I am using VS Code.
Supposedly there is a function called inspect() in dart that allows you to vardump an object.
my barebones example is as follows:
import 'dart:developer';
class User {
String name;
int age;
User(this.name, this.age);
}
void main() {
User newUser = User("Steve", 30);
inspect(newUser);
print('done');
}
I don't get any errors, but all I see in the Debug Console is "done"
On this page there is am image showing inspect() sample output (4th image from the top) in the Debug Console:
Link
Is there something else I need to do to make this command work in VS Code?
Related
I'm trying to add the learning_text_recognition library to my Flutter project. I was able to get the example in the API docs to work with no problems (https://pub.dev/packages/learning_text_recognition/example), but now I'm trying to add it to my own project using the information found on the Readme tab of the same website. It's slightly different than how the example worked and I'm now receiving several errors that I didn't receive in the example. Specifically, the errors are on the following line:
RecognizedText result = await textRecognition.process(image);
It says that the await function can only be used in an async function, but I don't know if I should make the function or the class async? It also says that the method 'process isn't defined for the type 'TextRecognition', but I don't know what the method should be, since that part worked perfectly fine in the example. It was also complaining that image wasn't defined, but I just created a variable called image with InputCameraView, which seemed to work.
I've tried moving the code into a new function and made an image variable. This is what the code looks like now:
getInfo(){
var image = InputCameraView(
canSwitchMode: false,
mode: InputCameraMode.gallery,
title: 'Text Recognition',
onImage: (InputImage image) {
// now we can feed the input image into text recognition process
},
);
TextRecognition textRecognition = TextRecognition();
RecognizedText result = await textRecognition.process(image);
}
I've also included the following import statements:
import 'package:learning_input_image/learning_input_image.dart';
import 'package:learning_text_recognition/learning_text_recognition.dart';
import 'package:provider/provider.dart';
I'm not sure if I'm maybe missing a step?
Your function should have the async keyword to indicate that there will be wait points. See the dart async/await documentation.
Another detail for the example InputCameraView is a widget, it should not be inside the function. It must be using the onImage method of the InputCameraView to collect the recognition and the builder to build it. In the doc onImage calls the async function _startRecognition to collect the data you must do something in this line.
void getInfo() async {
var image = InputCameraView(
canSwitchMode: false,
mode: InputCameraMode.gallery,
title: 'Text Recognition',
onImage: (InputImage image) {
// now we can feed the input image into text recognition process
},
);
var textRecognition = TextRecognition();
var result = await textRecognition.process(image);
}
TL;DR how can I have an Android sensor permanently running/active/registered for my app, even if I close it?
Objective:
I'm making a Flutter application that counts your steps using the pedometer package,
which uses the built-in sensor TYPE_STEP_COUNTER of Android,
which returns the # of steps taken since last boot (iOS). On Android, any steps taken before installing the app are not counted.
How I implemented it:
When the app is actively running in the foreground, each step causes
a myStepCount to increment by 1.
In all other cases (phone locked, went to home-screen, closed the app...), the android TYPE_STEP_COUNTER sensor should
still be running in the background, and once I open my app again, the
difference between new stepCount and last saved stepCount (saved
using shared_prefs) will be calculated and added to myStepCount.
Important:
The TYPE_STEP_COUNTER sensor must be permanently running/stay registered in the background, even after I lock my phone, go to the home-screen, or close the app...
Observations:
On my Samsung Galaxy A02s, my app works perfectly fine, as it it supposed to
(as described above). That is because on that phone I also have the
Google Fit app installed, which tracks your steps 24/7 (so the
TYPE_STEP_COUNTER sensor is permanently registered).
On my Samsung Galaxy S7, my app does not work as it's supposed to.
myStepCount gets incremented when I take steps while the app is
running in the foreground. But steps taken while the app is closed
will NOT be added to myStepCount once I open the app again.
Note: I don't have any other step-counting-apps like Google Fit on this phone.
Conclusion:
I need to find a way to register the TYPE_STEP_COUNTER sensor from my Flutter app, and keep it registered even after I close the app.
