclipse.jface.viewers;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.util.Policy;
import org.eclipse.swt.widgets.Widget;

/**
 * Instances of this class represent a column of a {@link ColumnViewer}. Label
 * providers and editing support can be configured for each column separately.
 * Concrete subclasses of {@link ColumnViewer} should implement a matching
 * concrete subclass of {@link ViewerColumn}.
 *
 * @since 3.3
 *
 */
public abstract class ViewerColumn {

    private CellLabelProvider labelProvider;

    static String COLUMN_VIEWER_KEY = Policy.JFACE + ".columnViewer";//$NON-NLS-1$

    private EditingSupport editingSupport;

    private ILabelProviderListener listener;

    private boolean listenerRegistered = false;

    private ColumnViewer viewer;

    /**
     * Create a new instance of the receiver at columnIndex.
     *
     * @param viewer
     *            the viewer the column is part of
     * @param columnOwner
     *            the widget owning the viewer in case the widget has no columns
     *            this could be the widget itself
     */
    protected ViewerColumn(final ColumnViewer viewer, Widget columnOwner) {
        this.viewer = viewer;
        columnOwner.setData(ViewerColumn.COLUMN_VIEWER_KEY, this);
        this.listener = viewer::handleLabelProviderChanged;
        columnOwner.addDisposeListener(e -> handleDispose(viewer));
    }

    /**
     * Return the label provider for the receiver.
     *
     * @return ViewerLabelProvider
     */
    /* package */CellLabelProvider getLabelProvider() {
        return labelProvider;
    }

    /**
     * Set the label provider for the column. Subclasses may extend but must
     * call the super implementation.
     *
     * @param labelProvider
     *            the new {@link CellLabelProvider}
     */
    public void setLabelProvider(CellLabelProvider labelProvider) {
        setLabelProvider(labelProvider, true);
    }

    /**
     * @param labelProvider
     * @param registerListener
     */
    /* package */void setLabelProvider(CellLabelProvider labelProvider, boolean registerListener) {
        if (listenerRegistered && this.labelProvider != null) {
            this.labelProvider.removeListener(listener);
            listenerRegistered = false;
            if (registerListener) {
                this.labelProvider.dispose(viewer, this);
            }
        }

        this.labelProvider = labelProvider;

        if (registerListener) {
            this.labelProvider.initialize(viewer, this);
            this.labelProvider.addListener(listener);
            listenerRegistered = true;
        }
    }

    /**
     * Return the editing support for the receiver.
     *
     * @return {@link EditingSupport}
     */
    /* package */EditingSupport getEditingSupport() {
        return editingSupport;
    }

    /**
     * Set the editing support. Subclasses may extend but must call the super
     * implementation.
     * <p>
     * Users setting up an editable {@link TreeViewer} or {@link TableViewer} with more than 1 column <b>have</b>
     * to pass the SWT.FULL_SELECTION style bit when creating the viewer
     * </p>
     * @param editingSupport
     *            The {@link EditingSupport} to set.
     */
    public void setEditingSupport(EditingSupport editingSupport) {
        this.editingSupport = editingSupport;
    }

    /**
     * Refresh the cell for the given columnIndex. <strong>NOTE:</strong>the
     * {@link ViewerCell} provided to this method is no longer valid after this
     * method returns. Do not cache the cell for future use.
     *
     * @param cell
     *            {@link ViewerCell}
     */
    /* package */void refresh(ViewerCell cell) {
        CellLabelProvider labelProvider = getLabelProvider();
        if (labelProvider == null) {
            Assert.isTrue(false, "Column " + cell.getColumnIndex() + //$NON-NLS-1$
                    " has no label provider."); //$NON-NLS-1$
        }
        labelProvider.update(cell);
    }

    /**
     * Disposes of the label provider (if set), unregisters the listener and
     * nulls the references to the label provider and editing support. This
     * method is called when the underlying widget is disposed. Subclasses may
     * extend but must call the super implementation.
     */
    protected void handleDispose() {
        boolean disposeLabelProvider = listenerRegistered;
        CellLabelProvider cellLabelProvider = labelProvider;
        setLabelProvider(null, false);
        if (disposeLabelProvider) {
            cellLabelProvider.dispose(viewer, this);
        }
        editingSupport = null;
        listener = null;
        viewer = null;
    }

    private void handleDispose(ColumnViewer viewer) {
        handleDispose();
        viewer.clearLegacyEditingSetup();
    }

    /**
     * Returns the viewer of this viewer column.
     *
     * @return Returns the viewer.
     *
     * @since 3.4
     */
    public ColumnViewer getViewer() {
        return viewer;
    }
}