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2026-05-17 15:51:34 +00:00 · 2020-10-19 17:08:00 +03:00
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+# OS windows management
+
+## What is covered
+
+In this guide, we'll show you how to work with windows using Compose for Desktop.
+
+## Windows creation
+
+The main class for creating windows is AppWindow. The easiest way to create and launch a new window is to use an instance of the AppWindow class and call its method `show()`. You can see an example below:
+
+```kotlin
+import androidx.compose.desktop.AppWindow
+
+fun main() {
+    AppWindow().show {
+        // content
+    }
+}
+```
+
+There are two types of windows - modal and regular. Below are functions for creating each type of window:
+
+1. Window - regular window type.
+2. Dialog - modal window type. Such a window locks its parent window until the user completes working with it and closes the modal window.
+
+You can see an example for both types of windows below.
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.window.Dialog
+
+fun main() {
+    Window {
+        val dialogState = remember { mutableStateOf(false) }
+
+        Button(onClick = { dialogState.value = true }) {
+            Text(text = "Open dialog")
+        }
+
+        if (dialogState.value) {
+            Dialog(
+                onDismissEvent = { dialogState.value = false }
+            ) {
+                // dialog's content
+            }
+        }
+    }
+}
+```
+
+## Window attributes
+
+Each window has 9 parameters listed below, all of them could be omitted and have default values:
+
+1. title - window title
+2. size - initial window size
+3. location - initial window position
+4. centered - set the window to the center of the display
+5. icon - window icon
+6. menuBar - window context menu
+7. undecorated - disable native border and title bar of the window
+8. events - window events
+9. onDismissEvent - event when removing the window content from a composition
+
+An example of using window parameters at the creation step:
+
+```kotlin
+import androidx.compose.desktop.AppManager
+import androidx.compose.desktop.Window
+import androidx.compose.desktop.WindowEvents
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.input.key.Key
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.window.MenuItem
+import androidx.compose.ui.window.KeyStroke
+import androidx.compose.ui.window.Menu
+import androidx.compose.ui.window.MenuBar
+import java.awt.Color
+import java.awt.Graphics2D
+import java.awt.image.BufferedImage
+
+fun main() {
+    val count = mutableStateOf(0)
+    val windowPos = mutableStateOf(IntOffset.Zero)
+
+    Window(
+        title = "MyApp",
+        size = IntSize(400, 250),
+        location = IntOffset(100, 100),
+        centered = false, // true - by default
+        icon = getMyAppIcon(),
+        menuBar = MenuBar(
+            Menu(
+                name = "Actions",
+                MenuItem(
+                    name = "Increment value",
+                    onClick = {
+                        count.value++
+                    },
+                    shortcut = KeyStroke(Key.I)
+                ),
+                MenuItem(
+                    name = "Exit",
+                    onClick = { AppManager.exit() },
+                    shortcut = KeyStroke(Key.X)
+                )
+            )
+        ),
+        undecorated = true, // false - by default
+        events = WindowEvents(
+            onRelocate = { location ->
+                windowPos.value = location
+            }
+        )
+    ) {
+        // content
+        Box(
+            modifier = Modifier.fillMaxSize(),
+            alignment = Alignment.Center
+        ) {
+            Column {
+                Text(text = "Location: ${windowPos.value} Value: ${count.value}")
+                Button(
+                    onClick = {
+                        AppManager.exit()
+                    }
+                ) {
+                    Text(text = "Close app")
+                }
+            }
+        }
+    }
+}
+
+fun getMyAppIcon() : BufferedImage {
+    val size = 256
+    val image = BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB)
+    val graphics = image.createGraphics()
+    graphics.setColor(Color.orange)
+    graphics.fillOval(0, 0, size, size)
+    graphics.dispose()
+    return image
+}
+```
+
+![Window attributes](window_attr.gif)
+
+## Window properties
+
+AppWindow parameters correspond to the following properties:
+
+1. title - window title
+2. width - window width
+3. height - window height
+4. x - position of the left top corner of the window along the X axis
+5. y - position of the left top corner of the window along the Y axis
+6. icon - window icon image
+7. events - window events
+
+To get the properties of a window, it is enough to have a link to the current or specific window. There are two ways to get the current focused window:
+
+1. Using the global environment:
+
+```kotlin
+import androidx.compose.desktop.AppWindowAmbient
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.IntOffset
+
+fun main() {
+    val windowPos = mutableStateOf(IntOffset.Zero)
+    
+    Window {
+        val current = AppWindowAmbient.current
+        
+        // content
+        Box(
+            modifier = Modifier.fillMaxSize(),
+            alignment = Alignment.Center
+        ) {
+            Column {
+                Text(text = "Location: ${windowPos.value}")
+                Button(
+                    onClick = {
+                        if (current != null) {
+                            windowPos.value = IntOffset(current.x, current.y)
