topic Re: What event can I tap into to wait for the view to finish drawing after basemap toggle? in ArcGIS JavaScript Maps SDK Questions

What event can I tap into to wait for the view to finish drawing after basemap toggle?

JackFairfield — Tue, 19 Nov 2019 21:24:31 GMT

I am trying to wait for the view's basemap to update and finish drawing after a basemap toggle event. Is there a good consistent way to wait for the complete rendering of the map before trying the screenshot? I was thinking of watching the "updating" property on the basemap layerviews, but this seems cumbersome. Also, if I have many feature layers, would I have to watch the "updating" property on all layers before safely using the take screenshot function?

Here is a JSBIN showing a quick example of what I am talking about. Click the basemap toggle to see what I am referring to.

Re: What event can I tap into to wait for the view to finish drawing after basemap toggle?

RobertScheitlin__GISP — Tue, 19 Nov 2019 21:39:31 GMT

Jack,

Just watch the views updating property

Re: What event can I tap into to wait for the view to finish drawing after basemap toggle?

JackFairfield — Tue, 19 Nov 2019 22:13:05 GMT

I've tried this and it seems to only work sometimes.

Here is a sample updated JSBIN

In this example, after toggling a few times, the screenshot is sometimes black. Am I doing something wrong?

Thanks for your response.

Re: What event can I tap into to wait for the view to finish drawing after basemap toggle?

Noah-Sager — Tue, 19 Nov 2019 23:34:08 GMT

I downloaded and ran the app locally, and it seemed to work consistently. Perhaps there's some network or synchronicity issue at play.

Re: What event can I tap into to wait for the view to finish drawing after basemap toggle?

UndralBatsukh — Sat, 11 Dec 2021 07:49:25 GMT

Hi there,

I am able to reproduce the issue you described. It appears that `view.updating` value changes several time during basemap swapping. So the `view.takeScreenshot()` is called several times and the images sometimes get returned out of order. I created an issue for this.

In meantime, please add a setTimeout before you call takeScreenshot and this will ensure you get the right image.

view.watch("updating", async (val) => {
  if (!val) {
    setTimeout(function(){
      view.takeScreenshot().then(function(screenshot){
        screenshotDiv.src = screenshot.dataUrl;
      });
    }, 500);
  }
 });‍‍‍‍‍‍‍‍‍

-Undral