Memory reuse with `fx/ext-instance-factory` about cljfx HOT 5 CLOSED

Hey!

JavaFX disallows reusing the same Node instance in a scene graph multiple times. Because of this, you cannot use fx/ext-instance-factory to return the same node multiple times, instead, you should create a fresh node every time, e.g.:

(defn
  svg
  "The actual workmap svg (as a JFX component"
  [{:keys [fx/context
           svg-string]}]
  {:fx/type fx/ext-instance-factory
   :create  (fn []
              (batik-load svg-string))})

from cljfx.

Alright, I'm going to use your implementation for now b/c it serviceable and keeping the code simpler. :) Thank you for your help. I'll shave this yak later and put up a more complete solution here

Your fix does make my larger app non longer resizeable (b/c the redraw is way too slow). I should extend the demo app later to show what I mean. Basically the FranzXaver SVG Nodes can be resized, so if you keep a Node in a subscription context you can reuse the Node and just rescale when your state/window-size changes.

I'll just need to poke around and see how to clone the Nodes in the right place. I still don't really understand why the Node isn't being copied automatically at the moment haha :))

Sorry my demo app is just spread over a bunch of files and not very minimal

from cljfx.

I think I see what you're saying

batik-load is a slow call and I originally didn't want to reparse the SVG string and regenerate the Node each time. As I understood, with your design the svg Node will get regenerated with batik-load only when the :svg-string key has changed.. right? It seems to accomplish the same result as long as you don't try to redraw the Node many times. I think it'd be suboptimal if you were say reusing a SVG Icon all over an application (and therefore calling batik-load a bunch).

My original plan was to load the Node once and to then store it in a subscription context. And then I'd reuse the Node directly when I want to draw it some place - but I was unclear on how to force the Node's duplication. Ideally I'd also look to dynamically resize the Node when the window size changes (not something I'm doing in this example though!). Here it'd have to reload and redraw it

I guess my big picture question was, shouldn't the Node have gotten automatically copied/duplicated when you do the svg function call since things are pass-by-value?

I'm a bit hazy on the details.. maybe doing things my way while also ensuring you are not redrawing the Node when the state/subscription is static is more difficult.

That all said, I do like that with your solution you don't need to save opaque objects in the context.. that does feel more Clojure-y

from cljfx.

Yeah as I understand it won't be re-created unless the SVG string changes. I don't see any way around it because this is how FranzXaver's SvgLoader class works — it only creates nodes from the input stream or file, and the nodes cannot be reused in multiple places. It would be nice if parsing and creating Nodes could be separated into independent steps, but judging by the source code it's not possible.

from cljfx.

Good luck :)

from cljfx.