Error: The constructor xxx is undefined

Eduardo__

Error: The constructor xxx is undefined

in Contributed Library Questions • 1 year ago

Hi there.

I´m a newbie in processing. I´m trying to make a class for driving many gifs animation. For animiation I use the "Gif" library. I download this library in processing website. It´s intended for animate gif files. But I need to display each frame of animation. Because of that, I´m creaing this class.

When I try to compile and run the project, I give the folowing error:

"The constructor Gif(Stiling.anim, String) in undefined" (this error respects to yelow line at code. see below)

class anim { //Plays gif animation
import gifAnimation.*;
float px,py,len,frame=0;
Gif nonLoopingGif;

// void load_gif(float x, float y) {
void anim(float x, float y) {
px=x;
py=y;

nonLoopingGif = new Gif(this, "ink splash2.gif");
len=nonLoopingGif.length;

nonLoopingGif.play();
nonLoopingGif.ignoreRepeat();
}

void play_gif() { //create anitated image and animate it. Then, it destroys itself from memory

if (frame<len) {
image(nonLoopingGif, px, py);
frame++;
}
}

I don´t know why this error is occuring. WHy cannot the compiller find the Gif constructor? I included the gifAnimation library into class.

thanks for any help. :)

Replies(21)

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

Check the Technical FAQ... Why I can't create a class of a library from my own classes?

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

I tried like that example, but now I gave the error: "The function gifapp(Stiling.anim, String) does not exist."

Please, see my code:

class anim { //Plays gif animation
// import gifAnimation.*;
float px,py,len,frame=0;
private Gif nonLoopingGif;

// void load_gif(float x, float y) {
public anim(Gif gifapp, float x, float y) {
px=x;
py=y;

nonLoopingGif = gifapp(this, "ink splash2.gif");
//nonLoopingGif = new Gif(this, "ink splash2.gif");
len=nonLoopingGif.length;

nonLoopingGif.play();
nonLoopingGif.ignoreRepeat();
}

void play_gif() { //create anitated image and animate it. Then, it destroys itself from memory

if (frame<len) {
image(nonLoopingGif, px, py);
frame++;
}
}

}

Please, I cannot understand.

Ale_

Re: Re: Error: The constructor xxx is undefined

1 year ago

Hola Eduardo!
El problema que tienes es que cuando le pasas el parámetro "this" al Gif, éste lo que se espera es que le pases el PApplet donde estás trabajando, pero como estás trabajando dentro de una clase ese "this" acaba refiriéndose a la instancia de la clase Anim en la que estás generando el Gif. ¿Me entiendes?
Lo que tienes que hacer es pasarle al constructor el PApplet actual, de manera que, al instanciar el Gif se lo puedas pasar.

      public anim (PApplet myApplet, Gif gifapp, float x, float y){
        px=x;
        py=y;
        nonLoopingGif = gifapp(myApplet, "ink splash2.gif");
        ...más código aquí...
       }

   Y cuando hagas la instancia le añades el "this" a la misma:
   myAnim=new Anim(this,nombre_del_gif,valor_de_x,valor_de_y)

Esto debería funcionarte, ya comentas.
Saludos · Ale

Pd.: I thought, looking at your name, you´re a spanish-speaker. If you prefer english, just tell me.

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

thank you very much Mr 60rpm.tv,.. it worked! Thanks for Mr. phi.lho, too.

But I had to use the "new" statement inside class:

class anim { //Plays gif animation
// import gifAnimation.*;
float px,py,len,frame=0;
private Gif nonLoopingGif;

anim (PApplet myApplet, float x, float y){
px=x;
py=y;
nonLoopingGif = new Gif(myApplet, "ink splash2.gif");
//len=nonLoopingGif.length;
len=120;

...more code and functions...
}

Thanks again.

Eduardo

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

I tried to be more explicit in the article, let me know if it is clearer now. Thanks.

Ale_

Re: Error: The constructor xxx is undefined

1 year ago

Mmm... I see... issues of fast answering... ;-)
I´m glad it worked... :-)
· Ale

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

Do you know whether is possible to destruct(release memory) some object created with the command "new"?

Ale_

Re: Re: Error: The constructor xxx is undefined

1 year ago

This is Java for better for worse... :-)
Look here, page 119:
>> highscore.googlecode.com/files/Thinking%20In%20Java%204th.pdf
· Ale

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

Thanks again. I must take care to not create too much objects.

