RE: Slow updates

[thomas . deweese]

Hi Minimo,
<[EMAIL PROTECTED]> wrote on 09/17/2008 09:16:15 AM:

> I find something that may interest some of you and I wish you could 
> tell me what you think about my idea.
> 
> I had a look into the node classes and GenericText in particular. I 
> saw that for each setNodeValue, an event is Fired and propaged to 
> parent elements.

   This event let's Batik know that it needs to update the graphics
element associated with the DOM element.

> So in my application I cast my svgDoc to a SVGOMDocument and call 
> setEventsEnabled(false);
> I then loop to perform each single update "without" firing event 
> (they are fired but not taken into account).
> 
> Before the last update I just call setEventsEnabled(true). This line
> allow the last event fred to be taken into account and the tree is 
updated.

> Maybe this method is not the best but it works. Can you tell me what
> you think about this ?

   Since you are modifying multiple DOM element's I don't think the 
above will work.  All but the last element won't be updated on the
screen.

> I'll take this as a solution as I don't have lot of time available 
> but I'd like to discuss about this.

   So the following example SVG seems to be a decent simulation of
what you are trying to do.  After the 'first load' it takes ~32ms on
my machine (to update the text content of 20 text elements).  What
happens for you?  Or why isn't this a good simulation of what you
are trying to do?

<svg version="1.1" xmlns="http://www.w3.org/2000/svg";
     xmlns:xlink="http://www.w3.org/1999/xlink"; x="0px" y="0px"
     width="800px" height="600px" viewBox="0 0 800 600"
     enable-background="new 0 0 800 600" xml:space="preserve"
     onload="update()">
    <script type="text/ecmascript"><![CDATA[
var t0;
var total =20;
function update() {
var i=0;
while (i<total) {
  var e = document.createElementNS("http://www.w3.org/2000/svg";, "text");
  e.setAttributeNS(null, "id", "t"+i);
  e.setAttributeNS(null, "x", "200");
  e.setAttributeNS(null, "y", ""+(20+i*12));
  e.setAttributeNS(null, "text-anchor", "middle");
  var tc = document.createTextNode("test " + i);
  e.appendChild(tc);
  document.getRootElement().appendChild(e);
  i++;
}
setTimeout('change()', 500);
}

function change() {
t0 = System.currentTimeMillis();
var i=0;
while (i<total) {
  var tc = document.getElementById("t"+i).firstChild;
  tc.setNodeValue("change: " + i);
  i++;
}
setTimeout('result()', 0);
}

function result() {
var t1 = System.currentTimeMillis();
var tc = document.getElementById("t0").firstChild;
tc.setNodeValue("result --> " + (t1-t0) + "ms");
}
    ]]></script>
</svg>