Printing: Can�t use draw drawString(...) in a loop!?

[Dirk Mohr]

Hello!
I�m writting a class to print simple Text. But in the print-Methode of the Interface Printable I can�t use a loop to put my Text on my page.
I have no idea why this code doesn�t work:

  
import java.awt.*;
import java.awt.print.*;
/** Die Klasse Printing stellt die Methode print(String[] str, int fontSize)
zur Verf�gung, die einen einfachen Text auf einem Drucker ausgibt */
public class Printing implements Printable 
{
private static PrinterJob pjob;
private static int page;
private static Printing p = new Printing();

private static String text[];
private static int f;

private static int x,y;
private static int dy;
private static int h;

private static int zeile;

public static void main(String args[])
{
//Zeilen des Texts, null steht f�r Leerzeile
String s[] = {"Hallo!", null, "Dies ist ein Test", "Noch `ne Zeile!" };
print(s, 11);
System.exit(0);
}

/* Initializierung des Drucks und Aufruf der eigentlichen Druckfunktion */
public static void print(String str[], int fontSize)
{
text = str;
zeile = 0;
f = fontSize; 
dy = f + f/2;

pjob = PrinterJob.getPrinterJob();
pjob.setPrintable( p, pjob.defaultPage());
x = (int) pjob.defaultPage().getImageableX() + 1;
y = (int) pjob.defaultPage().getImageableY() + 1;
h = (int) pjob.defaultPage().getImageableHeight(); 

if(pjob.printDialog())
{
try
{
pjob.print();
}
catch(PrinterException e)
{
System.err.println(e.toString());
}
}
}

/** Ausdruck des Textes */
public int print(Graphics pg, PageFormat pformat, int pageIndex) 
{
pg.setFont(new Font("Monospaced", Font.PLAIN, f));

if (pageIndex >= 0 && pageIndex <= countPages()) 
{
//THIS WORKS!
y=100;
pg.drawString(text[0], x, y);
y += dy;
pg.drawString(text[2], x, y);
y += dy;
pg.drawString(text[3], x, y);

//THIS DOES NOT WORK!
y=300;  
while(zeile<text.length)
{
if(text[zeile]!=null) pg.drawString(text[zeile], x, y);
y += dy;
zeile++; 
}
return Printable.PAGE_EXISTS;
   } 
   else 
   {
     return Printable.NO_SUCH_PAGE;
   }
}

/** Ermittelt die Anzahl der zu druckenden Seiten gem�� der
gegbenen Parameter */
public static int countPages()
{
int count = 0;
int help = y;
for(int j=0; j<text.length; j++)
{
help += dy;
if(help > y + h)
{
count++;
help = 0;
j--;
}
}
return count;
}
}

In advance, thanks a lot!
Regards, Dirk
[ April 17, 2002: Message edited by: Dirk Mohr ]

[Rob Ross]

When you say it doesn't work, can you please give a little more detail about what is actually happening?

[Dirk Schreckmann]

Bruder,
Considering:

//THIS DOES NOT WORK!
 
y = 300;
 
while (zeile < text.length) {
  
  if (text[zeile]!= null) {
    
    pg.drawString(text[zeile], x, y);
    
  }
  
  y += dy;
  
  zeile++;
  
}

It would seem to me that the first question to resolve is: Is the while loop ever entered - does (zeile < text.length) ever test true? Are you certain that the while loop is indeed entered?
Second: Does (text[zeile]!= null) ever test true for any of the components in text?
Otherwise, I don't see anything about your for-loop structure that could be behaving other than as expected.
Viel Glueck.

[Dirk Schreckmann]

I'm possibly not exploring anything less than obvious, but a quick and easy test to answer the above two questions could include something such as:

//THIS DOES NOT WORK!
 
y = 300;
 
while (zeile < text.length) {
  
  System.out.println("while loop entered...");
  
  if (text[zeile]!= null) {
    
    System.out.println("...inside if statement block");
    
    pg.drawString(text[zeile], x, y);
    
  }
  
  y += dy;
  
  zeile++;
  
}

Good Luck.

[Dirk Mohr]

Hello, to be more detailed:
The loop is not the problem, pg.drawString(text[zeile], x, y) is executed for every element of text[] that is not null. If I use

 
if(text[zeile]!=null) 
{
     pg.drawString(text[zeile], x, y);
     System.out.println(text[zeile]+" x:"+x+" y:"+y);
}

I get right that text on my screen I�d like to see on the printed page (plus the coordinates). That is:

Hallo! x:71 y:300
Dies ist ein Test x:71 y:332
Noch `ne Zeile! x:71 y:348

But on the printed page I only see the text that is generated by the (first) sequence of drawString(...) commands. This is realy mysterious, isn�t it?
Hope you can help me!
Regards, Dirk
[ April 18, 2002: Message edited by: Dirk Mohr ]

[Rob Ross]

OH, one important fact just popped up in my brain....the
print(Graphics pg, PageFormat pformat, int pageIndex)
method in the Printable interface actually gets called multiple times for the exact same page. It's important that your internal state be exactly consistent between invokation.
What is probably happening is that your print() method works correctly the first time it's called, and correctly runs your loop. But after this point, the ziele variable gets incremented passed the length of the text array, so the second time it's called, the while loop is not exectuted.
This seems to require a design change of your algorithm, because basically, this print() method is NOT reentrant.

[Dirk Mohr]

Year!
Rob, you hit the spot!
Thanks a lot, Dirk