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

To answer in a more direct way, a created object lives as long as it is referenced by something referenced in the main application. So, if you create, for example, a bunch of objects and put them in a global array, they will remain live unless you assign null (or another object) to the slot where they are referenced. Then the garbage collector will take care of them, sooner or later.

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

Let me see if I understood:

If I create an object(or an array of them), I can release ir for garbage collector if I set a null pointer to this created object?

And in case of an array of objects, can I release(to garb. collec.) each item of this array separately(setting null pointer to them)?

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

Yes to the second question. I am not sure to understand the last part of the first question. But if you have a variable holding (a reference to) an array, full of objects, and nothing else references these objects (a same object can be reference by several collections and variables), if you assign null to this variable, the whole array and its objects will be collected.

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

yes, but can I make the same(a null pointer to just one or several items) whether I want to release just one(or several) item of this arrays of objects?

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

Again, yes.

rbrauer

Re: Error: The constructor xxx is undefined

1 year ago

Getting back to the original subject, it can be annoying if you have a situation like this where you need a reference to the PApplet, you're writing classes in a pde, using MyThing(PApplet myPapplet, ...){} and constructing the instance by passing the name of the sketch. Now if you save a new version of the sketch (I often save many versions), you have to go in and change all the new MyThing(mySketch, ...) to new MyThing(myNewSketch, ...). I recently discovered that you can do getComponentAt(0,0) to dynamically get the PApplet instance. I think it works from any pde code. It is a method inherited from some part of Swing, the Java GUI stuff that Processing uses.

By the way, I don't really understand why you can put the sketch name in a constructor that is looking for a PApplet. Wouldn't the sketch name be a Class and not an instance?

Eduardo__

Re: Error: The constructor xxx is undefined

1 year ago

Very good Mr. rbauer. But I not understood completely.

Can you give us an example?

Thanks a lot! :)

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

rbrauer, I don't get your remarks on sketch name. You don't call new Thing(mySketch, ....), you call new Thing(this, ...)

rbrauer

Re: Error: The constructor xxx is undefined

1 year ago

void setup() {
}

void draw() {
}

class Blah {
  
  Blah(PApplet in) {
  }
  
}

class Other {
  
  Blah otherBlah;
  
  Other() {

    //otherBlah = new Blah(this);
    /*
    above line doesn't work - Blah constructor needs
    a PApplet not an "Other" (the instance we are in here)
    */
    
    //otherBlah = new Blah(sketch_feb04a.this);
    /*
    you can use (className [dot] this) to get the 
    enclosing instance, I was confused because I 
    forgot about the "this" part in my previous post
    the Java here looks like this -
    
    class sketch_feb04a extends PApplet {
      ...
      class Other {
        ...
        from here sketch_feb04a.this refers to the
        enclosing sketch_feb04a instance
      }
    }
    
    this works but if I re-saved I would have to change
    sketch_feb04a.this to newSketchName.this
   */
   
   otherBlah = new Blah((PApplet)getComponentAt(0,0));
   /*
   the above line will work no matter the filename
   (the name of your sketch class)
   I forgot to mention before
   you have to cast it to PApplet
   */
    
  }
  
}

In the original example Eduardo gave the line that didn't work, new Gif(myApplet, "ink splash2.gif") could be changed to new Gif((PApplet)getComponentAt(0,0), "ink splash2.gif") as long as his anim class was defined in a pde and not a java file.

Eduardo__

Re: Re: Error: The constructor xxx is undefined

1 year ago

But Mr. rbrauer, the line new Gif(myApplet, "ink splash2.gif") worked well.

Thanks a lot!

PhiLho

Re: Error: The constructor xxx is undefined

1 year ago

As long as each constructor pass around the PApplet parameter, it has access to it.

Thinking about it, there is an even simpler way to share this value among classes, as long as they are defined a .pde file. Ie. my trick won't work for a library.
Define a global PApplet field:
PApplet sketch = this; // 'sketch' can be named anything you want (almost)

Nested classes (all classes in .pde files, eg. in the main tab) have direct access to it, thus can do:
foo = new LibraryClass(sketch, other, param);

Simple, less parameters to constructors, nice.

Ale_

Re: Error: The constructor xxx is undefined

1 year ago

Hi phi.lho, that´s a good workaround of processingjs, because this one doesn´t know what 'g' is... so if you need to 'translate' to processingjs a processing sketch that uses 'g' as parameter you have to declare it explicitly at the beginning:

"PApplet g= this;"

Ale · http://60rpm.tv/i

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