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.w3wiki.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.