2 Attempted (but unsuccessful) Solutions:
1st Attempt:
Calling Native Android Code from my Flutter Code to register the sensor
This is my main.dart file (with the unimportant parts left out for simplicity):
void main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(App());
}
class App extends StatefulWidget {
#override
_AppState createState() => _AppState();
}
class _AppState extends State<App> with WidgetsBindingObserver {
#override
void initState() {
super.initState();
if (Platform.isAndroid) {
_activateStepCounterSensor();
} else if (Platform.isIOS) {
//TODO check if anything is needed to to here
}
}
void _activateStepCounterSensor() async {
MethodChannel _stepCounterChannel = MethodChannel('com.cedricds.wanderapp/stepCounter'); //convention
dynamic result = await _stepCounterChannel.invokeMethod('activateStepCounterSensor');
switch (result) {
case "success":
//The following line gets printed when I run the flutter app on my Samsung Galaxy S7:
print('_activateStepCounterSensor(): successfully registered step counter sensor for android');
break;
case "error":
print('_activateStepCounterSensor(): failed to register step counter sensor (not available) for android');
//TODO display errorpage (because app is completely useless in this case)
break;
default:
print('_activateStepCounterSensor(): unknown result: $result');
break;
}
}
//build() and other lifecycle-methods and helper methods: not important for this question
}
This is my MainActivity.kt file:
package com.cedricds.wanderapp
import android.content.Context
import android.hardware.Sensor
import android.hardware.SensorEvent
import android.hardware.SensorEventListener
import android.hardware.SensorManager
import android.util.Log
import android.widget.Toast
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel
class MainActivity2: FlutterActivity(), SensorEventListener {
private val STEP_COUNTER_CHANNEL = "com.cedricds.wanderapp/stepCounter";
private lateinit var channel: MethodChannel
override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
super.configureFlutterEngine(flutterEngine)
channel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, STEP_COUNTER_CHANNEL)
channel.setMethodCallHandler { call, result ->
when(call.method){ //this is like switch-case statement in Java
"activateStepCounterSensor" -> {
activateStepCounterSensor(result)
}
}
}
}
private var sensorManager : SensorManager?=null
private var sensor: Sensor ?= null
private fun activateStepCounterSensor(result: MethodChannel.Result) {
//This line gets printed when I run the flutter app, so the method gets called successfully:
Log.d("Android", "Native Android: activateStepCounterSensor()")
sensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
sensor = sensorManager?.getDefaultSensor(Sensor.TYPE_STEP_COUNTER)
if (sensor == null) {
Toast.makeText(this, "missing hardware.", Toast.LENGTH_LONG).show()
result.error("error", "error", "error")
} else {
sensorManager?.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL)
//This line gets printed:
Log.d("Android", "Native Android: registered TYPE_STEP_COUNTER")
//and never unregister that listener
result.success("success")
}
}
override fun onSensorChanged(p0: SensorEvent?) {}
override fun onAccuracyChanged(p0: Sensor?, p1: Int) {}
}
Despite the few print(...) and Log.d(...) being printed in the console as expected, the app doesn't work how I expected it to work. When I exit the app, walk for example 50 steps, then open the app again, those 50 steps are missing. It seems the sensor is being unregistered somewhere.
2nd Attempt:
Modifying the pedometer package's code by removing unregisterListener(...):
The only changes I did to the file were 2 Log.d(...) statements and more importantly, commenting out a specific line of code.
