Re: Mixing Elemental2 with GWT Widgets

Excellent!  Will be good to have some company on the Elemental2 journey.  🙂

While I'm sharing...  I wrote a method to load an HTMLImageElement from a base64 encoded string:

public static void loadImage(String imgBase64, Consumer<HTMLImageElement> loaded) {
  HTMLImageElement img = (HTMLImageElement)DomGlobal.document.createElement("img");

  img.onload = e -> {
    loaded.accept(img);
    return null;
  };

  img.onerror = e -> {
    DomGlobal.console.error("Failed to load image.");
    return null;
  };

  img.src = imgBase64;
}

What I don't understand is why onload and onerror need a return value?  I just return null as I've no clue what the return value should be.

On Thursday, 31 July 2025 at 4:20:40 pm UTC+10 Ralph Fiergolla wrote:

Craig! 

Don't worry - i am following your Elemtal2 Experience closely. It is on my to-do list for quite some time now. Thanks for sharing! 

Ralph 

Craig Mitchell <ma...@craig-mitchell.com> schrieb am Do. 31. Juli 2025 um 02:37:

On the off chance someone reads the above post and thinks Elemental2 isn't very good.  Just to make it clear, Elemental2 is awesome.  Just now I needed a WeakHashMap.  GWT said no.  Elemental2 said sure can, with JsWeakMap.  Love it!

On Wednesday, 30 July 2025 at 2:34:49 pm UTC+10 Craig Mitchell wrote:

I've switched to use Elemental2 for a few things.  The rest of my app still uses the standard GWT widgets.

I can bind directly to the Elemental2 elements from the GWT UI Binder, however, if I programatically want to add an Elemental2 element to a GWT Widget, there doesn't seem to be a direct way to do this.

Eg: How would you add the Elemental2 HTMLCanvasElement, to a GWT SimplePanel using its setWidget method?

To work around this, I created an "Elemental2Widget":

import com.google.gwt.dom.client.Element;
import com.google.gwt.user.client.ui.Widget;
import jsinterop.base.Js;

public class Elemental2Widget<T> extends Widget {
  public Elemental2Widget(T elemental2Widget) {
    Element element = Js.cast(elemental2Widget);
    setElement(element);
  }
  public T getElemental2Widget() {
    return Js.cast(getElement());
  }
}

Now I can call it like this:

simplePanel.setWidget(new Elemental2Widget<>(htmlCanvasElement));

Is this how people mix Elemental2 with GWT widgets?  Or is there a better way?

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