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Updated 26 October 2021
In this blog, we will learn about Secondary Display Control via Android Presentation Class.
Well, the title line certainly deals with a lot of words that probably most of the developers are not aware of and frankly, even I was not aware of this beauty of Android until last month.
Before we start, let me just tell you a few practical use cases for what you can build after following along.
After reading this blog you will also be able to build something similar.
Before we start talking about code let’s just clear what the words in the title are.
A display is referred to as a screen or area which can show the content.
As a result, an Android device can control any number of displays.
The main point to note is that the application’s code should be able to handle each display separately and these are in sync with the main display.
This display refers to the actual screen provided by the manufacturer of the Android device.
Hence, this screen listens to all the user interactions, gestures and motions events.
As a result, this display is referred to as Main Display.
This display refers to a secondary screen which is somehow (Bluetooth, wired connections, RFC) connected to your Android device.
By Default, this screen is not user interactive and hence it is called as Display and not Screen.
A presentation is a special kind of dialog whose purpose is to present content on a secondary display. A Presentation is associated with the target Display at creation time and configures its context and resource configuration according to the display’s metrics. — developer.android.com
A presentation is a special kind of dialog whose purpose is to present content on a secondary display. A Presentation is associated with the target Display at creation time and configures its context and resource configuration according to the display’s metrics.
— developer.android.com
For Simple understanding, we need to extend this class to build a view to display on our Secondary Display.
With this understanding, now you can do anything you want on Secondary Display.
Now, in this blog, we will just be making a Welcome TextView on the Secondary Display.
File Name –> secondary_display.xml
File Name –> SecondaryDisplay.java
With the help of lines below, you can set the Secondary Display Content.
Last Step:
With this last change, you have completed the task.
Now, just run your application on a device with Secondary Display and see the magic.
Keep coding and Keep Sharing 🙂
References –> https://developer.android.com/reference/android/app/Presentation
https://developer.android.com/reference/android/view/Display.html
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You can easily try this option in any android device or emulators.
All you need to do is to enable the developer options.
Then in the developer options menu find the option “Simulate secondary displays”.
From the list that opens up , you can easily select the width option as per your need.
I am assuming that by control you want to listen to some of the events on the secondary display.
So, if that is all about majorly click listeners then you can add them as you add it to any of the views in your code in your secondary display class as well.
Though, I have not practically implemented any listeners for the secondary display.
But i guess, this should work fine.
Still, if you are looking for soemthing else, then feel free to type more over here.
Regards, Anchit
If you know the solution then please let me know.
Thanks, Sunil
I would need access to your code and then only i can help you out.
This seems to be pretty easy.
You can either create some method in your secondary display class and update the ui accordingly.
Or
You can declare the components public and then access the same in the main activity.
Both will work.
I personally have not worked on automotive AVD.
As per me the connection to secondary screen in AVD will depend totally on how both of the screens are connected.
If the connection is physically wired, then you can also go with the points mentioned in the article.
Regarding mailing details, please do send your query to [email protected]
To do this should I call presentation in all activities? Or can I call it from base activity?
i would recommend you to call in the base activity.
when you need to change the content on the secondary display just override the activity.
your welcome
while running this example on emulator. looking forward for your help.
Hi,
For both points, please first check that the secondary display is fully simulated on your emulator.
If you are able to successfully simulate the dual-screen, then the article is good enough to work like a charm.
Please do share the same.
Your Welcome
also my project is library based where one base project and other modules are divided into libraries. so how to handle this kind of structure?
Hi there,
Yes, we can capture user input and interaction if the secondary hardware supports it.
Sorry, I can’t share samples right now but this is possible with simple logic.
For library-based project, i would recommend adding this functionality to the base project itself so that you can use it on the go in different libraries as per the use case.
Rest all can be done as per your project’s requirement.
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