org.eclipse.nebula.widgets.nattable.core/src/org/eclipse/nebula/widgets/nattable/filterrow/combobox/FilterRowComboBoxCellEditor.java

/*******************************************************************************
 * Copyright (c) 2013, 2020 Dirk Fauth and others.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    Dirk Fauth <dirk.fauth@googlemail.com> - initial API and implementation
 *    Ryan McHale <rpmc22@gmail.com> - Bug 484716
 *******************************************************************************/
package org.eclipse.nebula.widgets.nattable.filterrow.combobox;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.nebula.widgets.nattable.data.convert.ConversionFailedException;
import org.eclipse.nebula.widgets.nattable.edit.EditConstants;
import org.eclipse.nebula.widgets.nattable.edit.editor.ComboBoxCellEditor;
import org.eclipse.nebula.widgets.nattable.edit.editor.IComboBoxDataProvider;
import org.eclipse.nebula.widgets.nattable.selection.SelectionLayer.MoveDirectionEnum;
import org.eclipse.nebula.widgets.nattable.widget.EditModeEnum;
import org.eclipse.nebula.widgets.nattable.widget.NatCombo;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;

/**
 * Specialisation of ComboBoxCellEditor that can only be created using an
 * IComboBoxDataProvider. Will show a multiselect combobox with checkboxes and
 * uses the FilterNatCombo as underlying control.
 *
 * @see FilterRowComboBoxDataProvider
 */
public class FilterRowComboBoxCellEditor extends ComboBoxCellEditor {

    private static final Log log = LogFactory.getLog(FilterRowComboBoxCellEditor.class);

    /**
     * This object remembers the current value in the editor. This is necessary
     * to avoid double commits on closing the editor again.
     * <p>
     * Per default editors commit their values prior to closing them. The commit
     * call is performed by various actions that get triggered when the editor
     * losses focus. As this editor is configured to commit the value on each
     * click of a checkbox, we avoid committing the value again on closing.
     */
    private Object currentCanonicalValue = null;

    /**
     * Create a new {@link FilterRowComboBoxCellEditor} based on the given
     * {@link IComboBoxDataProvider}, showing the default number of items in the
     * dropdown of the combo.
     *
     * @param dataProvider
     *            The {@link IComboBoxDataProvider} that is responsible for
     *            populating the items to the dropdown box.
     */
    public FilterRowComboBoxCellEditor(IComboBoxDataProvider dataProvider) {
        this(dataProvider, NatCombo.DEFAULT_NUM_OF_VISIBLE_ITEMS);
    }

    /**
     * Create a new {@link FilterRowComboBoxCellEditor} based on the given
     * {@link IComboBoxDataProvider}.
     *
     * @param dataProvider
     *            The {@link IComboBoxDataProvider} that is responsible for
     *            populating the items to the dropdown box.
     * @param maxVisibleItems
     *            The maximum number of items the drop down will show before
     *            introducing a scroll bar.
     */
    public FilterRowComboBoxCellEditor(IComboBoxDataProvider dataProvider, int maxVisibleItems) {
        super(dataProvider, maxVisibleItems);
        this.multiselect = true;
        this.useCheckbox = true;
    }

    @Override
    public NatCombo createEditorControl(Composite parent) {
        int style = SWT.READ_ONLY | SWT.MULTI | SWT.CHECK;
        final FilterNatCombo combo = this.iconImage == null
                ? new FilterNatCombo(parent, this.cellStyle, this.maxVisibleItems, style, this.showDropdownFilter)
                : new FilterNatCombo(parent, this.cellStyle, this.maxVisibleItems, style, this.iconImage, this.showDropdownFilter);

        combo.setCursor(new Cursor(Display.getDefault(), SWT.CURSOR_IBEAM));

        combo.setMultiselectValueSeparator(this.multiselectValueSeparator);
        combo.setMultiselectTextBracket(this.multiselectTextPrefix, this.multiselectTextSuffix);

        addNatComboListener(combo);

        // additionally add the ICheckStateListener so on changing the value of
        // the select all item the change is also committed
        combo.addCheckStateListener(event -> {
            if (event.getChecked()) {
                setCanonicalValue(EditConstants.SELECT_ALL_ITEMS_VALUE);
            }
            commit(MoveDirectionEnum.NONE,
                    (!FilterRowComboBoxCellEditor.this.multiselect
                            && FilterRowComboBoxCellEditor.this.editMode == EditModeEnum.INLINE));
        });

        return combo;
    }

    @Override
    public void setCanonicalValue(Object canonicalValue) {
        this.currentCanonicalValue = canonicalValue;
        super.setCanonicalValue(canonicalValue);
    }

    @Override
    public boolean commit(MoveDirectionEnum direction, boolean closeAfterCommit) {
        // If the editor should be closed after commit, we first need to ensure
        // if the value has changed since the last commit.
        // This needs to be done because in this filter combo box, every
        // selection immediately causes a commit, which results in applying a
        // filter. If the combo box is now closed because of losing the focus,
        // the value gets committed again, which again results in filtering,
        // which will lead to exceptions because the states are not synchronous
        // anymore.
        if (!isClosed()) {
            try {
                // always do the conversion
                Object canonicalValue = getCanonicalValue();
                if ((canonicalValue != null && this.currentCanonicalValue == null)
                        || (canonicalValue == null && this.currentCanonicalValue != null)
                        || (canonicalValue != null
                                && this.currentCanonicalValue != null
                                && !canonicalValue.equals(this.currentCanonicalValue))) {
                    if (super.commit(direction, closeAfterCommit)) {
                        this.currentCanonicalValue = canonicalValue;
                        return true;
                    }
                } else {
                    // the values are the same so it is not necessary to commit
                    // again
                    if (closeAfterCommit) {
                        close();
                    }
                    return true;
                }
            } catch (ConversionFailedException e) {
                // do nothing as exceptions caused by conversion are handled
                // already. we just need this catch block for stopping the
                // process if conversion failed with an exception
            } catch (Exception e) {
                // if another exception occured that wasn't thrown by us, it
                // should at least be logged without killing the whole
                // application
                log.error("Error on updating cell value: " + e.getLocalizedMessage(), e); //$NON-NLS-1$
            }
        }
        return false;
    }

}