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Get reference to existing OpenSeadragon Viewer

I need to add an overlay to an existing OpenSeadragon viewer object which isn't created by my code, but elsewhere in the application.
I have got to a point where I know that the viewer has been created as I can access the various html elements that are created via jQuery. However I can't work out if there's any way to create a viewer from an existing reference.
I've tried using the id of the viewer div in:
var viewer = OpenSeadragon(id: "open-seadragon-viewer-id");
but this doesn't seem to work.
Is there any way to do this or can you only get the viewer within the code that initialised it?

Here's one crazy thought... you could monkey-patch some portion of OSD in order to grab the viewer...
var viewer;
var originalIsOpen = OpenSeadragon.Viewer.prototype.isOpen;
OpenSeadragon.Viewer.prototype.isOpen = function() {
// Now we know the viewer!
viewer = this;
// Reinstate the original, since we only need to run our version once
OpenSeadragon.Viewer.prototype.isOpen = originalIsOpen;
// Call the original
return originalIsOpen.call(this);
}
It's kind of tacky, but should work. Note this assumes there is only one viewer on the page... if there are more than one, the same principle could work but you would need to keep track of an array of viewers.
BTW, I'm using isOpen, because it's simple and it gets called every frame. Other functions could work as well.
EDIT: fixed code so we are using the prototype. I still haven't actually tested this code so there may still be bugs!

This solution does not directly answer the question, as it relies on your own code creating the OpenSeaDragon object. It is an implementation of #iangilman's mention of storing the viewer in a global variable. However others may find it useful. (Note that passing a global variable to a function requires a workaround - see Passing a global variable to a function)
The code demonstrates how to use the same OpenSeaDragon object to display different pictures.
var viewer3=null; //global variable
var newURL1='image/imageToDisplay1.png';
var newURL2='image/imageToDisplay2.png';
var elementID='myID';
//the loadScan function will display the picture using openSeaDragon and can be called as many times as you want.
loadScan("viewer3",newURL1,elementID);
loadScan("viewer3",newURL2,elementID);
//the actual function
function loadScan(theViewer,newURL,theID) {
//if object has already been created, then just change the image
if (window[theViewer]!=null) {
window[theViewer].open({
type: 'image',
url: newURL
});
} else {
//create a new OpenSeadragon object
window[theViewer] = OpenSeadragon({
prefixUrl: "/myapp/vendor/openseadragon/images/",
id: theID,
defaultZoomLevel: 1,
tileSources: {
url: newURL,
type: 'image'
}
});
}
}

Creating .json file and storing data in javascript -- using vis.js

In my project I need to save the data to .txt or .xml or .json file. I could not find any answer from vis.js website/issues blog. It might be simple, do not know. Really helpful if anyone help me out with example code. Thank you so much in advance.
function saveData(data,callback) {
data.id = document.getElementById('node-id').value;
data.label = document.getElementById('node-label').value;
clearPopUp();
callback(data);
}

If I understand you correctly, you are looking for a way to save data and options of a graph. In my graph editor adaptation for TiddlyWiki Classic I use the following method to extract data (the full implementation can be found in the repo, see config.macros.graph.saveDataAndOptions, here's a simplified one):
config.macros.graph.saveDataAndOptions = function(network,newOptions) {
newOptions = newOptions || {};
// get nodes and edges
var nodes = network.body.data.nodes._data; // contains id, label, x,y, custom per-node options and doesn't contain options from options.nodes; presumably contains option values set when network was created, not current ones (it is so for x,y)
// no suitable getter unfortunately
var edges = network.body.data.edges._data; // map; for edges to/from? certain node use network.getConnectedNodes(id)
// network.body.data.edges._data is a hash of { id: , from: , to: }
// get node positions, options
var positions = network.getPositions(), // map
options = // get options stored previously
// merge newOptions into options
for(var nodeId in nodes) {
// nodes[nodeId].x is the initial value, positions[nodeId].x is the current one
if(positions[nodeId]) { // undefined for hidden
nodes[nodeId].x = positions[nodeId].x;
nodes[nodeId].y = positions[nodeId].y;
}
storedNode = copyObjectProperties(nodes[nodeId]);
storedNodes.push(storedNode);
}
//# do whatever you need with storedNodes, edges and options
// (pack them with JSON.stringify, store to a file etc)
};
However, while this works ok for storing data, this only helps to save options passed for storing explicitly which can be not very nice for some cases. I use this method in manipulation helpers and on dragEnd (network.on("dragEnd",this.saveToTiddlerAfterDragging), config.macros.graph.saveToTiddlerAfterDragging = function(stuff) { config.macros.graph.saveDataAndOptions(this,{ physics: false }); };). I haven't recieved any better suggestions, though.
If you need to get data and options reactively and setting such helper to handle certain edit events can't solve your problem, then I suggest wrapping nodes, edges and options as vis.DataSet and save those when needed. This is related too.
To answer the question about events/other ways to use such methods. Here's how I use them:
I save data after drag&drop moving of nodes, this is done using an event handler. Namely, I introduced
config.macros.graph.saveToTiddlerAfterDragging = function(stuff) {
config.macros.graph.saveDataAndOptions(this,{ physics: false });
};
(when drag&drop is used, physics should be switched off, otherwise coordinates won't be preserved anyway) and then I use
network.on("dragEnd",this.saveToTiddlerAfterDragging);
so that changes are saved.
As for saving after adding/editing a node/edge, I apply saving not by an event (although it's nice thinking, and you should try events of DataSet, since there's no special graph events for that). What I do is I add an elaborated hijack to the manipulation methods. Take a look at the source I've linked after the
var mSettings = options.manipulation;
line: for each manipulation method, like options.manipulation.addNode I hijack it so that its callback is hijacked to call config.macros.graph.saveDataAndOptions in the end. Here's a simplified version of what I'm doing:
var nonSaving_addNode = options.manipulation.addNode;
options.manipulation.addNode = function(data,callback) {
// hijack callback to add saving
arguments[1] = function() {
callback.apply(this,arguments); // preserve initial action
config.macros.graph.saveDataAndOptions(network); // add saving
};
nonSaving_addNode.apply(this,arguments);
}
The thing is, addNode is actually called when the add node button is clicked; though, I'm using a customized one to create a popup and apply changes once user is happy with the label they chose.

