Python - Does Kivy implements activities in the Android apps? - android

As we all know, when developing an Android app in native Java, we use activities. I was wondering that, in developing Android apps in Python(with Kivy), does Kivy implements activities for the apps in itself or not? because I don't see any activity implementation on the sample codes.
If it doesn't implement activities, Do we lose performance or any functionality in the application compared to coding in native Java?

Simply put, you can use Activities (starting them using pyjnius), but not really define them, at least, it's not usually the way one work with kivy.
Kivy doesn't adjust its way of working for targetted platform, it uses its own systems, and make them work there. For what i know the advantages of separating Activities on android is just a way to make your code more neatly organized, and doesn't imply performance changes. It can allow you to start your app in various ways (from a share, for example) but you can do that with p4a/buildozer too, by dispatching messages about the intent, if you need to. With kivy, you'll organise your code like you would do for any python project, using modules.

Kivy is a great tool for developing Android Apps. The best advantage of using Kivy is that it is cross platform and the same project can be used to publish apps on mutti-platforms.
However , it has some performance related disadvantages(as do most cross-platform tools like unity , cocos etc). If you're developing only for Android , I'd suggest taking a look into development tools which use Java. This will help create a smaller APK file which in turn helps in better user retention.
I guess you are real loyal fan of Python, but I have to tell you about its advantage and disadvantage.
Advantages
Pure python and its almightiness is in your hand.
Relatively simple to deploy with buildozer without any need to dive too deep into the details of particular platform.
You can run your app on desktop also, so there is no need to install some extra emulators/VMs to get it work
Disadvantages
Not that much information in Internet, even on stackoverflow
Pretty messy documentation
No obvious way to test the application
Not obvious machanisms of placing widgets, especially in built in layouts, which causes situations like: you want place widget in the center of it's parent, but kivy places it anywhere but not where you want it to be.
Official examples are quite ugly, so you may get false vision of how your application could look like.

Related

Advice on the best way to go about developing an app for Android and iOS as first project

Sorry if the title wording is not clear enough. I need to deploy a very simple app on Android and iOS for a partner company (app does not need to be in App Store or Google Play) to control some machinery via bluetooth. Interface needs to be very basic and only contain a couple of buttons and some text labels that display some information (and be able to read a QR code).
We are not a mobile development company, thus I don't have any experience building apps like this, but the required functionality seems simple enough to at least look into what needs to be done.
Now, the problem is that I only know C/C++ and Python (moderate experience with the Qt framework) and am not really willing to learn both Java and Swift. I might consider learning Swift specifically for a simple project like this, seeing as iOS development is very much tied to their platform, but Java is out of the question. I've looked around and there seems to be a way to write both of them in Python and deploy to each platform, but something tells me it's not really worth the incredible amount of problems that could arise. I need your help with some advice on how to handle this project:
Can a cross-platform app be developed with python(or C/C++) and deployed to iOS and Android (thus halving the overall development time) whilst keeping a sufficiently tidy aspect and bluetooth communication?
If not, can I develop an Android app using C/C++ or Python without immense hurdles? I'd prefer Qt as i'm already familiar with the framework, but i suppose anything does it.
When developing an Android app under point 2, is it possible to see how the app looks like without installing it on the phone for every change in code?
Sorry if the post is too long, am really curios how difficult would a task like this be. I dont want to waste my time learning 2 new languages for just this project nor do i want to end up delaying the partner company with beginner problems caused by my scarce knowledge of a new language.
I really wouldn't suggest cross platform for this kind of project. The bluetooth stacks and APIs are going to be tremendously different, minimizing ability to code share. The UI stacks are completely different. Really using anything but the native tools on iOS can be particularly tricky. Python in particular is hard, because its not meant to interact with either platform. C would be easier, as both Java (via JNI) and Swift (via objective C to C bridges) can call C code. However the UI layers of the two are so different that it would only be useful for business logic, I would still recommend writing the UI in the native platforms.
If you were going to try and do cross platform, I'd suggest react native and javascript, merely because it's the most mature of the cross platform products. That said, their bluetooth stack is likely non-existant or poorly developed because its not the type of thing used by many of the type of apps that choose react native, so you'll likely have to dive into the deep end and learn how to make modules.
Given that this is going to be a company specific app not on an app store- do you actually need to support both OSes? Or can it be done on company devices of a single type? Pushing back on that product requirement might be your best bet.

Is it possible to develop mobile keyboard app in flutter

We want to develop mobile keyboard app - (Third party keyboard) that have some unique features (such translate on the keyboard).
We would like to know if there is a way to developed it once both for IOS and Android, with Flutter, or any other solution?
There's a long and a short answer to this. The short answer is basically no, it's not feasible at this time to do this.
The long answer is that it may be somewhat possible but with a fairly large amount of work for you to do. You're going to have to first create and appropriate project type in android and ios, and then import the dart code & set up the build. You may be able to start with a normal flutter application and modify the xcode/gradle builds to match the specifics for ios/android, but I'd guess that's somewhat unlikely. So you'll probably still have to maintain two separate projects, but which could import the same dart library for the UI.
Because Android and iOS use different APIs for their keyboards, you're going to need to write a Platform Plugin or at least method channels which communicate between your app and the native code, for each of iOS and Android. You'll also probably have to embed the flutter view yourself - see this example as I'd bet the normal FlutterApplication etc won't apply.
I'd guess that on android you could probably get this to work eventually with a lot of work (depending on how familiar you are with android, platform channels, and integrating libraries such as flutter's into the build); on iOS you might have luck but it's somewhat conceivable that iOS blocks certain features that flutter needs in the keyboard for performance or security reasons - just guessing from my experiences developing apps in native iOS although I haven't done a keyboard specifically.
That being said, if you do try this I'd be interested to hear the results, and if you were to go about it in a somewhat generic way that could be re-used it would be of great benefit to the flutter community!

React Native & Android?

I'm contemplating on using React Native for a new web app. Is it possible to ship both iOS and Android apps using it?
I know that it's on the roadmap, but it's unclear to me whether it's going to be a separate open-source project (e.g., React Android vs React Native), or just one (e.g., React Native).
TLDR: Most likely you can. But it depends on your use cases.
You can aim for about 80~99+% code reuse (depending on how much Android/iOS native views/modules you use eg. Do you have custom graphics code or low-level TCP networking code; Those can only be done in native code; And expose as API to your JS code. The amount of the platform-specific JS code is actually minimal. Plus you can also use platform check like if (Platform.OS === 'android'){} to solve that) of code reuse, which is pretty nice. Dropbox and other companies have done similar projects: using c++ to build a 'shared' component between iOS and Android project, while implementing most of the UI code in native iOS(Objective-c or swift) and Android(java). But now you are doing C++ with Java and Objective-C or Swift, more language to master, more complexity and more brain juice went down the drain. And it probably took some super tough gymnastic move to make different native code work in both iOS and Android, plus debugging...
React Native just makes it a lot easier to write almost everything in JavaScript. But there is a catch, only about 80% of the JS code could be shared. In the foreseeable future, you still need to write 'platform-specific' JS code for Android and iOS versions.
That's why FB said they aim for 'Learn once, code anywhere' instead of 'run' everywhere.
But it's still very nice other than code reuse(80+% code reuse is still a big improvement comparing to maintaining 2 entirely different versions: Android and iOS ya?)
Cmd +R to refresh the app is a GREAT boost for development speed. Waiting for a big project to compile just makes you felt you were dying inside.
Declarative UI you get for free, because of using React. This is another great plus! As you don't need to 'dig' into your specific UI code that often anymore. Data changed? Just 'flush' it and UI just update accordingly. No brain juice wasted.
I just ported my not so complicated Android React Native App to iOS. And it took me 3 days. The request for and iOS version for the App came as a rather abrupt and unplanned move. So could definitely be even faster had I built the Android with a plan for iOS too. Huge win:)
Another great benefit is able to do hot code push without going through the hellish 1 week app store review process. So no more, "YAY, our app is approved. Let's release. Oh Shiiit. Critical bug and our app keeps crashing(that's gonna keep happening for at least a week before your fix is live). And you have to beg Apple to speed up the process". This is possible because the major part of the code base would be written in JS and with tools like AppHub or CodePush, you could almost instantly deploy code to your users. This is conditionally allowed by Apple.
3.3.2 An Application may not download or install executable code. Interpreted code may only be used in an Application if all scripts, code, and interpreters are packaged in the Application and not downloaded. The only exception to the foregoing is scripts and code downloaded and run by Apple's built-in WebKit framework, provided that such scripts and code do not change the primary purpose of the Application by providing features or functionality that are inconsistent with the intended and advertised purpose of the Application as submitted to the App Store.
Lastly, as an open-source project, project longevity tends to be a concern. Not an issue for React Native. Internally used by(FB Ads Manager) and backed by FB(a dozen FB Engineers?) by Facebook, with close to 500 contributors and 25k Stars, React Native is full of life. Seeing is believing :) (https://github.com/facebook/react-native)
EDIT 1
I realized that I am apparently a bit biased and only talked about the good stuff about React Native. So do checkout https://productpains.com/product/react-native/ and Github issues to have a full picture. It's definitely not silver bullet. That being said, it satisfies most of my use case and I couldn't see me use native iOS or Android anytime soon.
EDIT 2
The Facebook F8 conference app released by Facebook (duh..) is 100% open source and they have a really nice tutorial to show you how you could have both iOS and Android native experience(90% as good as native ?), and at the same time, achieved 85% code re-use. check it out --> https://makeitopen.com
EDIT 3
You may also want to checkout Flutter and its pros & cons :)
It doesn't make sense to have a single codebase if you want a truly native experience. At the moment we have things like NavigatorIOS in React Native which provides an iOS-style UI for navigating between app screens, but if we were to just start using that on Android it wouldn't feel like a true Android app.
Therefore I'd expect to see a NavigatorAndroid component or similar when the time comes, and the same for various other components that behave differently between the platforms.
One benefit that you would get is that any application logic - maybe a store, or your backend interactions - could be written in a JavaScript file and then included by both iOS and Android.
So while you won't get that write-once run-everywhere developer experience from React Native I would expect to see a solution that gives first-class UI on both platforms while encouraging as much reuse as possible. I personally also hope to see strong build tools to help develop and ship on multiple platforms.
React Native for Android has just been released, Android folder will be creating along side with iOS folder upon creating a new project.
Just another tip as NavigatorIOS was mentioned. Facebook are not really maintaining the code for NavigatorIOS. Instead they are focusing on Navigator.
Yes. We're running it in production with about 5m registered users.
Some things are a little behind iOS but catching up quickly. It's a good wagon to be on.
React Native is designed so that you can deploy to both iOS and Android. There is a caveat, of course.
React Native has supported iOS for much longer, coming to Android only recently. So, there are some differences in terms of what is supported on each platform.
For example, if you place borders on Text, they will show up on iOS, but not on Android. In order to overcome this, you need to place a View around the Text, and apply a border to that. Luckily, React Native makes it easy to integrate separate stylesheets for each platform (or even platform-specific styling on a single stylesheet).
Support for Android is continuously evolving, so it will only be a matter of time before React Native for Android is on par with iOS. Nevertheless, this shouldn't deter you. In my experience, it's a great way to quickly develop for both platforms, and it does save some headaches.
you don't need to maintenance separate code base for android & ios. Actually you can use same code base for build android & ios. I recommend to read the react-native documentation(according to react-native version you are using) before using any inbuilt component in your code.
Eg:- TextInput component onKeyPress function supports for ios only.
if ur are using external lib check these lib support for both ios and android.
Anyway you have to configure external lib separately(install) both android and ios.
hope this will helpful.