modified SensorStreamHandler.kt from the pedometer package:
package com.example.pedometer
import android.content.Context
import android.hardware.Sensor
import android.hardware.SensorEventListener
import android.hardware.SensorManager
import android.os.Looper
import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.EventChannel
import android.os.Handler
import android.util.Log
class SensorStreamHandler() : EventChannel.StreamHandler {
private var sensorEventListener: SensorEventListener? = null
private var sensorManager: SensorManager? = null
private var sensor: Sensor? = null
private lateinit var context: Context
private lateinit var sensorName: String
private lateinit var flutterPluginBinding: FlutterPlugin.FlutterPluginBinding
constructor(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding, sensorType: Int) : this() {
this.context = flutterPluginBinding.applicationContext
this.sensorName = if (sensorType == Sensor.TYPE_STEP_COUNTER) "StepCount" else "StepDetection"
sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as SensorManager
sensor = sensorManager!!.getDefaultSensor(sensorType)
this.flutterPluginBinding = flutterPluginBinding
}
override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
Log.d("Pedometer", "Native Android: onListen()")
if (sensor == null) {
events!!.error("1", "$sensorName not available",
"$sensorName is not available on this device");
} else {
sensorEventListener = sensorEventListener(events!!);
sensorManager!!.registerListener(sensorEventListener, sensor, SensorManager.SENSOR_DELAY_NORMAL);
}
}
override fun onCancel(arguments: Any?) {
Log.d("Pedometer", "Native Android: onCancel()")
//The only change I did: commenting out the following line:
// sensorManager!!.unregisterListener(sensorEventListener);
}
}
This also did not solve my problem. So if someone knows how I can permanently register the TYPE_STEP_COUNTER sensor in my flutter app, please let me know.
Update:
I've contacted one of the developers of the pedometer package, and he suggested me to use flutter_foreground_service (which is developed by the same team/company as pedometer). It works.
But I would still find it interesting, if there is another way (maybe similar to my 2 failed attempts).
I have a file chooser button that triggers a change in the titlebar whenever a file is selected with it. And it seems to work fine in my non-flatpak build.
import gtk.Application : Application;
import gtk.ApplicationWindow : ApplicationWindow;
import gio.Application : GioApp = Application;
import gtkc.gtktypes : GApplicationFlags, FileChooserAction;
import gtk.FileChooserButton : FileChooserButton;
const string AppID = `org.github.flatfcbtest`;
int main(string[] args)
{
auto app = new App();
return app.run(args);
}
public class App : Application
{
public:
this(const string appID = AppID, const GApplicationFlags flags = GApplicationFlags.FLAGS_NONE)
{
super(appID, flags);
addOnActivate(delegate void(GioApp _) {
auto pw = new PrimaryWindow(this);
pw.showAll();
});
}
}
class PrimaryWindow : ApplicationWindow
{
this(Application app)
{
super(app);
setSizeRequest(500, 300);
auto fcb = new FileChooserButton(`Select file`, FileChooserAction.OPEN);
fcb.addOnFileSet(delegate void (FileChooserButton _) {
setTitle(`file set!`);
});
add(fcb);
}
}
(GtkD reference)
However in my flatpak builds, the file selected with the chooser button does not select anything and it keeps saying (None). However my titlebar is changes accordingly so I know that the signal was emitted by the file chooser button.
Here is my flatpak permissions list:
finish-args:
- --socket=fallback-x11
- --share=ipc
- --filesystem=host
- --device=all
- --socket=session-bus
What's causing this?
Typically if you're shipping a flatpak, you want to avoid --filesystem=host and just use GtkFileChooserNative instead. This class supports portals, allowing a user to select files the application does not have permission to access by itself.
This is a much better approach than giving the application full filesystem access. GtkFileChooserNative will still work in a non-flatpak application and you shouldn't notice any difference unless you're doing something fancy.
As for your question of why GtkFileChooser is not working with --filesystem=host however, I do not know.
Visual Studio Code Does Not Comment-out Empty Lines
I've searched everywhere for a solution to this issue but couldn't find anything, and it's been bugging me for months now.
Basically what happens is that VS Code ignores empty lines when you tell it to comment out multiple lines of code.