+                        }
+                    }
+                ) {
+                    Text(text = "Print window location")
+                }
+            }
+        }
+    }
+}
+```
+
+2. Using AppManager:
+
+```kotlin
+import androidx.compose.desktop.AppManager
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.IntOffset
+
+fun main() {
+    val windowPos = mutableStateOf(IntOffset.Zero)
+
+    Window {
+        // content
+        Box(
+            modifier = Modifier.fillMaxSize(),
+            alignment = Alignment.Center
+        ) {
+            Column {
+                Text(text = "Location: ${windowPos.value}")
+                Button(
+                    onClick = {
+                        val current = AppManager.focusedWindow
+                        if (current != null) {
+                            windowPos.value = IntOffset(current.x, current.y)
+                        }
+                    }
+                ) {
+                    Text(text = "Print window location")
+                }
+            }
+        }
+    }
+}
+```
+
+![Window properties](current_window.gif)
+
+Using the following methods, one can change the properties of AppWindow:
+
+1. setTitle(title: String) - window title
+2. setSize(width: Int, height: Int) - window size
+3. setLocation(x: Int, y: Int) - window position
+4. setWindowCentered() - set the window to the center of the display
+5. setIcon(image: BufferedImage?) - window icon
+
+```kotlin
+import androidx.compose.desktop.AppWindowAmbient
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.material.Button
+
+fun main() {
+    Window {
+        val current = AppWindowAmbient.current
+
+        // content
+        Button(
+            onClick = {
+                if (current != null) {
+                    current.setWindowCentered()
+                }
+            }
+        ) {
+            Text(text = "Center the window")
+        }
+    }
+}
+```
+
+![Window properties](center_the_window.gif)
+
+## Window events
+
+Events could be defined using the events parameter at the window creation step or redefine using the events property at runtime.
+Actions can be assigned to the following window events:
+
+1. onOpen - event during window opening
+2. onClose - event during window closing
+3. onMinimize - event during window minimizing
+4. onMaximize - event during window maximizing
+5. onRestore - event during restoring window size after window minimize/maximize
+6. onFocusGet - event when window gets focus
+7. onFocusLost - event when window loses focus
+8. onResize - event on window resize (argument is window size as IntSize)
+9. onRelocate - event of the window reposition on display (argument is window position as IntOffset)
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.desktop.WindowEvents
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.IntSize
+
+fun main() {
+    val windowSize = mutableStateOf(IntSize.Zero)
+    val focused = mutableStateOf(false)
+    
+    Window(
+        events = WindowEvents(
+            onFocusGet = { focused.value = true },
+            onFocusLost = { focused.value = false },
+            onResize = { size ->
+                windowSize.value = size
+            }
+        )
+    ) {
+        // content
+        Box(
+            modifier = Modifier.fillMaxSize(),
+            alignment = Alignment.Center
+        ) {
+            Text(text = "Size: ${windowSize.value} Focused: ${focused.value}")
+        }
+    }
+}
+```
+
+![Window events](focus_the_window.gif)
+
+## AppManager
+
+The AppManager singleton is used to customize the behavior of the entire application. Its main features:
+
+1. Description of common application events
+```kotlin
+AppManager.setEvents(
+    onAppStart = { println("onAppStart") }, // invoked before the first window is created
+    onAppExit = { println("onAppExit") } // invoked after all windows are closed
+)
+```
+2. Customization of common application context menu
+```kotlin
+AppManager.setMenu(
+    getCommonAppMenuBar() // custom function that returns MenuBar
+)
+```
+3. Access to the application windows list
+```kotlin
+val windows = AppManager.windows
+```
+4. Getting the current focused window
+```kotlin
+val current = AppManager.focusedWindow
+```
+5. Application exit
+```kotlin
+AppManager.exit() // closes all windows
+```
+
+## Access to Swing components
+
+Compose for Desktop is tightly integrated with Swing on the level of top level windows. For more detailed customization, you can access the JFrame (Swing window representation):
+
+```kotlin
+import androidx.compose.desktop.AppManager
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.Button
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+
+fun main() {
+    val scaleFactor = mutableStateOf(0.0)
+    Window {
+        // content
+        Box(
+            modifier = Modifier.fillMaxSize(),
+            alignment = Alignment.Center
+        ) {
+            Column {
+                Button(
+                    onClick = {
+                        val current = AppManager.focusedWindow
+                        if (current != null) {
+                            val jFrame = current.window
+                            // do whatever you want with it
+                            scaleFactor.value = jFrame.graphicsConfiguration.defaultTransform.scaleX
+                        }
+                    }
+                ) {
+                    Text(text = "Check display scaling factor")
+                }
+                Text(text = "Scaling factor: ${scaleFactor.value}}")
+            }
+        }
+    }
+}
+```
+
+![Access to Swing components](scaling_factor.jpg)