Behind the scenes of Triggertrap Mobile's new Solar Calculator

We might be biased, but we’re rather fond of our new Solar Calculator. We’ve asked the team members behind this exciting new tool to tell you about where the idea for the Solar Calculator came from and how they went about delivering it to our users.

First, a brief introduction

In order for us to keep bringing you great new camera-triggering features and an ever-better app, we’ve had to grow our team a little. Meet the bright young chaps responsible for the latest app update and shiny new Solar Calculator...


I’m Rich and I’m the Photography Champion at Triggertrap, working out of the Bristol office. I come from a background as a photographer, and it’s my job to try and make Triggertrap Mobile even better for photographers. I’ve been at Triggertrap for nearly 2 months, and this is the first app I’ve been involved with that’s made it to the App and Google Play stores!


I’m Valentin and I’m the Junior iOS Developer at Triggertrap, Bristol. I have previously worked as a Quality Assurance Engineer where I pointed out flaws to developers. Now I have Rich finding flaws in my work - the irony! My job at Triggertrap is to bring you great new features that you can use to trigger your camera, and also resolve any problems that occur with the app. Hopefully I will find any problems before you do! My latest contribution to the Triggertrap app has been the iOS Solar Calculator.


I'm Scott, the Junior Android Developer here at Triggertrap. Previously I have worked across various platforms and apps but now have the opportunity to focus on Android as my main platform. I spend most of my time on the native Android app, developing new features and fixing any problems that arise! Like Valentin, my first task at Triggertrap was to add the Solar Calculator to the app, which requires the same UI elements but with some twists to suit Android.

The Idea!

The idea was really simple: how can we make shooting sunsets and sunrises easier? A lot of our users like making sunrise and sunset timelapses, but finding out the times for them was always a hassle and involved another app or website. Over a few coffees (and then a few beers) we came to the conclusion that we could show the times in a simple and sexy way that worked really well for as many people as possible.

Platforms and their problems (and solutions!)

iOS: Rotation

As you might have already noticed, the Solar Calculator mode for iOS works in both portrait and landscape mode. This causes the majority of the labels and images to scale depending on the new size of the views that hold them.

The biggest challenge when developing the Solar Calculator for iOS was to animate the sun to follow the arc while at the same time rotate and scale the user interface. To accomplish this - and without going into too much technical detail! - I had to determine a centre point for the arc and position the sun relative to the radius of the arc away from the centre point.

The rotation of the screen is accomplished by constraining the sun, arc and centre point in a view which has equal height and width, with it’s size that is not affected by the device rotation. When the position of the sun relative to the arc is calculated, the view holding the sun and arc is rotated with the sun at the same point on the arc.

 Android: Choosing the design elements

The Triggertrap app has a design language that runs throughout the app; the use of red/grey in active areas and white in static areas. As this was the first calculator to be added, we had to create a new interface specifically for the calculators. Designing the interface to use the usual Triggertrap red sparingly was at the top of our list, keeping it for the core information like the times for sunrise and sunset. This allows readers to glance at the screen and clearly see what is going on, but also allowing for users to clearly see what other information this interface has to share. After some iteration, we came up with what you see today and will hopefully see shortly in the coming months, in more new calculators.

Go home sun, you’re drunk!

Working on the animations was a good challenge for my first month at Triggertrap. What may look simple on your phone actually is made up of quite a few complex calculations and checks to ensure the sun animation doesn't run away off the curve - which it had a habit of doing in it's early iterations! Luckily there is some handy tools in Android which make animating between two points look smooth, only leaving calculating the positions in between to be dealt with.

After dark

An unexpected challenge was working out the best way of showing the sun after sunset. The moon was our first thought, but this wasn’t particularly practical. Firstly, the moon has different different phases, and as we’re not displaying those, we didn’t want to be misleading. We also had to consider the fact we would be showing the moon coming up towards the horizon to represent sunrise, and the moon is also occasionally visible in the morning and afternoon, so we decided against it. In the end we settled on greying out the sun symbol and then flipping the layout to show that the sun is currently below the horizon, and coming back back up!

Finding the local sunset times

The solar calculator uses various geolocating features in your phone to work out where you are, depending on what type of device you own and which services are enabled. As solar events are pretty wide reaching, we could afford to be a bit relaxed with the accuracy (it also saves precious battery!). Having you pinpointed to a location and getting the nearest cell tower location while out and about will only affect the values by the smallest degree, as the times would only significantly differ over larger distances, for example between our lovely offices in Bristol and London.

If you use the calculator while out in the wild without an internet connection, there is a few fail-safes we’ve put in there so the app is still of use. The solar calculator can still work out where you are, but it just can't put a name to the place - like a face you've seen before but can’t remember where. The interface will just display the longtitude and latitude of where you are - this is super accurate but almost impossible to confirm off the top of your head unless you have the superpower to do that... but then why are you taking pictures and not off solving latitude and longitude based crimes?!


Testing the app was great fun! We found a couple of curious bugs, including the sun going for a walk, the app getting a bit confused about which day it was at midnight, and most noticeably, twin suns appearing when we had the location set to Tatooine. After a few rounds of testing, we ironed out the bugs on both apps, and got a build ready for each store, and went and enjoyed a few beers in the sun.

It lives!

The app going live represented one month’s work for us 3 new guys at Triggertrap coming to fruition, and we’re all really proud of our contribution to the app! This project was a great way of learning the codebase for each system, and how things work here, so from here on in we can get things done much faster. Stay tuned for lots more cool things coming in future updates.

Check out the Solar Calculator for Triggertrap Mobile, available for both iOS and Android now! Have any feedback on this new feature? Tell us in the comments below! You can also send your feedback or support queries to