Updater
On this page you find the documentation for the GUI Component Updater.
Updater is not an ordinary GUI component. It can be created the same way as a GUI component, but it is not part of the GUI itself. Instead, it is used to dynamically create a child component, and it is the child component that is part of the GUI. So you can't call configuration methods like .size() or .backgroundColor() on the Updater component. Do that on the child component it creates instead.
Introduction
By default, the GUI can only be changed by taking the user to another page (including to the same page the user currently is on), such as when the user clicks on a Button. But, with the Updater component, you can update a part of the GUI on the current page whenever you want, without taking the user to another page.
Example showing what the Updater component can do (in this case updating a Text component to show the current time every second).
childCreator() - Specifying the GUI
Use the configuration method childCreator() to tell the Updater component how it should create the part of the GUI it is responsible for. Pass it a function that creates and returns a GUI component that represent that part of the GUI.
The function you pass to childCreator() will be called immediately when the user comes to the page, but it can also be called at later points in time to create a new version of the GUI for that part.
In this example, the method passed to childCreator() is only called when the user directly comes to to the page, so the usefulness of the Updater component is not shown, but it demonstrated how one can use childCreator().
class StartPage extends Page{
createGui(){
return Rows.children(
Space,
Updater.childCreator(p.createTextShowingClock),
Space,
)
}
createTextShowingClock(){
const now = Time.setNow()
return Text.text(now.getClock())
}
}interval() - Setting the interval
Use the configuration method interval() to tell the Updater component how often it should update the part of the GUI it is responsible for. Pass it the time as the number of milliseconds between the updates.
In this example, the method passed to childCreator() will be called when the user comes to the page, and then also every second after that.
class StartPage extends Page{
createGui(){
return Rows.children(
Space,
Updater.interval(1000).childCreator(p.createTextShowingClock),
Space,
)
}
createTextShowingClock(){
const now = Time.setNow()
return Text.text(now.getClock())
}
}name() - Manually triggering updates
Use the configuration method name() to give your Updater component instance a name. You can then call the function runUpdater() and pass it the same name whenever you want the Updater to update its GUI.
Triggering manual updates of the GUI like this tends to make your code hard to read and hard to understand how it works. If you can implement the same functionality by loading the page anew, that is usually better to do than triggering your own manual updates.
A click on a Button does by default take the user to the next page. If you want a part of the GUI to be updated on the current page instead, you must call the configuration method .stay() on the Button to not take the user to the next page.
In this example, the displayed time is only updated when you click on the Button without reloading the entire page.
class StartPage extends Page{
createGui(){
return Rows.children(
Space,
Updater.name(`refresh`).childCreator(p.createTextShowingClock),
Space,
Button.text(`Refresh`).stay().onClick(p.handleButtonClick)
)
}
createTextShowingClock(){
const now = Time.setNow()
return Text.text(now.getClock())
}
handleButtonClick(){
runUpdater(`refresh`)
}
}