A large percentage of examples that I find online inherit from AppCompatActivity rather than Activity. Is this really what I should be doing? I have heard that Activity is newer, and it is my preference. I am currently attempting to learn to use CameraX, and there are very few examples & support that I have been able to find for Xamarin.Android. After finding the following Android tutorial & a translation of it for Xamarin.Android:
https://developer.android.com/codelabs/camerax-getting-started
https://github.com/DottorPagliaccius/Xamarin.CameraX
However, the first parameter of BindToLifecycle seems to like AppCompatActivity but not Activity. Does anybody know what changes I need to make in order to be able to use Activity instead of AppCompatActivity?
Actually, AppCompatActivity is newer than Activity. AppCompatActivity supports some of the newer platform features on older Android devices. Some of these backported features include: Using the action bar, including action items, navigation modes and more with the setSupportActionBar(Toolbar) API.
But don't be worry about trouble of using AppCompatActivity.It's similar to usage of Activity. You said that the first parameter of BindToLifecycle seems to like AppCompatActivity but not Activity. In fact, you can treat it like Activity to use.
// Bind use cases to camera
cameraProvider.BindToLifecycle.
(this, cameraSelector, preview, imageCapture, imageAnalyzer);
For more details about AppCompatActivity and Activity, you can check: https://stackoverflow.com/questions/31297246/activity-appcompatactivity-fragmentactivity-and-actionbaractivity-when-to-us#:~:text=The%20differences%20between%20them%20are%3A%20Activity%20is%20the,Based%20on%20FragmentActivity%2C%20AppCompatActivity%20provides%20features%20to%20ActionBar.
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Being new to flutter and dart, I am looking for ways to structure my projects. I have found that the Repository pattern made its way to dart (I have a strong Java background), but I have found that there's not the necessary tools yet to properly implement a repository.
How I would normally approach this is to first create the simple straightforward methods. I ended up with the following dart code:
abstract class CategoryRepository {
Future<List<Category>> getCategories();
Future<Category?> getCategoryById(String id);
}
All is good. But now imagine I have a PostRepository, and I only want to return posts of a specific category? I am missing a standardized way in flutter how to add conditions to my repository select methods. I cannot believe nobody has written something for this purpose before so I am doubting whether I am on the right track here. Maybe my Java background is throwing me off.
In Java (specifically Spring JPA) I am used to specifications, predicates and criteria as documented here.
In .NET you can implement select methods of a repository pattern with the Expression class which allows you to use LINQ to add select criteria as documented here.
For Flutter or Dart, what would be the equivalent? Or am I on the wrong track?
I have found the flutter_repository package, but it is deprecated (without a reason). Looking at the documentation it indeed had Specifications which are used to add conditions. This would be exactly what I expect/need, but again it's deprecated.
This is where I cannot find the information publicly anymore and am questioning "how to properly implement repository in flutter/dart", hence the reason for posting this.
I'm trying to learn to write Hardware Abstraction Layer (HAL).
Here's the path I've taken so far, please correct me if I'm off in any step.
Downloaded AOSP and built it successfully (86%)
Located Vehicle Hal Support Library
Located android.hardware.automotive.vehicle C++ code.
Things I've attempted after that the steps below without succeeding to get those above classes recognized.
Import android.hardware.automotive.vehicle classes in Android Studio for a typical Android App that targets 29 Api Level.
Adding meta tag of android.car app
Copy/Pasting all source code under AOSP /packages/services/Car/
Partially contemplated adding android.hardware.automotive.vehicle#2.0.so Library and trying to access it through JNI (Not so sure about this one).
Please orient me, I see some repositories on github not doing anything special and somehow they're able to import the package in a java class like this.
import android.hardware.automotive.vehicle.V2_0.VehicleHwKeyInputAction;
import android.hardware.automotive.vehicle.V2_0.VehiclePropValue;
import android.hardware.automotive.vehicle.V2_0.VehicleProperty;
import android.hardware.automotive.vehicle.V2_0.VehiclePropertyAccess;
Here
how on earth do they get access to those classes?
Thanks
Vehicle HAL is not meant to be accessed directly from apps. Car Service does that for you.
You have couple options depending on what you're actually trying to accomplish:
Learn to write HAL services - it's like writing a driver for a given hardware (in this case, something that provides car data to Car Service).
Learn to write HAL clients - try modifying EmbeddedKitchenSink app first. Please note you need to build it with AOSP and not in AmdroidStudio since this is a system app (and regular apps doesn't have access to the HAL)
Learn Vehicle APIs - that's what you need car lib for. Details on how to use it: https://stackoverflow.com/a/63321234/14759774
Looks like Flutter for Web and Flutter for Mobile have to exist as separate projects due to the imports.
Example:
import 'package:flutter_web/material.dart
vs
import 'package:flutter/material.dart';
Is there anyway to build one flutter project with one code base that works for both web and mobile (ios/android)? If not, is this coming?
If so, can you provide an example app?
Would like to just make one code base for the web and mobile and not have to maintain separate projects/code repos.
The OP's question is a bit old and is no longer applicable at the time of posting(7/21/2020). Flutter now has consolidated web into the main flutter package, which prevents us from running into issues with imports like this. flutter_web is no longer a separate package.
However, you may have been able to accomplish this even at the time you posted your question with conditional imports. This answer provides an excellent method of doing this. The following are the essentials of that post:
The core idea is as follows.
Create an abstract class to define the methods you will need to use in general.
Create implementations specific to web and android dependencies which extends this abstract class.
