Jetpack compose: How to implement long press listener

Jetpack Compose - Long Press Listener

This code example demonstrates how to implement a long press listener in Jetpack Compose. It creates a text element that rotates when the user long presses on it.

Breakdown:

  1. Setting Up:

    • The code defines a MainActivity class that extends AppCompatActivity.
    • Inside onCreate, it sets the content using setContent with the MainContent composable.

  2. Main Content:

    • MainContent uses a Column to arrange its children vertically and centered.
    • It uses remember to create a mutable state variable isRotated to track the rotation state of the text.
    • animateFloatAsState animates the angle value based on the isRotated state, with a duration of 3 seconds and a specific easing function.

  3. Text with Long Press Detection:

    • A Text composable displays the text "Long Press Me".
    • The Modifier applies padding, rotates the text based on the angle animation, and uses pointerInput to capture user interactions.
    • Inside pointerInput, detectTapGestures is used to detect long presses.
    • When a long press is detected (onLongPress), the isRotated state is toggled, triggering the rotation animation.

  4. Preview:

    • The ComposablePreview function is for previewing the composable in the Android Studio toolset.
    • It's currently commented out, but you can uncomment MainContent to see the preview.

Summary

This example showcases a basic implementation of long press detection in Jetpack Compose. It utilizes state variables, animations, and the pointerInput modifier with detectTapGestures to achieve the desired functionality. This approach offers a clean and declarative way to handle long press interactions within your composables.


MainActivity.kt 

package com.cfsuman.jetpackcompose

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.activity.compose.setContent
import androidx.compose.animation.core.FastOutSlowInEasing
import androidx.compose.animation.core.animateFloatAsState
import androidx.compose.animation.core.tween
import androidx.compose.foundation.background
import androidx.compose.foundation.gestures.detectTapGestures
import androidx.compose.foundation.layout.*
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.rotate
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.input.pointer.pointerInput
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            MainContent()
        }
    }


    @Composable
    fun MainContent(){
        Column(
            modifier = Modifier
                .background(Color(0xFFEDEAE0))
                .fillMaxSize(),
            verticalArrangement = Arrangement.Center,
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            val isRotated = remember { mutableStateOf(false) }

            val angle: Float by animateFloatAsState(
                targetValue = if (isRotated.value) 360F else 0F,
                animationSpec = tween(
                    durationMillis = 3000, // duration
                    easing = FastOutSlowInEasing
                )
            )

            Text(
                text = "Long Press Me",
                fontSize = 50.sp,
                color = Color(0xFF7C0A02),
                modifier = Modifier
                    .padding(25.dp)
                    .rotate(angle)
                    .pointerInput(Unit) {
                        detectTapGestures(
                            onLongPress = {
                                isRotated.value = !isRotated.value
                            }
                        )
                    }
            )
        }
    }


    @Preview
    @Composable
    fun ComposablePreview(){
        //MainContent()
    }
}
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