Android Homescreen widgets without Java

Is it possible to program and build an Android Homescreen widget without doing it in Java?
For example I imagine it doing this via Cordova/Phonegap or Python Kivy? Is it possible with one of these? Or is there even another way?
You can interact with java from python using pyjnius (a kivy subproject, but it doesn't depend on kivy and can be used without it), including on android calling the apis to create and position native android widgets. For instance, kivy-gmaps is a kivy application that displays and controls a native google maps widget through kivy. I think I've also seen simple examples with webviews, a native android video player, and basic native popups.
Pyjnius is very powerful, and people have raised the possibility of using it to create native java-widget applications via python alone (as opposed to kivy's own opengl interface), but in practice I think there are some technical and practical barriers to overcome and I haven't seen signficant work in that direction. That is, it may well be possible, but nobody has done more than examples like the above yet.
(I assume that by 'Android widget' you mean the widgets of the native java api. Of course kivy has its own widget system that works fine, and the html options like cordova also let you make apps without touching java).

Android UI framework

I have some issues in working with Android layouts and make them adapt for all screen sizes..
I have found that there is an alternative solution : Android Bootstrap http://www.androidbootstrap.com/ for that and provide nice UI components (buttons etc...).
Since I'm developing natively, is this kind of frameworks won't make the App runs slower ?
Is this only a UI framework like for the web (Bootstrap from twitter) ? if not, can we use with it everything in Android (Camera, micro etc...) and Can we include some Jars like Zbar ?
Thank you.
I have found that there is an alternative solution : Android Bootstrap
It is not an "alternative solution". You still will need to be "working with Android layouts and make them adapt for all screen sizes", because Android Bootstrap does not change much related to that.
and provide nice UI components (buttons etc...)
It uses the same Android widget set that all other Android apps use.
is this kind of frameworks won't make the App runs slower ?
There is nothing in an Android Bootstrap project that would necessarily make the app significantly slower.
Is this only a UI framework like for the web (Bootstrap from twitter) ?
It is not even that. It is a starter project that demonstrates how to tie together a dozen or so open source libraries for Android app development. You can think of it as an extended version of the templates used to create new applications and activities in Eclipse or Android Studio.
This is not to say that Android Bootstrap is bad -- far from it. However, it does not resemble your description.
can we use with it everything in Android (Camera, micro etc...)
I have no idea what "micro" is with respect to Android. Since you are writing an Android application, just like any other Android application, you can use it with whatever parts of Android you choose to.
Can we include some Jars like Zbar ?
I see no reason why not.
It is very common for such templating engines not to have exactly most components you need. for android it is basicallly about adding support third party libraries to get the exact experience you need.
Thus you may want to consider adding more or lacking parts by leveraging some external libraries like those from HERE

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