PC Plus SuperCD (UK) 1997 May/PC Plus Super CD Issue 127 (May 1997).iso/vcafe/samples.bin/Calendar.java

Java Source | 1996-09-04 | 17.7 KB | 617 lines

/*
 * Title: Calendar
 * Type: Applet
 * Source: Calendar.java
 * Application Description: Display a calendar window with the
 * month/year selected by the user.  When a date is selected,
 * a scrolling text box is displayed at the top along with the
 * event information for that date. Event information is input
 * and extracted from HTML. The format for the "date:event"
 * HTML is the following:
 *
 *      param name=EVENT1 value="01/23/96:January 23, 1996 - Bake Sale"
 *      param name=EVENT2 value="01/30/96:January 30, 1996 - Ski Vacation"
 *
 * NOTE:  The date and event string information are separated by a
 * colon (:); the format for the date MUST be MM/DD/YY.
 *
 * Symantec Corporation.
 */

import java.applet.Applet;
import java.awt.*;
import java.awt.Font;
import java.util.Date;
import java.util.Hashtable;
import java.lang.String;

/**
 * The main applet class
 */

public class Calendar extends Applet implements Runnable
{
        Button myButton[];                  // The calendar date buttons
        Image bannerText;                   // The banner text display object
        MyCanvas textCanvas;                // The banner text display object
        boolean loaded = true;
        Graphics textGC;

        //TextField date;                     // Date display text field
        int thismonth;                      // App. variable
        int thisyear;                       // App. variable
        int days;                           // App. variable
        int dayselected;                    // App. variable
        Date dateSelected;                  // User-selected Date object
        int buttonShift;                    // Used to determine what day the
                                            // 1st of the month falls on

        Hashtable eventHash;                // Used to track date/event combinations

        //Thread related variables.
        Thread bannerThread;                // The main banner thread
        int maxWidth;                       // The width of the banner window
        int maxHeight;                      // The height of the banner window
        int bannerHeight = 20;              // The height of the banner text
           public String message;              // The string displayed on the banner
           int msgX = 0;                       // X-coordinate of the banner string
           int msgY = 0;                       // Y-coordinate of the banner string
           int msgWidth = 0;                   // This is the width of the message in pixels
           public Dimension lastS = new Dimension(1, 1);
           public Font msgFont;                // The font used in the banner
           static boolean loadedtext = true;

        /**
         *  Set up the three main panels (top,middle,lower) along with the
         *  UI components (calendar buttons, etc.)
         */

        public void init()
        {
            message = "Welcome to the Java Calendar!!!";

            eventHash = new Hashtable();
            getParamData();

            setLayout(new BorderLayout());

            //Set up the banner...
            bannerText = createImage(300,20);
            textGC = bannerText.getGraphics();
            textGC.setColor(Color.blue);
            textGC.fillRect(4, 4, 300, 20);
            textGC.setColor(Color.white);

            textCanvas = new MyCanvas(bannerText);
            textCanvas.resize(300, 25);

            //Set up the center (calendar) panel...
            Label sunday, monday, tuesday, wednesday, thursday, friday, saturday;
            sunday = new Label("Sun");
            monday = new Label("Mon");
            tuesday = new Label("Tue");
            wednesday = new Label("Wed");
            thursday = new Label("Thu");
            friday = new Label("Fri");
            saturday = new Label("Sat");

            Panel datePanel = new Panel();
            datePanel.setLayout(new GridLayout(7, 7));

            datePanel.add(sunday);
            datePanel.add(monday);
            datePanel.add(tuesday);
            datePanel.add(wednesday);
            datePanel.add(thursday);
            datePanel.add(friday);
            datePanel.add(saturday);

            myButton=new Button[42];
            for(int i = 0; i < 42; i++)
            {
              myButton[i] = new Button("");
              datePanel.add(myButton[i]);
            }

            //{{INIT_CONTROLS
        setLayout(new FlowLayout(FlowLayout.CENTER,5,5));
        addNotify();
        resize(430,270);
        selPanel = new java.awt.Panel();
        selPanel.setLayout(new FlowLayout(FlowLayout.CENTER,5,5));
        selPanel.reshape(3,76,321,54);
        selPanel.setFont(new Font("Dialog", Font.PLAIN, 12));
        add(selPanel);
        leftButton = new java.awt.Button("<<<");
        leftButton.reshape(18,18,63,26);
        selPanel.add(leftButton);
        date = new java.awt.TextField(15);
        date.reshape(94,18,130,26);
        selPanel.add(date);
        rightButton = new java.awt.Button(">>>");
        rightButton.reshape(237,18,63,26);
        selPanel.add(rightButton);
        //}}

            date.setEditable(false);

            add("North", textCanvas);
            add("Center", datePanel);

            textCanvas.resize(299, 25);
            datePanel.resize(299, 225);
            selPanel.resize(299, 25);
        }

