src/main/java/de/uapcore/sudoku/SudokuTextField.java

/*
 * Copyright 2013 Mike Becker. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package de.uapcore.sudoku;

import javax.swing.*;
import java.awt.*;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

/**
 * A custom text field specifically for Sudoku number fields.
 */
public final class SudokuTextField extends JTextField {
    
    private boolean modified;
    
    public SudokuTextField() {
        setBorder(null);
        setBackground(Color.WHITE);
        
        setFont(new Font("Dialog", Font.PLAIN, 18));
        setHorizontalAlignment(JTextField.CENTER);
        
        Dimension dim = new Dimension(40,40);
        setPreferredSize(dim);
        setMinimumSize(dim);
        setMaximumSize(dim);
        
        addKeyListener(new KeyAdapter() {
            private void handle(KeyEvent e) {
                char c = e.getKeyChar();
                if (!e.isAltDown() && !e.isControlDown() &&
                        !Character.isISOControl(c)) {
                    // Perform clean input check
                    if (getText().length() > 0 && getSelectedText() == null) {
                        if (c != KeyEvent.CHAR_UNDEFINED) {
                            e.consume();
                        }
                    } else {
                        if (c < '1' || c > '9') {
                            e.consume();
                        } else {
                            setModified(true);
                        }
                    }
                } else {
                    // We can still be tricked by hotkeys, so do it the hard way
                    if (!getText().matches("^[1-9]$")) {
                        setText("");
                    }
                }
            }
            
            @Override
            public void keyPressed(KeyEvent e) {
                handle(e);
            }

            @Override
            public void keyTyped(KeyEvent e) {
                handle(e);
            }

            @Override
            public void keyReleased(KeyEvent e) {
                handle(e);
            }
            
        });
        addFocusListener(new FocusAdapter() {
            @Override
            public void focusGained(FocusEvent e) {
                selectAll();
            }
            @Override
            public void focusLost(FocusEvent e) {
                select(0, 0);
            }
        });
    }

    /**
     * Returns the current value in the field or zero if the field is empty.
     *
     * @return the number from 1 to 9 or zero if empty
     */
    public int getValue() {
        if (getText().isEmpty()) {
            return 0;
        } else {
            return Integer.parseInt(getText());
        }
    }

    /**
     * Sets the field's value.
     *
     * @param v the number from 1 to 9 or zero to clear the field
     * @throws IllegalArgumentException if v is not between 0 and 9
     */
    public void setValue(int v) {
        if (v == 0) {
            setText("");
        } else if (v > 0 && v < 10) {
            setText(String.valueOf(v));
        } else {
            throw new IllegalArgumentException(
                    "Sudoku numbers must be in range 0-9 (0 means 'not set')");
        }
    }

    /**
     * Sets the modified state of this field.
     *
     * Modified fields are displayed in blue color.
     *
     * @param modified a flag indicating whether this field is modified
     */
    public void setModified(boolean modified) {
        this.modified = modified;
        setForeground(modified?Color.BLUE:Color.BLACK);
    }

    /**
     * Checks whether this field is in modified state.
     *
     * @return true if this field is modified
     */
    public boolean isModified() {
        return modified;
    }
}