Learning Processing: A Beginner's Guide to Programming Images ...

Create and make an asynchronous request
htmlRequest = new HTMLRequest(this, " http://www.yahoo.com " );
htmlRequest.makeRequest();
timer.start();
background(0);
}
void draw() {
background(back);
// Every 5 seconds, make a new request
if (timer.isFinished()) {
htmlRequest.makeRequest();
println( "Making request! ");
timer.start();
}
// Draw some lines with colors based on characters from data retrieved
for (int i = 0; i < width; i + + ) {
if (i < html.length()) {
int c = html.charAt(i);
stroke(c,150);
line(i,0,i,height);
}
}
// Animate rectangle and dim rectangle
fill(255);
noStroke();
rect(counter,0,10,height);
counter = (counter + 1) % width;
back = constrain(back – 1,0,255);
}
// When a request is finished
void netEvent(HTMLRequest ml) {
html = ml.readRawSource(); // Read the raw data
back = 255; // Reset background
println( "Request completed! "); // Print message
}
// Timer Class from Chapter 10
class Timer {
int savedTime;
boolean running = false;
int totalTime;
Timer(int tempTotalTime) {
totalTime = tempTotalTime;
}
void start() {
running = true;
savedTime = millis();
}
boolean isFinished() {
int passedTime = millis() – savedTime;
if (running & & passedTime > totalTime) {
running = false;
An HTML Request object to request
the source from a URL.
fi g. 18.11
Data Input 343
A request is made every 5 s. The data is not
received here, however, this is only the request.
The data is received in the netEvent() function
which is automatically called whenever data
is ready.