        /**
         * Find out today's date and set up the calendar to display the correct
         * month and year
         */

        public void start()
        {
            Date todaydate = new Date();
            setMonthString(todaydate);
            setCalendar(todaydate);

            //Establish the font size and characteristics for the banner
            CreateBannerParams();

            bannerThread = new Thread(this);
            bannerThread.start();
        }


        /**
         * The paint function is used to draw the text string which is
         * displayed along the top of the calendar.
         */

        public void paint(Graphics g)
        {
            g.drawImage(bannerText, 0, 0, this);
        }

        /**
         * Handle the events of the date-selection buttons as well as the
         * buttons corresponding to specific days.
         */

        public boolean action(Event e, Object arg)
        {
            if(e.target instanceof Button)
            {
                if(">>>" == arg)
                {
                    incrementCalendar();
                } else if("<<<" == arg)
                {
                    decrementCalendar();
                } else if (arg != "")
                {
                    Integer tempInt = Integer.valueOf((String)arg);
                    dayselected = tempInt.intValue();
                    dateSelected = getDateSelected();
                    displayBannerText(dateSelected);
                    repaint();
                 }
            }
            return false;
        }


        /**
         * Given a Date, set up the calendar elements to display the
         * appropriate dates on the appropriate calendar buttons.
         */

        private void setCalendar(Date dt)
        {
            //clear calendar
            for(int i = 0; i < 42; i++)
            {
                myButton[i].setLabel("");
            }

            int thisMo = dt.getMonth();
            int thisDy = dt.getDay();
            int thisYr = dt.getYear();

            //Find the day of the week of the first
            Date firstday = new Date(thisYr, thisMo, 1);
            int dayoffirst = firstday.getDay();
            buttonShift = dayoffirst;

            int dayspermonth = getDaysPerMonth(thisMo);
            for(int i = 1; i < dayspermonth+1; i++)
            {
                myButton[i+buttonShift-1].setLabel(Integer.toString(i));
            }
        }


        /**
         * Given a Date, set the text field to display it as a
         * string containing the month and the year.
         */

        private void setMonthString(Date dt)
        {
            thismonth = dt.getMonth();
            thisyear = dt.getYear();

            String monthstring;

            switch(thismonth)
            {
                case 0:
                    monthstring = "January";
                    break;
                case 1:
                    monthstring = "February";
                    break;
                case 2:
                    monthstring = "March";
                    break;
                case 3:
                    monthstring = "April";
                    break;
                case 4:
                    monthstring = "May";
                    break;
                case 5:
                    monthstring = "June";
                    break;
                case 6:
                    monthstring = "July";
                    break;
                case 7:
                    monthstring = "August";
                    break;
                case 8:
                    monthstring = "September";
                    break;
                case 9:
                    monthstring = "October";
                    break;
                case 10:
                    monthstring = "November";
                    break;
                case 11:
                    monthstring = "December";
                    break;
                 default:
                    monthstring = "Month";
                    break;
                }
            String temp = (monthstring +" ");
            temp = temp + (Integer.toString(1900 + thisyear));
            date.setText(temp);
        }


        /**
         * Increments the calendar (both Mo/Yr text field and date buttons)
         * to the next sequential month/year combination.
         */

        private void incrementCalendar()
        {
            thismonth += 1;
            if(thismonth > 12)
            {
                thismonth = 0;
                thisyear += 1;
            }
            Date incDate = new Date(thisyear, thismonth, 1);
            setMonthString(incDate);
            setCalendar(incDate);
        }

        /**
         * Decrements the calendar (both Mo/Yr text field and date buttons)
         * to the previous sequential month/year combination.
         */

        private void decrementCalendar()
        {
            thismonth -= 1;
            if(thismonth < 0)
            {
                thismonth = 11;
                thisyear -= 1;
            }
            Date decDate = new Date(thisyear, thismonth, 1);
            setMonthString(decDate);
            setCalendar(decDate);
        }

        /**
         * Given a month (represented as an integer), return the
         * number of days in that month (corrects for leap years).
         */

        private int getDaysPerMonth(int m)
        {
            switch(m)
            {
                case 0:
                    days = 31;
                    break;

                case 1:
                    //Correct for a leap year
                    int tempYear = 1900 + thisyear;
                    if((tempYear % 4) == 0)         // Could be leap
                    {
                        if((tempYear % 100) == 0 && // Centuries aren't
                           (tempYear % 400) != 0)   // Except every 4th
                            days = 28;
                        else
                            days = 29;
                        break;
                    }
                    days = 28;
                    break;

                case 2:
                    days = 31;
                    break;

                case 3:
                    days = 30;
                    break;
                case 4:
                    days = 31;
                    break;

                case 5:
                    days = 30;
                    break;

                case 6:
                    days = 31;
                    break;

                case 7:
                    days = 31;
                    break;

                case 8:
                    days = 30;
                    break;

                case 9:
                    days = 31;
                    break;

                case 10:
                    days = 30;
                    break;

                case 11:
                    days = 31;
                    break;

                default:
                    days = 31;
                    break;
             }
              return days;
        }

