How to add a function to dropdown list? - processing

Question

I've added a drop down list in processing using controlp5 library. I want to transmit data serially to Arduino when certain item is selected in the list. How to add the control for this purpose?
Here's my code:
void setup{
d1 = cp5.addDropdownList("color")
.setPosition(((width/4)-50), ((height/2)-40))
.setBackgroundColor(color(37, 126, 214))
.setFont(font1)
.setItemHeight(25)
.setBarHeight(20)
.addItem("red ", d1)
.addItem("blue ", d1)
.addItem("green ", d1)
}
I want to send a character 'r','b','g' to Arduino when each item is selected respectively. Suggest me how to write the code for my purpose.

Answer 1

Dropdown list is deprecated as the author says in the example, I think the simplest way is to implement ScrollableList, which is more flexible, and send the data though Serial Port to Arduino.
// Import java utils, for the list to add to the scrollable list
import java.util.*;
// Import ControlP5 library and declare it
import controlP5.*;
ControlP5 cp5;
// Import the Serial port and declare it
import processing.serial.*;
Serial myPort; // Create object from Serial class
void setup() {
size(400, 400);
// Initialize the Serial port
String portName = Serial.list()[0];
myPort = new Serial(this, portName, 9600);-
// Initialize the dropdown list
cp5 = new ControlP5(this);
List l = Arrays.asList("red", "green", "blue");
/* add a ScrollableList, by default it behaves like a DropdownList */
cp5.addScrollableList("dropdown")
.setPosition(100, 100)
.setSize(200, 100)
.setBarHeight(20)
.setItemHeight(20)
.addItems(l)
;
}
void draw() {
background(255);
}
// Dropdown callback function fromthe ScrollableList, triggered when you select an item
void dropdown(int n) {
/* request the selected item based on index n and store in a char */
String string = cp5.get(ScrollableList.class, "dropdown").getItem(n).get("name").toString();
char c = string.charAt(0);
// Write the char to the serial port
myPort.write(c);
}
On the Arduino side
char val; // Data received from the serial port
void setup() {
Serial.begin(9600); // Start serial communication at 9600 bps
}
void loop() {
while (Serial.available()) { // If data is available to read,
val = Serial.read(); // read it and store it in val
}
}