lost zoom position on click with preserveViewport = true

Hi . regrading the following issue https://github.com/openseadragon/openseadragon/issues/1105 that.

when I upload my code I have the following code block to keep the zoom on 2 images :

`var viewer1 = OpenSeadragon({
             id: "id1",
             maxZoomPixelRatio:6,
           defaultZoomLevel: 	0.75,
           minZoomLevel: 	0.75,
           visibilityRatio: 	1,
             preserveViewport: true, 
             prefixUrl: "img",
   });
var viewer2 = OpenSeadragon({
                id: "id2",
                maxZoomPixelRatio:6,
                defaultZoomLevel: 	0.75,
                minZoomLevel: 	0.75,
                visibilityRatio: 	1,
                preserveViewport :true,
                prefixUrl: "img/",
      });

  var viewer1Leading = false;
  var viewer2Leading = false;

  var viewer1Handler = function() {
    if (viewer2Leading) {
      return;
    }

    viewer1Leading = true;
    viewer2.viewport.zoomTo(viewer1.viewport.getZoom());
    viewer2.viewport.panTo(viewer1.viewport.getCenter());
    viewer1Leading = false;
  };

  var viewer2Handler = function() {
    if (viewer1Leading) {
      return;
    }

    viewer2Leading = true;
    viewer1.viewport.zoomTo(viewer2.viewport.getZoom());
    viewer1.viewport.panTo(viewer2.viewport.getCenter());
    viewer2Leading = false;
  };

  viewer1.addHandler('zoom', viewer1Handler);
  viewer2.addHandler('zoom', viewer2Handler);
  viewer1.addHandler('pan', viewer1Handler);
  viewer2.addHandler('pan', viewer2Handler);`

that is work and both image working great together but somthing else with the keep zoom went wrong. I have a button to show and hide on of the image, but in each click of the button i lost some of the zoom event i added preserveViewport = true; in each click or without it so when i click the button i gout the second image and both are got the zoom, but after i click the hide button in the first click everything is ok but if I continue to show and hide the zoom is not at the same point. after 3 or 4 click the zoom return to the start point.

onclick i have the following code

`  var tileSource={
                            type: 'image',
                            url:  img
                      }

                      viewer1.open(tileSource);`

also i have css that i perform on click that divide the div to be 50%(each image is 50%) to show 2 images side by side side so i think maybe its related to css, but how can we keep the zoom event we change divs or with of divs ?

thx for the support

[johnico]

@iangilman hi i opened a new issue with all the details , can you help me there ? https://github.com/openseadragon/openseadragon/issues/1141

the codepen is : http://codepen.io/anon/pen/RpWoar

[iangilman]

Regarding the open event I was thinking something like this:

viewer1.addHandler('open', viewer2Handler); // When Viewer 1 is opened we want Viewer 2 to lead
viewer2.addHandler('open', viewer1Handler);

You shouldn’t need to do anything extra on click, since the zoom and pan events should already cover it.

I’m having a hard time visualizing the scenario where things are breaking. Can you share a link to your code, or maybe a simplified version that shows the problem directly? You can fork my Codepen if you’d like, for instance.