        /**
         * return the date that was selected by pushing a button
         * on the calendar
         */

        private Date getDateSelected()
        {
            dateSelected = new Date(thisyear, thismonth, dayselected);
            return dateSelected;
        }

        /**
         * Given a date, set the banner text message
         */

        private void displayBannerText(Date dt)
        {
            message = (String)eventHash.get(dt);

            if(message == null)
            {
                int tempMo = (dt.getMonth()) + 1;
                int tempYr = (dt.getYear());
                int tempDy = (dt.getDate());
                message = "You selected ";
                message += Integer.toString(tempMo);
                message += "/" + Integer.toString(tempDy);
                message += "/" + Integer.toString(tempYr);
            }
            CreateBannerParams();
         }

        /**
         * An initialization function designed to get parameter info,
         */

        private void getParamData()
        {
            String param = null;
            boolean datapresent = true;
            int i = 1;

            while(datapresent)
            {
                try
                {
                    param = getParameter("EVENT"+ Integer.toString(i));
                } catch(Exception e)
                {
                    System.out.println(e);
                }

                if(param == null)
                {
                    datapresent = false;
                } else
                {
                    i += 1;
                    parseHashData(param);
                }
            }
        }


        /**
         * A small utility to take the param info, turn it into program-friendly
         * classes and strings and then put all that info into a hash table.
         * The string fed to parseHashData is the raw param string from the HTML.
         */

        private void parseHashData(String str)
        {
            //Separate the param string into its date/event components
            int sep = str.indexOf(':');
            String evt = str.substring(sep+1);
            String evtdate = str.substring(0, sep);

            //make the evtdate into a date class format (YY/MM/DD). The input
            //string is in the U.S.-style MM/DD/YY format.

            int sel1 = evtdate.indexOf('/');
            int sel2 = evtdate.lastIndexOf('/');

            String mo = evtdate.substring(0, sel1);
            String dy = evtdate.substring(sel1+1, sel2);
            String yr = evtdate.substring(sel2+1);

            int intMo = Integer.parseInt(mo);
            int intDay = Integer.parseInt(dy);
            int intYr = Integer.parseInt(yr);

            Date newDate = new Date(intYr, intMo-1, intDay);

            // Put the evt and evtdate info into a Hashtable
            eventHash.put(newDate, evt);
        }

    /**
     * The main thread event function
     */

    public void run()
    {
        Thread me = Thread.currentThread();
        me.setPriority(Thread.MIN_PRIORITY);

        repaint();

          while(loadedtext)
            {
              drawText();
              nextPos();

              textCanvas.repaint();

              try
              {
                 Thread.sleep(150);
              }  catch(InterruptedException e)
              {}
            }
    }

    /**
     * Draws the appropriate text string onto the (invisible) textGC
     * graphics context. Used prior to a repaint request.
     */

    public synchronized void drawText()
    {
        if(loadedtext)
        {
           //following code for banner...
           textGC.setColor(Color.blue);
           textGC.fillRect(0, 0, 300, bannerHeight);
           textGC.setColor(Color.white);
           textGC.setFont(msgFont);
           textGC.drawString(message, msgX, msgY);
        }
    }

    /**
     * Scrolls the banner text one "position" to the left.
     */

    public synchronized void nextPos()
    {
         msgX -= 10;
         if((msgX + msgWidth) < 0)
         {
              msgX = lastS.width;
         }
         repaint();
    }


    /**
     * Create the original banner parameters (font size, etc.)
     */

    public void CreateBannerParams()
    {
        int w = 300;
        int h = 20;
        lastS.width = w;
        lastS.height = h;

        int refH = 14;
        Font tf = new Font("TimesRoman", Font.BOLD, refH);
        textGC.setFont(tf);
        FontMetrics tfm = textGC.getFontMetrics(tf);
        int fh = tfm.getHeight();
        fh = refH*(h-2)/fh;
        msgFont = new Font("TimesRoman", Font.BOLD, fh);
        FontMetrics fm = textGC.getFontMetrics(msgFont);
        fh = fm.getHeight();
        msgX = w;
        msgY = ((h-fh) >> 1) + fm.getAscent();
        msgWidth = fm.stringWidth(message);
    }
        //{{DECLARE_CONTROLS
    java.awt.Panel selPanel;
    java.awt.Button leftButton;
    java.awt.TextField date;
    java.awt.Button rightButton;
    //}}

}



/**
 * Subclasses Canvas object which allows display of running (banner) text
 */

class MyCanvas extends Canvas
{
    Image im;

    MyCanvas(Image img)
    {
        im = img;
    }

    public void paint(Graphics g)
    {
        g.drawImage(im, 0, 0, this);
    }

    public void update(Graphics g)
    {
        paint(g);
    }
}