Processing/ Rhythm record - processing

Question

I'm doing a student project. I'm trying to record a rhythmic composition and draw a grid of vertical lines, based on it. It's going to look like knocking a tram-pam-pam over a wooden box (arduino; standard firmata). Then processing needs to map the time of this record and the width of the screen - and draw vertical lines in the places of the knocks.
Please, help, where to look to record this time and then map it to the screen.
So far I have this code. But it only draws lines on the knocks when there is a screen space; and saves in pdf.
import processing.serial.*;
import cc.arduino.*;
import processing.pdf.*;
Arduino arduino;
Serial myPort;
int x = 0;
void setup() {
size(500, 500);
background(#ffffff);
println(Arduino.list());
arduino = new Arduino(this, "/dev/tty.usbmodem1411", 57600);
//Set the Arduino digital pins as inputs.
arduino.pinMode(0, Arduino.INPUT);
beginRecord(PDF, "everything.pdf");
}
void draw() {
stroke(0);
for (int i = 0; i <= 0; i++) {
if (arduino.analogRead(i)>0) {
line(x, 0, x, height);
}
else {
x +=1;
}
}
}
void keyPressed() {
endRecord();
codexit();
}

Answer 1

I got this done, finally. Suppose, that it can be done better and wider, but the fact is that it works.
The small video about the outcome:
https://www.dropbox.com/s/1dp5tqqx16zp4l7/Abramova-5FCC0022-video.mov?dl=0
And the code:
import processing.serial.*;
import cc.arduino.*;
Arduino arduino;
PrintWriter output;
// The serial port:
Serial myPort;
int t = millis();
int[] time;
void setup() {
size(500, 500);
background(#ffffff);
// Prints out the available serial ports.
println(Arduino.list());
// Modify this line, by changing the "0" to the index of the serial
// port corresponding to your Arduino board (as it appears in the list
// printed by the line above).
arduino = new Arduino(this, "/dev/tty.usbmodem1411", 57600);
// Alternatively, use the name of the serial port corresponding to your
// Arduino (in double-quotes), as in the following line.
//arduino = new Arduino(this, "/dev/tty.usbmodem621", 57600);
// Set the Arduino digital pins as inputs.
arduino.pinMode(0, Arduino.INPUT);
// Creates the output for the time, dedicated to the beats.
output = createWriter("time.txt");
}
void draw() {
// when arduino sends signal, store the current
// time in milliseconds since the program started
if (arduino.analogRead(0)>30) {
// grabs the time, passed before the beat from start
String numbers = "millis()";
delay(100);
output.print (millis() + ",");
}
}
void keyPressed() {
output.flush(); // Writes the remaining data to the file
output.close(); // Finishes the file
}
void keyReleased() {
// Interprets the string from the saved beat sequence
String[] numbers = loadStrings("time.txt");
time = int(split(numbers[0],','));
stroke(0);
strokeWeight(5);
// Draws lines, based on a string
for (int i = 1; i < time.length; i++) {
int c = time[i]-time[0];
int d = time[time.length - 2];
int e = time[0];
int f = d-e;
// Vertical lines
line(c*500/f, 0 , c*500/f , height);
// Horisontal lines
line(0, c*500/f, width, c*500/f);
// Drawing rects
// Yellow
fill (255, 255, 0);
int m = (time [1] - time [0])*500/f;
int n = (time [2] - time [0])*500/f;
rect (m, m, n-m, n-m);
// Blue
fill (0, 0, 255);
int o = (time [8] - time [0])*500/f;
int p = (time [4] - time [0])*500/f;
rect (o, m, p-o, p-o);
// Red
fill(255, 0, 0);
int v = (time [3] - time [0])*500/f;
int k = (time [6] - time [0])*500/f;
int z = (time [8] - time [0])*500/f;
rect(v, p, z-v, k-v);
}
}