Category: snapshot

Exporting Qlik Sense extensions to Powerpoint and PDF

Update 2020-06-27: Qlik sense has changed since I originally wrote this, up to date version of using a Promise can be found here:

Printing Qlik Sense extensions

One of the great new features in Qlik Sense is snapshots and storytelling. It allows you to create a snapshot of your visualizations, with the current selection state, and then include the snapshot in a story. Behind the scenes Qlik Sense also uses snapshot for export to PDF, PowerPoint and image. This makes it even more important for you to make your extension work well with snapshots. Sometimes this is however not easy…

The basics

To turn snapshots on, you need to include a few lines in your extension:

This will give you a context menu in the client with alternatives to create snapshot and export the visualization. That might be enough, but it might not be enough. To verify it you should:

  • create a snapshot of your extension, include it in a story and verify that it works
  • export your extension to PDF and/or PowerPoint (possibly also image)
  • and export the story to Powerpoint/PDF

You visualization is actually used in three contexts, that are somewhat different:

  1. the normal analyse mode, with live data, affected by changes in selection state
  2. the snapshot/story mode with a snapshot of data and the selection state as it was when the snapshot was created
  3. the export mode, which is also based on a snapshot, but run in a separate service on the server

To make it actually work in all, you might need to do some more work.

Make Qlik Sense wait for your extension

One problem, mainly in export, is to let Qlik Sense know when your extension actually is ready with the rendering. You might get just an empty area in your powerpoint, or just the header but no content. This might be because the image is taken before your extension is ready.

The mechanism to fix this is a javascript concept called a Promise. Your paint method should return a Promise, that resolves when the rendering is ready. Qlik Sense will then wait until the Promise is resolved and then grab the image.

This is described where briefly in Qlik Sense help under ‘Set up “finished rendering” notification, like this:

This will return a Promise, that immediately resolves. This might not be good enough, since you might want to wait for something until you resolve. In my case, I used highcarts and highcharts has a callback function that will be called when rendering is ready. The final solution is like this:

So, I create a deferred object before calling the Highcharts rendering method. I can then return the promise that belongs to the deferred, but I do not resolve it until Highcharts tells me that rendering is complete, actually I had to add an additional delay of 1 second to make sure. There is currently no documentation of qlik.Promise in Qlik Sense help, but you can look in the angularjs documentation.

Turn animations off

If it’s still not working, you should take a look at animations. Animations in analyse mode are good (if used the right way…) and might help the user discover insights in their data, but in export they should be turned off.

In Highcharts there are actually two flags you should turn off to diable animations. It might be enough to turn off just one of them, but why not both:

The isSnapshot flag which I use to determine if we are in analyse mode or in snapshot (story or export) is undocumented, so this solution might break in future Qlik Sense versions, but in September 2017 it works.

Snapshots and Extensions in Qlik Sense

One of the most popular new features in Qlik Sense is snapshots and storytelling. When you discover something interesting in your Qlik Sense app you can take a snapshot of a visualization, including its selections and data, and then build a story where you use it. And you can recreate the selections from the snapshot and drill deeper into your data or look at it from another angle.

In many cases this works automatically for your extension too, but sometimes it doesn’t. In recent versions of Qlik Sense new features, like printing and export to PDF are also built on the snapshot feature, which makes it even more important for it to work. So here is a description of how it works and what you need to do to make your extension work in snapshots.

How does snapshots work?

You create a snapshot by clicking the camera icon in the visualization context menu.  Qlik Sense will then make a copy of the data used for the rendering, known as the layout. This structure is then included in a new bookmark, that is created in Qix engine. Note that it’s not the HTML that is saved, nor is it a bitmap of the actual visualization on the screen. It’s the data.

So when the user wants to look at the snapshot, the data is loaded from the bookmark, Qlik Sense then checks what extension was used to visualize it, loads the extension, creates an object using the visualization, and calls the paint method of the visualization. But the layout parameter will not contain live data from the current selection state, it will contain data from the snapshot.

What this means for your extension

For snapshots to work your extension should use only the layout when rendering.  You should not try to use the capabilities APIs to access data dynamically. Most likely it will not work, and if you manage to get it working, the data you get will be live and not reflect the state when the snapshot was taken. So make sure you add the data you need to the properties structure instead.

Also you need to keep the layout clean. It is good practice to treat it as read-only, adding nice-to-have references make make it impossible to serialize the layout, and creating the snapshot might fail.

And don’t forget to test creating snapshots from your extensions. Also verify that printing and exporting to PDF works, very likely your users expect them to.