# Getting Started with Compose for Desktop
## What is covered
In this tutorial we will see how to install mouse event listeners on components
in Compose for Desktop.
## Mouse event listeners
### Click listeners
Click listeners are available in both Compose on Android and Compose for Desktop,
so code like this will work on both platforms:
```kotlin
import androidx.compose.desktop.Window
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.combinedClickable
import androidx.compose.foundation.layout.*
import androidx.compose.material.Text
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.unit.IntSize
import androidx.compose.ui.unit.sp
fun main() = Window(title = "Compose for Desktop", size = IntSize(400, 400)) {
var count = remember { mutableStateOf(0) }
Box(contentAlignment = Alignment.Center, modifier = Modifier.fillMaxWidth()) {
var text = remember { mutableStateOf("Click magenta box!") }
Column {
@OptIn (ExperimentalFoundationApi::class)
Box(
modifier = Modifier
.background(Color.Magenta)
.fillMaxWidth(0.7f)
.fillMaxHeight(0.2f)
.combinedClickable(
onClick = {
text.value = "Click! ${count.value++}"
},
onDoubleClick = {
text.value = "Double click! ${count.value++}"
},
onLongClick = {
text.value = "Long click! ${count.value++}"
}
)
)
Text(text = text.value, fontSize = 40.sp)
}
}
}
```
### Mouse move listeners
As typically mouse and other positional pointers are only available on desktop platforms,
the following code will only work with Compose for Desktop.
Let's create a window and install a pointer move filter on it that changes the background
color according to the mouse pointer position:
```kotlin
import androidx.compose.desktop.Window
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
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.input.pointer.pointerMoveFilter
import androidx.compose.ui.unit.IntSize
fun main() = Window(title = "Compose for Desktop", size = IntSize(400, 400)) {
var color = remember { mutableStateOf(Color(0, 0, 0)) }
Box(
modifier = Modifier
.wrapContentSize(Alignment.Center)
.fillMaxSize()
.background(color = color.value)
.pointerMoveFilter(
onMove = {
color.value = Color(it.x.toInt() % 256, it.y.toInt() % 256, 0)
false
}
)
)
}
```
### Mouse enter listeners
Compose for Desktop also supports pointer enter and exit handlers, like this:
```kotlin
import androidx.compose.desktop.Window
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.material.Text
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.input.pointer.pointerMoveFilter
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.unit.IntSize
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
fun main() = Window(title = "Compose for Desktop", size = IntSize(400, 400)) {
Column(verticalArrangement = Arrangement.spacedBy(10.dp)) {
repeat(10) { index ->
var active = remember { mutableStateOf(false) }
Text(
modifier = Modifier
.fillMaxWidth()
.background(color = if (active.value) Color.Green else Color.White)
.pointerMoveFilter(
onEnter = {
active.value = true
false
},
onExit = {
active.value = false
false
}
),
fontSize = 30.sp,
fontStyle = if (active.value) FontStyle.Italic else FontStyle.Normal,
text = "Item $index"
)
}
}
}
```
### Mouse right/middle clicks and keyboard modifiers
While first-class support for pointer type-specific data, like pressed mouse buttons, is still in development in Compose, there is an available raw AWT mouse event object in Compose for Desktop, that can be used as a workaround when you need advanced functionality.
```kotlin
import androidx.compose.desktop.Window
import androidx.compose.foundation.gestures.forEachGesture
import androidx.compose.foundation.layout.Column
import androidx.compose.material.Text
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.getValue
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.input.pointer.AwaitPointerEventScope
import androidx.compose.ui.input.pointer.PointerEvent
import androidx.compose.ui.input.pointer.changedToDown
import androidx.compose.ui.input.pointer.consumeDownChange
import androidx.compose.ui.input.pointer.pointerInput
import androidx.compose.ui.unit.IntSize
import java.awt.event.MouseEvent
fun main() = Window(title = "Compose for Desktop", size = IntSize(400, 400)) {
var lastEvent by remember { mutableStateOf< MouseEvent ? > (null) }
Column {
Text(
text = "Custom button",
modifier = Modifier.pointerInput(Unit) {
forEachGesture {
awaitPointerEventScope {
lastEvent = awaitEventFirstDown().also {
it.changes.forEach { it.consumeDownChange() }
}.mouseEvent
}
}
}
)
Text("Mouse event: ${lastEvent?.paramString()}")
}
}
private suspend fun AwaitPointerEventScope.awaitEventFirstDown(): PointerEvent {
var event: PointerEvent
do {
event = awaitPointerEvent()
} while (
!event.changes.all { it.changedToDown() }
)
return event
}
```