So for example, let's say I highlighted all the code below and told VS Code to comment it out:
package com.mycompany.app;
public class MyApp {
public static void main(String[] args) {
SayHello();
}
static void SayHello() {
System.out.println("Hello!");
}
}
What I expected to get:
// package com.mycompany.app;
//
// public class MyApp {
// public static void main(String[] args) {
// SayHello();
// }
//
// static void SayHello() {
// System.out.println("Hello!");
// }
// }
What I got instead:
// package com.mycompany.app;
// public class MyApp {
// public static void main(String[] args) {
// SayHello();
// }
// static void SayHello() {
// System.out.println("Hello!");
// }
// }
I've only experienced this with Java and Golang so far, but I assume this happens for all other languages inside VS Code too.
The reason I want my comments to stay connected to each other is so I know which lines I commented out together in case I need to uncomment them back.
I am also aware of the Shift + Alt + A shortcut, but that typically uses Block Comments (which I don't like using), and I only want Line Comments.
Is there a setting I'm missing? Because I tried searching within VS Code and couldn't find anything either.
Any help would be greatly appreciated.
An option to have empty lines commented out is coming to v1.48. See https://github.com/microsoft/vscode-docs/blob/vnext/release-notes/v1_48.md#thank-you and https://github.com/microsoft/vscode/pull/93160
New setting:
Editor > Comments: Ignore Empty Lines default is true (will ignore)
[editor.comments.includeEmptyLines]
In Insiders' Build already v1.48.
A new VS Code setting has been added that resolves this issue:
"editor.comments.ignoreEmptyLines": false
Unfortunately, it is only tagged as "insiders-released" despite being included in Stable versions of VS Code.
Hopefully, this issue gets addressed in future versions.
Multi-line Editing seems to be the only alternative solution so far.
Press and hold the Alt key and press either Up or Down so your cursor expands to multiple lines. Then just add // manually.
It isn't very intuitive, but it works. Hopefully, the VS Code team will address this issue someday.
UPDATE: This feature has now been added to the VS Code backlog! (https://github.com/microsoft/vscode/issues/88480)
I'm implementing a GUI application in Jython, using Eclipse and PyDev plugin.
The problem is that I have a hard time using the builtin debugger. When I start a debug session it just stops. Of course this should be expected as the program just creates a JFrame and then it's finished.
So any breakpoints I put for different events .e.g. pressing a button, will never happen as the debug session is already terminated.
What should I do ? I'm growing tired of using prints for all my debugging.
For instance, when I tried debugging this small Java example. I have no problem to hit
the breakpoint I had set in the windowClosing-method
import java.awt.event.*;
import javax.swing.*;
public class Test1 {
public static void main(String s[]) {
JFrame frame = new JFrame("JFrame Source Demo");
// Add a window listner for close button
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
frame.setVisible(true);
}
}
And then I tried this somewhat more or less similiar example in jython
from javax.swing import JFrame;
import java.awt.event.WindowListener as WindowListener
class Test1 (JFrame, WindowListener):
def __init__(self):
super(JFrame, self).__init__('Some name goes here', defaultCloseOperation = JFrame.EXIT_ON_CLOSE, size = (800, 800))
self.addWindowListener(self)
self.setVisible(True)
def windowClosing(self, windowEvent):
print 'window closing'
pass # want to hit this breakpoint
someFrame = Test1()
pass #breakpoint here maybe
If I tried to run the jython example in the debugger and it just terminates. Ok then I added a breakpoint after I created someFrame and a breakpoint in the windowClosing method. Still no luck, It doesn't get hit when I close the window but I see it executed as I see the printout.
Can anyone tell me what I'm doing wrong ? I'm sure I forgot something very simple.
Put a breakpoint in the first line of your main method that initiates the application.
If you want to debug certain actions like pressing a button add an action listener to a button and inside the handling method add the breakpoint. For example:
JButton button = new JButton("OK");
button.addActionListener(new ActionListener()
{
#Override
public void action(ActionEvent e)
{
System.out.println("button OK has been pressed"; // add breakpoint here
// call to some code that handles the event
}
});
I had the same problem
btnCompilar = new JButton("Compilar");
btnCompilar.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
compile(); //can't hit breakpoint here
}
});
I couldn't hit breakpoints inside actionPerformed, so I just made a method and used breakpoints in it.
void compile(){
//can hit breakpoint here
}