modeler/cayenne-modeler/src/main/java/org/apache/cayenne/swing/ComboSelectionBinding.java

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 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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 *    https://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cayenne.swing;

import java.awt.Color;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemListener;

import javax.swing.JComboBox;
import javax.swing.JComponent;

import org.apache.cayenne.modeler.dialog.validator.ValidatorDialog;
import org.apache.cayenne.modeler.undo.JComboBoxUndoListener;
import org.apache.cayenne.validation.ValidationException;

/**
 */
public class ComboSelectionBinding extends BindingBase {

    protected JComboBox comboBox;

    protected Color defaultBGColor;
    protected Color errorColor;
    protected String defaultToolTip;
    protected String noSelectionValue;

    /**
     * Binds to update model for a combo box selection events. For editable combo boxes
     * model is updated whenever a new value is entered.
     */
    public ComboSelectionBinding(JComboBox comboBox, String expression,
            String noSelectionValue) {
        super(expression);
        this.comboBox = comboBox;
        this.noSelectionValue = noSelectionValue;

        // insert no selection value as first item in the combobox if it is not there
        if (noSelectionValue != null
                && (comboBox.getItemCount() == 0 || comboBox.getItemAt(0) != noSelectionValue)) {

            comboBox.insertItemAt(noSelectionValue, 0);
        }

        comboBox.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                if (!modelUpdateDisabled) {
                    updateModel();
                }
            }
        });

        // init error colors
        initComponentDefaults();
    }

    protected void initComponentDefaults() {
        this.errorColor = ValidatorDialog.WARNING_COLOR;

        if (comboBox.getEditor() != null) {

            Component editor = comboBox.getEditor().getEditorComponent();
            if (editor instanceof JComponent) {
                JComponent jEditor = (JComponent) editor;
                this.defaultBGColor = jEditor.getBackground();
                this.defaultToolTip = jEditor.getToolTipText();
            }
        }
    }

    public void updateView() {
        Object value = getValue();
        modelUpdateDisabled = true;
        try {
            clear();
            ItemListener[] listeners = comboBox.getItemListeners();
            for (ItemListener itemListener : listeners) {
                if (itemListener instanceof JComboBoxUndoListener) {
                    //in order not to add event to undo list
                    ((JComboBoxUndoListener) itemListener).setIsUserAction(false);
                }
            }
            if (value != null) {
                this.comboBox.setSelectedItem(value.toString());
            }
            else if (noSelectionValue != null) {
                this.comboBox.setSelectedItem(noSelectionValue);
            }
            else {
                this.comboBox.setSelectedIndex(-1);
            }
        }
        finally {
            modelUpdateDisabled = false;
        }
    }

    protected void updateModel() {
        try {
            Object value = comboBox.getSelectedItem();
            if (noSelectionValue != null && noSelectionValue.equals(value)) {
                value = null;
            }
            setValue(value);
            clear();
        }
        catch (ValidationException vex) {
            initWarning(vex.getLocalizedMessage());
        }
    }

    public Component getView() {
        return comboBox;
    }

    protected void clear() {
        if (comboBox.getEditor() != null) {

            Component editor = comboBox.getEditor().getEditorComponent();
            if (editor instanceof JComponent) {
                JComponent jEditor = (JComponent) editor;
                jEditor.setBackground(defaultBGColor);
                jEditor.setToolTipText(defaultToolTip);
            }
        }
    }

    protected void initWarning(String message) {
        if (comboBox.getEditor() != null) {

            Component editor = comboBox.getEditor().getEditorComponent();
            if (editor instanceof JComponent) {
                JComponent jEditor = (JComponent) editor;
                jEditor.setBackground(errorColor);
                jEditor.setToolTipText(message);
            }
        }
    }
}