Thanks in advance for your help! I'm getting 'The constructor sketch_feb09b.CountupTimer() is undefined' for this code. I've tried putting the object declaration in the setup() block with the same result. I'm sure it's something stupid. Thanks again!

   PFont fontA;
   CountupTimer CountupTimer1 = new CountupTimer();
   
void setup()
 {
   size(1280, 720);
   
   fontA = loadFont("HelveticaNeue-Bold-48.vlw");
   textFont(fontA, 32); // Set the font and its size (in units of pixels)
   background(0);
 }
 
void draw()
{
  //DISPLAY TIMER
   textAlign(CENTER);
   text(CountupTimer1.display(), width/2, height-10);
}

class CountupTimer {
 int milliseconds;
 int seconds;
 int minutes;
 int hours;
 str displayTime;

 // Arguments: Timer Start in Millis; show minutes True/False; show hours true/false (if minutes is false, hours defaults to false)
 CountupTimer(int timerStart, boolean showMinutes, boolean showHours) {
   timerStart = millis();
   showMinutes = true;
   showHours = false;
 }

 void display() {
   // calculate elapsed time in days, hours, minutes, seconds, and milliseconds
   milliseconds = millis() - timerStart;
   seconds = milliseconds / 1000;
   minutes = seconds / 60;
   hours = minutes / 60;
   days = hours / 24;
   
   // Now we need to subtract elapsed minutes from seconds, hours from minutes, etc,
   // so that we don't end up with silly things like "01:65:3912:39123421"
   milliseconds -= seconds * 1000;
   seconds -= minutes * 60;
   minutes -= hours * 60;
   hours -= days * 24;
   
   // Lets set up our string before we actually print it:
   if(showMinutes && showHours) displayTime = nf(hours,2,0)+":"+nf(minutes,2,0)+":";
   else if(showMinutes) displayTime = nf(minutes,2,0)+":";
   displayTime += nf(seconds,2,0)+":"+nf(milliseconds,3,0);
   
   return displayTime;
 }
}

Ahhh, much better. Thanks a ton!

Corrected code:

PFont fontA;
  CountupTimer CountupTimer1 = new CountupTimer(millis(),true,false);
 
void setup()
{
  size(1280, 720);
 
  fontA = loadFont("HelveticaNeue-Bold-48.vlw");
  textFont(fontA, 32); // Set the font and its size (in units of pixels)
}

void draw()
{
  background(0);
 //DISPLAY TIMER
  textAlign(CENTER);
  text(CountupTimer1.display(), width/2, height-10);
}

class CountupTimer {
int milliseconds;
int seconds;
int minutes;
int hours;
int days;
String displayTime;
boolean showMinutes;
boolean showHours;
int timerStart;

// Arguments: Timer Start in Millis; show minutes True/False; show hours true/false
CountupTimer(int tempStart, boolean tempMinutes, boolean tempHours) {
 timerStart = tempStart;
 showMinutes = tempMinutes;
 showHours = tempHours;
}

String display() {
  // calculate elapsed time in days, hours, minutes, seconds, and milliseconds
  milliseconds = millis() - timerStart;
  seconds = milliseconds / 1000;
  minutes = seconds / 60;
  hours = minutes / 60;
  days = hours / 24;
 
  // Now we need to subtract elapsed minutes from seconds, hours from minutes, etc,
  // so that we don't end up with silly things like "01:65:3912:39123421"
  milliseconds -= seconds * 1000;
  seconds -= minutes * 60;
  minutes -= hours * 60;
  hours -= days * 24;
 
  // Lets set up our string before we actually print it:
  if(showMinutes && showHours) displayTime = nf(hours,2,0)+":"+nf(minutes,2,0)+":";
  else if(showMinutes) displayTime = nf(minutes,2,0)+":";
  displayTime += nf(seconds,2,0)+":"+nf(milliseconds,3,0);
 
  return displayTime;
}
}