topic Re: Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future? in ArcGIS JavaScript Maps SDK Questions

Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?

RexBradford — Thu, 19 Jan 2012 17:55:19 GMT

I'm just curious if there are any plans to use HTML5 <canvas> elements as an option in layers.

I am exploring creating a custom "feature layer" using a <canvas> overlaid on the map because in my admittedly informal testing it seems much faster for drawing lots of small marker-type images (i.e., a couple of thousand), compared to doing them in a Graphics layer. Complications of this "outside the toolkit" approach include layer stacking (always on top is all I need, but...) and proper mouse event handling (i.e., routing events not handled by the <canvas> layer to the underlying map layers).

Obviously this would require HTML5 browsers, which doesn't include IE 7/8 without use of far slower compatibility add-on libraries, but still it seems like a nice option to have in the toolkit - i.e., if the toolkit could use <canvas> rather than svg optionally for the whole stack of layers.

Are there any plans or tentative plans or experiments in this direction?

Rex Bradford
Direct Relief International

Re: Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?

derekswingley1 — Sun, 12 Dec 2021 00:19:23 GMT

You can already do it!

Since graphics layers (and feature layers) use dojox.gfx to draw shapes, you can explicitly tell dojo to use canvas. This is as simple as specifying canvas for gfxrenderer:

    <script>
      var dojoConfig = { 
        "gfxRenderer": "canvas",
        "isDebug": true,
        "parseOnLoad": true 
      };
    </script>

I've done some testing with this and didn't see huge gains over using SVG. YMMV.

Re: Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?

DonnyVelazquez — Wed, 25 Jan 2012 14:52:39 GMT

The only thing that means is that dojo's implementation of drawing on canvas is slow.

Re: Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?

RexBradford — Fri, 27 Jan 2012 12:17:04 GMT

Thanks. I tried it out and it worked. Though when panning the map the canvas layer didn't redraw at the same time as the base map, which was disconcerting.

There was no obvious performance improvement over svg in my one test, though I didn't try to measure carefully.

Rex

Re: Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?

mingchunfan — Thu, 31 Oct 2013 04:55:57 GMT

hill,I am doing this?
do you have a demo about "Is HTML5 canvas-driven layers part of the ArcGIS javascript toolkit's future?" .