isPrototypeOf in indesign

Question

Hi am relativly new to indesign scripting and would like to figure out if an object is a subtype of a class. Example: I want to iterate over all page items and take everything that is not a graphic:

layer = app.activeDocument.layers[layerIndex];

for (i = 0; i < layer.allPageItems.length; i++) {
  alert(layer.allPageItems[i].reflect.name)
  if(layer.allPageItems[i].isPrototypeOf (Graphic) ) {
    alert("Graphic");
  } else {
    ....
  }
}

howver the if nver matches. Are there any examples of how to use isPrototypeOf? What do I have to do to test if an object is of a certain type or a subclass of it?

edit: To clarify, I am trying to test if I have an Instance of anything that inherited from Graphic.

But as far as I can see now that seems to be impossible.

score 2 · Answer 1 · answered Jun 04 '12 at 15:32

2

You probably want the instanceof operator.

if (layer.allPageItems[i] instanceof Graphic) {
    alert("Graphic");
} else {
    ....
}

You could also use isPrototypeOf but you have to reverse the order and get the prototype itself, not the constructor. So it would look like this:

if (Graphic.prototype.isPrototypeOf(layer.allPageItems[i])) {
    alert("Graphic");
} else {
    ....
}

answered Jun 04 '12 at 15:32

Matthew Crumley

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Both methods wont work for suptypes of Graphic, like e.g. Image. I have to test for Image directly. – ted Jun 13 '12 at 22:41

score 2 · Answer 2 · edited Jun 06 '12 at 19:39

2

You can get access to the essence of the pageItem by calling the getElements() method. It returns an array of the original material. Given a rectangle on a page (nothing else) :

app.activeDocument.allPageItems[0].getElements()[0] instanceof Rectangle //true;

edited Jun 06 '12 at 19:39

Matthias

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answered Jun 05 '12 at 19:28

Loic Aigon

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score 1 · Answer 3 · answered Jun 04 '12 at 15:19

1

Are you sure its not supposed to be

Graphic.isPrototypeOf(layer.allPageItems[i])

or something like

Graphic.prototype.isPrototypeOf(layer.allPageItems[i])

?

Your current version sounds like its backwards.

answered Jun 04 '12 at 15:19

hugomg

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i have no clue how to use it thats why I am asking – ted Jun 05 '12 at 15:36
If you have no idea how to use it how do you even know it exists? – hugomg Jun 05 '12 at 17:27
you know adobe delviers a documentation, unfortunately it lacks examples (I know there come a few with indesign,...) – ted Jun 06 '12 at 05:55
The later version is correct, however it won't tell me true if the item tested is a subtype of graphic. – ted Jun 13 '12 at 22:43

ted · Answer 4 · 2012-06-16T10:24:25.370

Apparently this is not possible, I also asked on the adobe Forums with this result: http://forums.adobe.com/message/4461211#4461211

So the short answer is, I have no way to check if I hold an object wich is an instace of someClass or a child thereof. Neither reflection nor isPrototypeOf help.

I might try casting in a try catch block but consider this as ugly. Thus I will go with the solution suggested on the adobe Forums, test for all possible heirs (children/classes inherting from base) and the base class. This is ugly and lengthy but I have not found a better solution.

edit: here is an exceprt from one of adobes examples, it allows for the switch syntax avoidng an endless if construct:

switch (app.selection[myCounter].constructor.name){
    case "Rectangle":
    case "Oval":
    case "Polygon":
    case "GraphicLine":
    case "TextFrame":
        myObjectList.push(app.selection[myCounter]);
        break;
}

isPrototypeOf in indesign

4 Answers4