Torch App in Android using Jetpack Compose
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: