News and views on the world of interactive media from the gskinner team
For many years Flutter has provided the basic “Counter App” each time you created a new project. While that example provides a nice introduction to the foundational concepts of StatefulWidget and basic font/asset management, it does not really resemble the structure of a “complete app”. This has left developers without guidance for anything beyond a basic single page app.
One thing that has always felt a little limiting in Flutter for us has been its inability to perform hit-testing for a button or gesture detector that is outside the parents bounds. This has been a popular issue in the Flutter bug-base over the years, getting something around 150+ upvotes if you add up all incarnations of the issue.
In a previous post we looked at a method for binding directly to the keyboard. While this is handy for quick spikes, or truly global listeners, it is a little dangerous as it is easy to forget to remove these listeners. In this post we’ll look at a couple of different ways to do this a little more safely.
When building a custom UI control in Flutter it’s tempting to just use a GestureDetector and call it a day, but to do so would be a mistake! Especially if you’re planning on supporting users with alternate inputs like mouse or keyboard.
Often when working on a new library or widget, you would like to wire up many temporary testing hooks during development.
Usually in Flutter you would create some buttons, and assign some handlers to trigger all the actions you need. The problem with this is the boilerplate and time required to constantly be writing UI. It takes time, and can clutter up your example code substantially, not to mention the on-screen clutter that half a dozen tappable areas introduces.
Coming from a Unity background, (and also Flash), we were accustomed to using keyboard listeners to quickly test things; only building UI when we actually want to see it. It turns out this is quite easy! Just run on one of the desktop targets and use RawKeyboard.instance.addListener and listen for the keys you are interested in.
While we generally use Provider or GetIt to pass things around in Flutter, there are times when you don’t want to have any dependencies on these libraries, and instead just want to define your own MyFoo.of(context) lookup. Often this is when you’re creating packages yourself.
There are quite a few deep dives tutorials into this around, but in this post we wanted to keep it extremely short and sweet.
With the introduction of NNBD in Dart 2.12, a new keyword was created: late. The primary reason this was created was to allow for non-null fields, that did not have to be immediately initialized.
// Allow this to be null for now, compiler trusts us, that we will assign it.
late final int i;
i = getStartIndex(); // Compiler checks at this point, everything is ok!
i = null; // This will cause an error, compiler is enforcing non-null
This was a necessary feature/workaround for Flutter, because of darts requirement to use const initializers, and most Flutter developers are likely familiar with it by now. In this post we’re going to look at some of the other benefits of late!