I need to develop web app that will return qr code(or link to qr code) to mobile clients. I plan to learn the basics of GWT because i alredy know java programming.
Is it possible to use zxing libraries or some other java libraries with GWT, so generating (encoding) QR codes could be done with a few lines of code? Or do you suggest any other option?
The QR code that will be returned by server will depend on ID that will come with the request from mobile phone.
Tnx
Generating the QR code in-server using a library such as zxing is a pretty obvious way to go about this an could be absolutely appropriate for your application.
But you might also consider off-loading this to an external web-service such as Google Charts. See here. The advantage of this approach, if it works for you, is that you free your service resources and bandwidth from the responsibility so it would likely scale better and be less complex to develop.
The caveat is, of course, is that your application would have to satisfy the provider's terms of use
Related
I have an app built on React Native whose core functionality is to capture some images, analyse and process the images and return some results. As of now the image analysis was done in the server side using python and opencv. Only the results and the resultant images were returned. Now as per the requirement by the clients, due to privacy concerns, they want the image processing to be done on the mobile app itself. (As the images are medical related and they don't want the images to be sent to the server)
So, my question is, if there is a way I can use my existing python with opencv code and integrate it directly into react-native/android/ios?
Right now what I am doing is using the library react-native-opencv3 , numjs, etc to re-write the algorithm in react-native as I feel comfortable using javascript (I have no experience in swift). However not all opencv, numpy functions are supported by these libraries and it is consuming all the time to re-write the code.
I found about using jython, python-for-android and swift-python-interoperability
Can I use these to directly integrate python opencv code into my current application? If yes, it would be great if someone can help me with some small example or guidelines as I cannot find anything.
Other method that I considered was:
Re-write the algorithm using native code and opencv-android and opencv-ios sdks and create the react-native bridge to call the algorithm. (I am guessing it will take a lot of time as I have to write in 2 different languages. Time that I don't have)
Does anyone know a framework to develop a mobile application for Android with Java and HTML?
I mean develop UI with HTML (to reuse it with an other OS) and native functions with Java.
For the moment I am trying to develop multiplatform apps with Qt but it's quite complex to use native functions from Java, that's why I'm looking for an easier way to do it.
I don't think you can find this kind of framework.
If you meet some problems to use native functions with Qt I recommend you to watch BogDan Vatra videos and pdf
https://www.qtdeveloperdays.com/sites/default/files/BogdanVatra_Extending_Qt_Android_Apps_with_JNI.pdf
Besides, you should look at the QtAndroidNamespace class and runOnAndroidThread function.
Edit : You can find the videos in the Tutorials part of QtCreator
I am not sure about the Java but using javascript,we have alot of Frameworks like Titanium, Sencha Touch and PhoneGap etc.In this you can simply use the html,js,and css3 bundle to creates the IOS Android and as well as web.
I would strongly advise against reusing the UI on different mobile operating systems - it will always look as if it doesn't belong on one of those systems. Creating an Android UI isn't that complicated, you should try it.
That said, you could have just one big WebView on your native UI, displaying your HTML UI. You might need a web server in your app, serving the UI, though - I'm not sure.
First of all I'm a newbie in VoIP implementation. I need to implement VoIP single and group call in android application. Could you tell me, what is actually the best way to achieve this ? I'm looking for Android SIP library (probably open source) which should:
has good documentation with simple app examples
be ready to use with java
Maybe just native android SIP api will be the best ? But I heard that it doesn't support group calls.
Most of the voip libraries use C/C++ implementation for various reasons. You can use PJSip which is a C voip/sip stack. It has a good documentation but you have to build it yourself using android ndk . It has good documentation and also contains processes to build it for Android and other platforms. But there is no java/android wrapping built in so you should do that yourself. Another option is Liblinphone which is also based on C stack but provides all of the wrapping and implementations out of the box so you don't have to bother so much on native codes. It also has a sample application which you can try yourself. One downside of Liblinphone is that it lacks proper documentation and you have to dig in more.
Regarding the android SIP api, I don't think it is a good option as it has much more limitation and hardly maintained. It is based on Jainsip stack which is a 100% java stack but is too verbose. I personally would like to recomment Liblinphone as I am currently implementing it and am pretty satisfied with it. Best of luck...
Update
Here is the source code of linphone for android if you are interested in it. You can get pretty much idea of Liblinphone for android from it. You have to dig much more into the sources though.
You can have a look at Restcomm Android SDK:
It's open source, with an active community around it
It using SIP for signaling and Webrtc for media so should work nicely with NATs, etc
Comes with 2 sample applications that you can play with and alter their code to experiment
Comes with quick start guide, reference doc
You can check the Olympus sample App right away by installing the .apk from this link
Notice that the SDK doesn't support group calling out of the box, but you could combine it with Restcomm-Connect open source platform to add such functionality very easily. Restcomm-Connect also comes with docker, so you should be able to install it right away.
Please let me know if you have any questions
Best regards,
Antonis
I am trying to write a Google App Engine (GAE) Java app to decode QRcodes. Users of my app will send an email to the app with an image containing a QRcode which they want to decode and my GAE app would send a reply with the decoded info. I was planning to use zxing library for this.
Currently I am able to extract the image which came as an attachment in the email. But now to use zxing I need imageIO and BufferedImage classes, which are not part of GAE whitelist. So I am stuck. Can somebody please help me figure out how I can decode a QRcode, with or without zxing?
Google provides their own API for working with images on GAE. You will need to use this API instead of javax.imageio.*. Or rather, since it's your library that makes use of these classes, you'll have to modify the library's source code to work with the GAE classes (or switch to a different library, or write your own). That may be a fairly sizeable job, depending upon how heavily the library relies upon javax.imageio.*.
Edit: Maybe you can refactor your code to use zxing's web-based decoder? That might be simpler than trying to modify their library to use the GAE image API.
I've got a lot of experience in Java but none developing mobile apps. I'd like to write an application using Java/Swing and then convert it for use on an Android phone.
Is this feasible or do I really need to develop from the ground up for the Android platform?
I don't own an Android phone as I can't afford one at the moment, and the Android emulator is so slow that I find myself wasting a lot of time sitting around waiting.
Alot of the code from Java is the same in Android but I would say don't. Android uses its own UI system and it would be hard to transfer from swing. Also when you get deeper into the Layouts the Android system has the application would be completely screwed up. Not to mention the whole Intent, Receiver, Content Provider aspects would not transfer properly. Then you need to think about memory. Simple answer in my opinion... no.
With Intent/Activities, in many ways Android applications need to be designed like web apps with pages connected by links. It's quite a different paradigm, so until you know it well I would develop straight onto Android.
If you use the control-model-view paradigm so that your application logic is separated from your display logic, then you should be able to port your application logic from ordinary Java to Android with few or no changes. As for the display logic, that will have to be rewritten using the Android SDK.
If you consider, J2ME may not support fullest functionality of swings. So, it breaks on the first step. Secondly, Android native development method uses XML for its presentation layer and java for Application and Business layers. If you can write the extending methods for android tags, then you may achieve your target at the basic level.
Rather I suggest use the phonegap and develop everything in HTML5, DOJO and CSS3. This would work on any mobile, any platform.