/*
 * [ShroudedImage.java]
 *
 * Summary: Displays a text field as a png, useful for masking email addresses.
 *
 * Copyright: (c) 2005-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.7 2009-04-04 get rid of artifacts on screen. Suggest lower case filename.
 */
package com.mindprod.masker;

import javax.imageio.ImageIO;
import javax.swing.JFileChooser;
import javax.swing.JPanel;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.prefs.Preferences;

import static java.lang.System.*;

/**
 * Displays a text field as a png, useful for masking email addresses.
 * <p/>
 * Displays both on the screen and saves as a PNG.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.7 2009-04-04 get rid of artifacts on screen. Suggest lower case filename.
 * @since 2005
 */
final class ShroudedImage extends JPanel
    {
    /**
     * the text to be displayed
     */
    private String text;

    /**
     * height of text above baseline
     */
    private int ascent;

    /**
     * height of image
     */
    private int height;

    /**
     * width of image
     */
    private int width;

    /**
     * constructor
     *
     * @param text the text to display
     */
    public ShroudedImage( String text )
        {
        // This makes no sense, but it only works if set false.
        this.setOpaque( false );
        setText( text );
        }

    /**
     * calculate size needed for image, and refresh it.
     */
    private void refresh()
        {
        if ( this.text == null )
            {
            return;
            }
        Font font = this.getFont();
        FontMetrics fm = this.getFontMetrics( font );
        width = fm.stringWidth( text );
        // ideally no space at all around text.
        // FontMetrics getAscent getHeight, getDescent only approximate, have a
        // lot of white space.
        // We want more accurate LineMetrics.
        // We need a Graphics object in order to do line metrics.
        // This seems like over kill but here we go:
        // create a BufferedImage
        BufferedImage bufferedImage = new BufferedImage( 200
                /* dummy */,
                200
                /* dummy */,
                BufferedImage.TYPE_4BYTE_ABGR_PRE );
        Graphics2D g2d = bufferedImage.createGraphics();
        FontRenderContext fr = g2d.getFontRenderContext();
        LineMetrics lm = font.getLineMetrics( text, fr );
        ascent = ( int ) ( lm.getAscent() + .5 );
        height = ( int ) ( lm.getDescent() + lm.getAscent() + .5 );
        Dimension d = new Dimension( width, height );
        this.setPreferredSize( d );
        this.setMinimumSize( d );
        this.setMaximumSize( d );
        invalidate();
        repaint();
        }

    /**
     * draws the text
     *
     * @param g graphics region where we paint
     */
    public void paintComponent( Graphics g )
        {
        // if call super.paintComponent generates artifacts -- the default rendering of a JPanel which we do not want.
        // super.paintComponent( g );
        Graphics2D g2d = ( Graphics2D ) g;
        g2d.addRenderingHints( new RenderingHints( RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON ) );
        // we don't clear the background, but oddly all works ok.
        g2d.setFont( this.getFont() );
        g2d.setColor( this.getForeground() );
        // x,y is bottom left corner of text
        g2d.drawString( text, 0, ascent );   // y increases going down.
        }

    /**
     * save current image as a png.
     *
     * @param saveName file name to save under, without directory.
     */
    public void saveImage( String saveName )
        {
        // ask user where to save.
        // persisted in registry directory last used
        Preferences userPrefs =
                Preferences.userRoot().node( "/com/mindprod/masker" );
        final File suggestedFile =
                new File( userPrefs.get( "SAVEDIR", "C:" ), saveName );
        JFileChooser fc = new JFileChooser();
        fc.setSelectedFile( suggestedFile );
        // filter out all but PNG file from view
        fc.addChoosableFileFilter( new PNGFileFilter() );
        int result = fc.showSaveDialog( this );
        switch ( result )
            {
            case JFileChooser.APPROVE_OPTION:
                final File file = fc.getSelectedFile();
                try
                    {
                    // repaint onto a BufferedImage
                    BufferedImage bufferedImage =
                            new BufferedImage( width,
                                    height,
                                    BufferedImage.TYPE_4BYTE_ABGR_PRE );
                    Graphics2D g2d = bufferedImage
                            .createGraphics();
                    // redraw using our paintComponent
                    paintComponent( g2d );
                    // write out the BufferedImage as a PNG
                    ImageIO.write( bufferedImage, "png"
                            , file );
                    }
                catch ( IOException e )
                    {
                    err.println( "image not saved successfully" );
                    }
                // save same directory for next time.
                // persisted in registry directory last used
                userPrefs.put( "SAVEDIR", fc.getCurrentDirectory()
                        .getAbsolutePath() );
                break;
            case JFileChooser.CANCEL_OPTION:
            case JFileChooser.ERROR_OPTION:
                break;
            default:
            }
        }

    /**
     * overide standard setFont
     *
     * @param font new font to use in display
     */
    public void setFont( Font font )
        {
        super.setFont( font );
        refresh();
        }

    /**
     * Sets text to be displayed
     *
     * @param text Text to display
     */
    public void setText( String text )
        {
        this.text = text;
        refresh();
        }
    }