Functions and Arrays
Digital Clocks, HTML Page Parameters - Con't
In the following applet code we introduce parameters, which pass values to your applet from the embedding HTML page. So you can change to behavior, colors etc. of your applet before it is started to custimize it at the user's will. In this applet we make the background color and the foreground color customizable (pass the colors as hexadecimal values, like in HTML code). Additionally you can change the font size (so you can adjust the font to the size of the applet) and whether you prefer 12 hour (U.S.) format or military (European) format. The four applets you can see here use all the same class file, but different parameters. See the sourcecode of this HTML page, to see the details of how this is done.
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//Sourcecode
import java.awt.*;
import java.applet.*;
//we need to import the util package for the time functions
import java.util.*;
public class Project19 extends Applet implements Runnable
{
Thread runner;
Image Buffer;
Graphics gBuffer;
Color bgColor, fgColor;
int fontSize;
int format24;
public void init()
{
//create off-screen image we can draw to
Buffer=createImage(size().width,size().height);
gBuffer=Buffer.getGraphics();
//Interprete the parameters from the HTML page
//read the fontSize parameter
String clockSizeStr=getParameter("font_size");
//we have to convert the String to an integer, base is 10 (decimal)
fontSize=Integer.parseInt(clockSizeStr, 10);
format24=Integer.parseInt(getParameter("format24"), 10);
String redStr, greenStr, blueStr;
int redInt, greenInt, blueInt;
//read the background color parameter
String bgColorStr=getParameter("bg_color");
redStr=bgColorStr.substring(0,2);
greenStr=bgColorStr.substring(2,4);
blueStr=bgColorStr.substring(4);
//during conversion, we convert from hexadecimal (base 16)!
redInt=Integer.parseInt(redStr, 16);
greenInt=Integer.parseInt(greenStr, 16);
blueInt=Integer.parseInt(blueStr, 16);
bgColor=(new Color(redInt, greenInt, blueInt));
//read the foreground color parameter
String fgColorStr=getParameter("fg_color");
redStr=fgColorStr.substring(0,2);
greenStr=fgColorStr.substring(2,4);
blueStr=fgColorStr.substring(4);
redInt=Integer.parseInt(redStr, 16);
greenInt=Integer.parseInt(greenStr, 16);
blueInt=Integer.parseInt(blueStr, 16);
fgColor=(new Color(redInt, greenInt, blueInt));
}
public void start()
{
if (runner == null)
{
runner = new Thread (this);
runner.start();
}
}
public void stop()
{
if (runner != null)
{
runner.stop();
runner = null;
}
}
public void run()
{
while(true)
{
//halt the thread for 100 ms here
try {runner.sleep(100);}
catch (Exception e) { }
repaint();
}
}
public void update(Graphics g)
{
paint(g);
}
public void paint (Graphics g)
{
//create a new time object
Date today=new Date();
//get the seconds, minutes and hours
int sec=today.getSeconds();
int min=today.getMinutes();
int hour=today.getHours();
String secStr, minStr, hourStr;
//copy the time integers to our string objects
//if values are less than 10 we add a 0
//12 hour US time format with AM and PM
boolean am;
if(hour<12)
am=true;
else
am=false;
if(format24==0&&hour>12)
hour-=12;
if(hour<10)
hourStr="0"+hour;
else
hourStr=""+hour;
if(min<10)
minStr="0"+min;
else
minStr=""+min;
if(sec<10)
secStr="0"+sec;
else
secStr=""+sec;
//repaint the background in the background color
gBuffer.setColor(bgColor);
gBuffer.fillRect(0,0,size().width,size().height);
//draw a thin frame in the foreground color
gBuffer.setColor(fgColor);
gBuffer.drawRect(0,0,size().width-1,size().height-1);
String outputString=hourStr+":"+minStr+":"+secStr;
if(format24==0)
{
if(am==true)
outputString+=" AM";
else
outputString+=" PM";
}
Font clockFont=new Font("Helvetica", Font.BOLD, fontSize);
//measure the size of the string to center it
FontMetrics fm = gBuffer.getFontMetrics(clockFont);
int stringWidth=fm.stringWidth(outputString);
int stringHeight=gBuffer.getFontMetrics().getAscent()-fontSize/4;
//set the font and the foreground color
gBuffer.setFont(clockFont);
gBuffer.setColor(fgColor);
//center the string inside the applet
gBuffer.drawString(outputString,
(size().width-stringWidth)/2, (size().height+stringHeight)/2);
//copy the buffer to the screen (no flicker!)
g.drawImage (Buffer,0,0, this);
}
}
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