Pointer Modifier in Android using Jetpack Compose

Draggable Modifier in Android is the high-level entry point to drag gestures in a single orientation and reports the drag distance in pixels. The limitation of this modifier is that it is limited to a single orientation, i.e., the orientation can be either vertical or horizontal at a given point in time. So If we need to control the whole dragging gesture, i.e. multi-orientation, we must use the Pointer Modifier.

So in this article, we will show you how you could implement a Pointer Modifier in Android using Jetpack Compose. Follow the below steps once the IDE is ready.

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: 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.geeksforgeeks.jcpointerinputmodifier

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.background
import androidx.compose.foundation.gestures.detectDragGestures
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.input.pointer.consumeAllChanges
import androidx.compose.ui.input.pointer.pointerInput
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.dp
import kotlin.math.roundToInt

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

            // Creating a Simple Scaffold
            // Layout for the application
            Scaffold(

                // Creating a Top Bar
                topBar = { TopAppBar(title = { Text("GFG | Pointer Input Modifier", color = Color.White) }, backgroundColor = Color(0xff0f9d58)) },

                // Creating Content
                content = {

                    // Creating a Column Layout
                    Column(Modifier.fillMaxSize(), horizontalAlignment = Alignment.CenterHorizontally, verticalArrangement = Arrangement.Center) {

                        // Offset Values for X and Y
                        var offsetX by remember { mutableStateOf(0f) }
                        var offsetY by remember { mutableStateOf(0f) }

                        // Box Modifier Pointer
                        Box(
                            Modifier
                                .offset { IntOffset(offsetX.roundToInt(), offsetY.roundToInt()) }
                                .background(Color.Blue)
                                .size(50.dp)
                                .pointerInput(Unit) {
                                    detectDragGestures { change, dragAmount ->
                                        change.consumeAllChanges()
                                        offsetX += dragAmount.x
                                        offsetY += dragAmount.y
                                    }
                                }
                        )

                    }
                }
            )
        }
    }
}

Output:

You can see that we are able to implement the Pointer Modifier in our application.