Create a stub which exposes a method to return the instance of this abstract implementation. This is only to keep the dart analysis tool happy.
In the abstract class import this stub file along with the conditional imports specific for mobile and web. Then in its factory constructor return the instance of the specific implementation. This will be handled automatically by conditional import if written correctly.
This method allows for you to do these imports based on platform and applies to all packages that may not support every possible flutter platform(e.g. dart:html, dart:js, dart:js_util, dart:io).
Adapting the MVVMCross framework in Xamarin crossplatform application development, we have PCL (containing Model and View Model) and View (for each platform) as in here.
a) Where does the Xamarin.mobile (for gaining single set of API access) reside? I think inside the PCL. But, i see different binaries for Xamarin.mobile (eg: Android and IOS), do we put all the Xamarin.mobile library inside the PCL? They all have the same name, won't there be any conflict?
b) Where do we keep codes like accessing bluetooth (not available in Xamarin.mobile)? Using MVVMCross decouples the view and business logic, so do all the codes for creating view items after an event has occured (btn click), reside in the view?
c) Where can we use the conditional compilation adapting MVVMCross? I guess in the Model, but is it only used for file access or can it also be used to show view items (toast message on Android) according to the target platform, by placing it on the PCL?
(Excuses if inappropriate, just gathered some information on MVVMCross and Xamarin.mobile and had some reasonings/confusions in mind)
Thank You!
Regards,
Saurav
a) Where does the Xamarin.mobile (for gaining single set of API access) reside? I think inside the PCL. But, i see different binaries for Xamarin.mobile (eg: Android and IOS), do we put all the Xamarin.mobile library inside the PCL? They all have the same name, won't there be any conflict?
Xamarin.Mobile is not portable code - it can't be called directly from PCLs.
For many Xamarin.Mobile functions (and many, many functions which Xamarin.Mobile does not cover) then MvvmCross provides Plugins - you can see some of that in https://www.nuget.org/packages?q=mvvmcross
For the remaining few methods that X.M has but we haven't already included - e.g. contacts lookup - then you can either:
access the Xamarin.Mobile functions by writing a portable interface (a facade) through which to access them
write a new plugin to implement them
For more on plugins:
see N=8 - adding the location plugin - from the N+1 videos in http://mvvmcross.wordpress.com/
for writing a plugin see https://speakerdeck.com/cirrious/plugins-in-mvvmcross
b) Where do we keep codes like accessing bluetooth (not available in Xamarin.mobile)?
Generally this is done the same way as above. For example, for Bluetooth take a look at the Sphero example:
http://blog.xamarin.com/xamarin-developer-showdown-winning-entries-showcase-xamarin-mobile/
https://github.com/slodge/BallControl/tree/master/Cirrious.Sphero.WorkBench/Plugins/Sphero
Using MVVMCross decouples the view and business logic, so do all the codes for creating view items after an event has occured (btn click), reside in the view?
Yes - if it's a 'view concern', then it belongs in the view (this is the same as any Mvvm code)
c) Where can we use the conditional compilation adapting MVVMCross?
I try not to use 'conditional compilation' including #if and partial classes. Sometimes I'll use it in plugin platform-specific modules, but generally I try to use inheritance or abstraction instead - the reason for this is because I use tools like 'refactoring' and 'unit tests' a lot and conditional compilation simply does not work with these.
For more on the benefits (and disadvantages) of using PCLs rather than file-linking and other project-based techniques, see What is the advantage of using portable class libraries instead of using "Add as Link"?
I'm implementing a web application which will support different views according to different browsers. For example, In mobile browsers, it will show a smaller view to users with less UI elements. But we'd like to use same presenters.
I have a solution on hand - adding browser type detecting logic in ClientModule, e.g:
if (browser == "iphone") {
bindPresenter(HomePresenter.class, HomePresenter.MyView.class, HomeView.class, HomePresenter.MyProxy.class);
} else if (browser == "ipad") {
bindPresenter(HomePresenter.class, HomePresenter.MyView.class, IPadHomeView.class, HomePresenter.MyProxy.class);
} else {
bindPresenter(HomePresenter.class, HomePresenter.MyView.class, IPhoneHomeView.class, HomePresenter.MyProxy.class);
}
I'm wondering if it is possible to use some ways like deferred binding in GWT-platform. (but I'd like to follow GWT-plarform's structure rather than adding deferred binding code in xxx.gwt.xml).
So my questions are:
1) Are there any other ways to implement the feature mentioned above?
2) Which way is the best, and why?
Thanks in advance!
Best regards,
Jiakuan W
There is an example in the gwt samples folder that does something like you are wanting. I use a version of the sample code in my project -except using Gin to handle the clientfactory functionality. The sample is called mobilewebapp. It involves using a formfactor method in your .gwt.xml to determine which system you are on - in this case it breaks it down into desktop, mobile, and tablet. Then later in your gwt.xml it trades out client factories based on the form factor - I trade out gin models instead. Here is a link to the source for mobilwebapp
GWT does not allow you to set custom user agent types. You're limited to their set of gecko, gecko1_7, safari, IE6, IE7, IE8, and opera.
That being said, you can access the user agent directly and set your logic to switch accordingly with Window.Navigator.getUserAgent(), or via a property provider.
See this similar question on how to do mobile browser detection in GWT for MVP.
Check the gwtp google group, its a good source, and someone posted a pdf about his efforts regarding the sake problem in there.
Anyway, if I recall correctly, he holds multiple gin modules for each client with the presenters and views, runs custom js code on loading and than installs the correct module on the the ginClinet class.