[[development-embedding-visualizations]]
=== Embedding Visualizations

There are two different methods you can use to insert a visualization in your page.

To display an already saved visualization, use the `VisualizeLoader`.
To reuse an existing visualization implementation for a more custom purpose,
use the Angular `<visualization>` directive instead.

==== VisualizeLoader

The `VisualizeLoader` class is the easiest way to embed a visualization into your plugin.
It will take care of loading the data and rendering the visualization.

To get an instance of the loader, do the following:

["source","js"]
-----------
import { getVisualizeLoader } from 'ui/visualize/loader';

getVisualizeLoader().then((loader) => {
  // You now have access to the loader
});
-----------

The loader exposes the following methods:

- `getVisualizationList()`: which returns promise which gets resolved with a list of saved visualizations
- `embedVisualizationWithId(container, savedId, params)`: which embeds visualization by id
- `embedVisualizationWithSavedObject(container, savedObject, params)`: which embeds visualization from saved object

Depending on which embed method you are using, you either pass in the id of the
saved object for the visualization, or a `savedObject`, that you can retrieve via
the `savedVisualizations` Angular service by its id. The `savedObject` give you access
to the filter and query logic and allows you to attach listeners to the visualizations.
For a more complex use-case you usually want to use that method.

`container` should be a DOM element (jQuery wrapped or regular DOM element) into which the visualization should be embedded
`params` is a parameter object specifying several parameters, that influence rendering.

You will find a detailed description of all the parameters in the inline docs
in the {repo}blob/{branch}/src/ui/public/visualize/loader/loader.js[loader source code].

Both methods return an `EmbeddedVisualizeHandler`, that gives you some access
to the visualization. The `embedVisualizationWithSavedObject` method will return
the handler immediately from the method call, whereas the `embedVisualizationWithId`
will return a promise, that resolves with the handler, as soon as the `id` could be
found. It will reject, if the `id` is invalid.

The returned `EmbeddedVisualizeHandler` itself has the following methods and properties:

- `destroy()`: destroys the underlying Angular scope of the visualization
- `getElement()`: a reference to the jQuery wrapped DOM element, that renders the visualization
- `whenFirstRenderComplete()`: will return a promise, that resolves as soon as the visualization has
  finished rendering for the first time
- `addRenderCompleteListener(listener)`: will register a listener to be called whenever
  a rendering of this visualization finished (not just the first one)
- `removeRenderCompleteListener(listener)`: removes an event listener from the handler again

You can find the detailed `EmbeddedVisualizeHandler` documentation in its
{repo}blob/{branch}/src/ui/public/visualize/loader/embedded_visualize_handler.js[source code].

We recommend *not* to use the internal `<visualize>` Angular directive directly.

==== `<visualization>` directive
The `<visualization>` directive takes a visualization configuration and data.
It should be used, if you don't want to render a saved visualization, but specify
the config and data directly.

`<visualization vis='vis' vis-data='visData' ui-state='uiState' ></visualization>` where

`vis` is an instance of `Vis` object. The constructor takes 3 parameters:

- `indexPattern` <string>: the indexPattern you want to pass to the visualization
- `visConfig` <object>: the configuration object
- `uiState` <object>: uiState object you want to pass to Vis. If not provided Vis will create its own.

`visData` is the data object. Each visualization defines a `responseHandler`, which defines the format of this object.

`uiState` is an instance of PersistedState. Visualizations use it to keep track of their current state. If not provided
`<visualization>` will create its own (but you won't be able to check its values)

*code example: create single metric visualization*
["source","html"]
-----------
<div ng-controller="KbnTestController" class="test_vis">
  <visualization vis='vis' vis-data='visData'></visualize>
</div>
-----------
["source","js"]
-----------
import { uiModules } from 'ui/modules';

uiModules.get('kibana')
.controller('KbnTestController', function ($scope) {
  const visConfig = {
    type: 'metric'
  };
  $scope.vis = new Vis('.logstash*', visConfig);
  $scope.visData = [{ columns: [{ title: 'Count' }], rows: [[ 1024 ], [ 256 ]] }];
});
-----------

<visualization> will trigger `renderComplete` event on the element once it's done rendering.