Vis.js network: how to add a node on click inside the canvas?

Manipulation methods of vis.js only include addNodeMode(), but not something like addNode(). I wonder if there's some nice way to create a node on click. May be by manipulating the data instead of network itself?
Of'course, one may go
network.on('click',function(params){
if((params.nodes.length == 0) && (params.edges.length == 0)) {
network.addNodeMode(); // doesn't add, one more click needed
//# generate click in the same place. Use params.pointer.canvas
// or params.pointer.DOM to set appropriate coordinates
}
})
but then we have also to prevent infinit loops since we generate a click event in a click handler..

Ok, here's my current implementation:
...
data = ...
nodes = new vis.DataSet(data.nodes); // make nodes manipulatable
data = { nodes:nodes, edges:edges };
...
var network = new vis.Network(container, data, options);
network.on('click',function(params){
if((params.nodes.length == 0) && (params.edges.length == 0)) {
var updatedIds = nodes.add([{
label:'new',
x:params.pointer.canvas.x,
y:params.pointer.canvas.y
}]);
network.selectNodes([updatedIds[0]]);
network.editNode();
}
})
It's not perfect since it actually creates a node and starts editing it, so if we cancel editing, the node stays. It also creates unwanted shadows of nodes. But it's already a working prototype which is enough to start with.

You can add nodes dynamically by using the update method of the vis.DataSet class. See this documentation page for details: https://visjs.github.io/vis-data/data/dataset.html

can I dynamically set the ID and view name?

<core:mvc.XMLView id="{path:' AssignmentModel>/AssignmentType' ,formatter:'.getViewName'}"
viewName="{path:' AssignmentModel>/AssignmentType' ,formatter:'.getViewName'}"
height="100%" visible="true"/>
I want view to be loaded based on assignemnt type.
I tried to dynamically load the view from controller, based on type.
but that itsnt working as expected.

If you use a View in an XMLView it will be created once. Even if your binding was working it would be OneTime, meaning it is only resolved once, which is obviously not what you are looking for.
You either have to use Routing as qualiture already mentioned or load your content dynamically from your controller and manually insert it in your view hierarchy. You could still use a PropertyBinding to observe property changes like this:
var binding = new sap.ui.model.PropertyBinding("AssignmentModel", "/AssignmentType");
binding.attachChange(function() {
var sViewName = this.getViewName(this.getModel("AssignmentModel").getProperty("/AssignmentType");
var oView = sap.ui.xmlview({
id: sViewName
viewName: sViewName
});
// pack your view whereever you want, clean the old view before
this.getView().addContent(oView);
}, this)
You might need to use sap.ui.model.odata.ODataPropertyBinding depending on the model you are using.
Code above is untested but it 'should' work.
GL
Chris

Get object by its `id` in an AIR windowedApplication

There may be a better way of doing this...so please suggest if there is.
I've got some javascript that calls an AIR function. This AIR functions creates a new HTML element and adds it to the "Stage" like so:
// guid is the ID given to the new window (HTML element) by javascript
private function createNewWindow(guid:String):void {
var frame:HTML = new HTML();
frame.id = guid;
addElement(frame);
}
Now I've also got a function that sets the location of the frame based on its id...this is where I'm struggling.
// set the location of the window referenced by it's id (guid)
private function setLocation(guid:String, location:String):void {
// psuedocode. Obviously it won't work.
stage.getById(guid).location = location;
}
So, how do I "get" my HTML element based on its ID?

Short answer, you don't. This isn't javascript, this is a OO language and as such, you need to change your thought process. What are you trying to do? Create several html windows within an air application? If you want to have an id based approach, you're going to need to store the id and the pointer to the component in an data structure (like a dictionary).
private var _components:Dictionary = new Dictionary();
this._components['someId'] = someComponent;
And from there you can add a function that just saves/returns the components. I'm not entirely sure what's your approach and what you're trying to accomplish, but my gut tells me you're not doing something right.