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Torch App in Android using Jetpack Compose

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Nowadays almost all mobile devices come with a flashlight that is used by the camera. Along with that, this same flashlight is also used as a torch on android devices. For using this flashlight there are many android applications named Torch to use this flashlight as a torch. In this article, we will be creating a simple torch application in android using Jetpack Compose.

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. While choosing the template, select Empty Compose Activity. If you do not find this template, try upgrading the Android Studio to the latest version. We demonstrated the application in Kotlin, so make sure you select Kotlin as the primary language while creating a New Project.

Step 2: Adding a new color to the Color.kt file

Navigate to app > java > your app’s package name > ui.theme > Color.kt file and add the below code to it.

Kotlin




package com.example.newcanaryproject.ui.theme
 
import androidx.compose.ui.graphics.Color
 
val Purple200 = Color(0xFF0F9D58)
val Purple500 = Color(0xFF0F9D58)
val Purple700 = Color(0xFF3700B3)
val Teal200 = Color(0xFF03DAC5)
 
// on below line we are adding different colors.
val greenColor = Color(0xFF0F9D58)


Step 3: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin




package com.example.newcanaryproject
 
import android.app.Activity
import android.content.Context
import android.content.pm.ActivityInfo
import android.hardware.camera2.CameraManager
import android.net.ConnectivityManager
import android.os.Build
import android.os.Bundle
import android.provider.Settings.*
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.annotation.RequiresApi
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.core.content.ContextCompat.getSystemService
import com.example.newcanaryproject.ui.theme.NewCanaryProjectTheme
import com.example.newcanaryproject.ui.theme.greenColor
 
class MainActivity : ComponentActivity() {
 
    @RequiresApi(Build.VERSION_CODES.M)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            NewCanaryProjectTheme {
                // on below line we are specifying
                // background color for our application
                Surface(
                    // on below line we are specifying
                    // modifier and color for our app
                    modifier = Modifier.fillMaxSize(), color = MaterialTheme.colors.background
                ) {
 
                    // on the below line we are specifying
                    // the theme as the scaffold.
                    Scaffold(
 
                        // in scaffold we are specifying the top bar.
                        topBar = {
 
                            // inside top bar we are specifying
                            // background color.
                            TopAppBar(backgroundColor = greenColor,
 
                                // along with that we are specifying
                                // title for our top bar.
                                title = {
 
                                    // in the top bar we are specifying
                                    // title as a text
                                    Text(
                                        // on below line we are specifying
                                        // text to display in top app bar.
                                        text = "GFG",
 
                                        // on below line we are specifying
                                        // modifier to fill max width.
                                        modifier = Modifier.fillMaxWidth(),
 
                                        // on below line we are specifying
                                        // text alignment.
                                        textAlign = TextAlign.Center,
 
                                        // on below line we are specifying
                                        // color for our text.
                                        color = Color.White
                                    )
                                })
                        }) {
                        // on below line we are calling our
                        // method to display UI
                        torchApplication(LocalContext.current)
                    }
                }
            }
        }
    }
}
 
@Composable
fun torchApplication(context: Context) {
    val torchStatus = remember {
        mutableStateOf(false)
    }
    val torchMsg = remember {
        mutableStateOf("Off")
    }
    // on below line we are creating a column,
    Column(
        // on below line we are adding
        // a modifier to it,
        modifier = Modifier
            .fillMaxSize()
            // on below line we are adding a padding.
            .padding(all = 30.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
    ) {
        // on below line we are creating a text
        // for displaying torch status.
        Text(
            text = "Torch is " + torchMsg.value,
            // on below line we are
            // displaying a text color
            color = Color.Black,
 
            // on below line we are
            // setting font weight
            fontWeight = FontWeight.Bold,
 
            // on below line we are setting
            // font family
            fontFamily = FontFamily.Default,
 
            // on below line we are setting
            // font size and padding.
            fontSize = 20.sp, modifier = Modifier.padding(5.dp)
        )
 
        // on below line creating a switch for displaying a torch
        Switch(checked = torchStatus.value, onCheckedChange = {
            torchStatus.value = it
            // on below line we are creating
            // a variable for camera manager.
            lateinit var cameraManager: CameraManager
 
            // one below line we are
            // creating a string for camera ID
            lateinit var cameraID: String
 
            // on below line we are initializing our camera manager.
            cameraManager = context.getSystemService(Context.CAMERA_SERVICE) as CameraManager
            try {
                // O means back camera unit,
                // 1 means front camera unit
                // on below line we are getting camera id
                // for back camera as we will be using
                // torch for back camera
                cameraID = cameraManager.cameraIdList[0]
            } catch (e: Exception) {
                // on below line we are handling exception.
                e.printStackTrace()
            }
 
            if (torchStatus.value) {
                try {
                    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
                        // if button is checked we are simply
                        // initializing our camera manager and
                        // setting torch mode for back camera
                        // as true to switch on torch
                        cameraManager.setTorchMode(cameraID, true)
 
                        // on below line we are simply displaying
                        // a toast message for torch on.
                        Toast.makeText(context, "Torch turned on..", Toast.LENGTH_LONG)
                            .show()
 
                        // on below line we are setting text
                        // to our text view as torch on.
                        torchMsg.value = "On"
                    }
                } catch (e: Exception) {
                    // on below line we are handling exception.
                    e.printStackTrace()
                }
            } else {
                // this condition will be called
                // when switch is off.
                try {
                    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
                        // if button is unchecked this method will be called.
                        // In this method we will initializing our camera
                        // manager with camera id and setting torch to off.
                        cameraManager.setTorchMode(cameraID, false)
 
                        // on below line we are simply displaying a toast message.
                        Toast.makeText(context, "Torch turned off..", Toast.LENGTH_SHORT)
                            .show()
 
                        // on below line we are
                        // setting text to text view.
                        torchMsg.value = "Off"
                    }
                    // on below line we are
                      // handling exception
                } catch (e: Exception) {
                    e.printStackTrace()
                }
            }
        })
    }
}


Now run your application to see the output of it. 

Output:



Last Updated : 28 Sep, 2022
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