Aurelia: resize/layout change event for view?

Question

Is there a way to subscribe to a view in order to observe resize/layout events in Aurelia? I have a canvas I would like to resize. I'm wondering if there is an "aurelia" way to do this?

I tried:

<div ref="canvasContainer" class="widget-dial-container" resize.delegate="doresize()">
  <canvas ref="canvas" class="widget-dial-canvas" />
</div>

but it never calls my doresize() method.

I've tried binding to the DOM offsetWidth and offsetHeight, but this doesn't work either (with and without @bindable canvasContainer; in the vm)

Answer 1

The resize event is only supported on the window itself, as Kruga mentioned. You can attach to it in a cross-platform fashion using the Aurelia Platform Abstraction Layer's PLATFORM object. You'll have to run jspm install aurelia-pal to get it. If you aren't worried about cross-plat, then you can just use the window object.

The following template and VM work for me. I implemented a throttle on the resize timer:

HTML

<template>
  <div style="height: 125px; min-width: 150px; width: 100%;" ref="canvasContainer">
    <canvas ref="canvas" width.one-way="canvasContainer.offsetWidth"></canvas>
  </div>
</template>

TEMPLATE

import {PLATFORM} from 'aurelia-pal';

export class App {
  resizeTimer = null;
  resizeEventHandler = () => this.resized();

  attached() {
    this.resized();

    PLATFORM.global.addEventListener("resize", this.resizeEventHandler);
  }

  detached() {
    PLATFORM.global.removeEventListener("resize", this.resizeEventHandler);
  }

  resized() {
    clearTimeout(this.resizeTimer);

    this.resizeTimer = setTimeout(() => {
      let ctx = this.canvas.getContext("2d");

      ctx.fillStyle = "green";
      ctx.font = "30px Arial";
      ctx.fillText(`Width: ${this.canvas.width}`,10,50);
    }, 150);
  }
}