Processing in Eclipse with Multiple Classes using Singleton for Processing function access?

tmaccallum

Processing in Eclipse with Multiple Classes using Singleton for Processing function access?

in Integration and Hardware • 3 years ago

I'm running through the Processing in Eclipse tutorial ( http://processing.org/learning/eclipse/) and I'm curious about the situation where one is running multiple classes. The tutorial suggests passing a reference to the PApplet when creating every other class where one would need to use a Processing function. It strikes me though that it would be easier to use a singleton style access. In this case one would just type MyApp.Instance.(whatever) when needing to call a Processing function. Is there some way that the PApplet can provide a public static reference to itself so that other classes in the code can use that to call all the Processing functions?

I tried creating it myself but my other classes wouldn't recognize the MyApp.Instance. I'm very new to Java so I really have no idea what I'm doing. I'm actually not really sure how the Processing "main" function works and whether it's sensible to have a public reference to it.

Here's the main sketch used in the eclipse tutorial:

               
                import processing.core.*;
                

                public class MyProcessingSketch extends PApplet {
                

                 public void setup() {
                 size(200,200);
                 background(0);
                 }
                

                 public void draw() {
                 stroke(255);
                 if (mousePressed) {
                 line(mouseX,mouseY,pmouseX,pmouseY);
                 }
                 }
                

                 public static void main(String args[]) {
                 PApplet.main(new String[] { "--present", "MyProcessingSketch" });
                 }

What I attempted was to add a:

private static MyProcessingSketch mInstance = null
public MyProcessingSketch Instance()
{
if (null == mInstance)
{
mInstance = new MyProcessingSketch();
}
return mInstance;
}

I don't know why this doesn't work, but I don't really know how the main function works or what processing/java is doing behind the scenes here.

Thanks,

Tavis

Replies(1)

PhiLho

Re: Processing in Eclipse with Multiple Classes using Singleton for Processing function access?

3 years ago

You can make a class with a single static field: set the field when you create your PApplet, and access it when you need the instance.

public class PAppletAccess
{
private static PApplet mInstance = null;
public static void SetInstance(PApplet instance)
{
mInstance = instance;
}
public static PApplet GetInstance()
{
return mInstance;
}
}

Or just add this field and the getter to your class extending PApplet...

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