# Context Menu in Compose for Desktop

## What is covered

In this tutorial we will cover all aspects of work with Context Menu
using the Compose UI framework.

## Default context menu 
There is out-of-the box context menu support for TextField and Selectable text. 

To enable standard context menu for a TextField you just need to put it inside DesktopMaterialTheme:

```kotlin
import androidx.compose.material.Text
import androidx.compose.material.TextField
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.window.singleWindowApplication

fun main() = singleWindowApplication(title = "Context menu") {
    val text = remember { mutableStateOf("Hello!") }
    TextField(
        value = text.value,
        onValueChange = { text.value = it },
        label = { Text(text = "Input") }
    )
}
```
<img width="396" alt="image" src="https://user-images.githubusercontent.com/5963351/190021028-c207164d-df04-4294-ad8f-da3106c16fb6.png">


Standard context menu for TextField contains the following items based on text selection: Copy, Cut, Paste, Select All.

Enabling standard context menu for a Text component is similar - you just need to make it selectable: 

```kotlin
import androidx.compose.foundation.text.selection.SelectionContainer
import androidx.compose.material.Text
import androidx.compose.ui.window.singleWindowApplication

fun main() = singleWindowApplication(title = "Context menu") {
    SelectionContainer {
        Text("Hello World!")
    }
}
```
Context menu for text contains just Copy action:

<img width="391" alt="image" src="https://user-images.githubusercontent.com/5963351/190020951-0cc539a2-f698-4e2b-bc20-9d4aa1b11c6f.png">

## User-defined context menu
To enable additional context menu items for TextField and Text components, ContextMenuDataProvider and ContextMenuItem elements are used:

```kotlin
import androidx.compose.foundation.ContextMenuDataProvider
import androidx.compose.foundation.ContextMenuItem
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.text.selection.SelectionContainer
import androidx.compose.material.Text
import androidx.compose.material.TextField
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.compose.ui.window.singleWindowApplication

fun main() = singleWindowApplication(title = "Context menu") {
    val text = remember { mutableStateOf("Hello!") }
    Column {
        ContextMenuDataProvider(
            items = {
                listOf(
                    ContextMenuItem("User-defined Action") {/*do something here*/ },
                    ContextMenuItem("Another user-defined action") {/*do something else*/ }
                )
            }
        ) {
            TextField(
                value = text.value,
                onValueChange = { text.value = it },
                label = { Text(text = "Input") }
            )

            Spacer(Modifier.height(16.dp))

            SelectionContainer {
                Text("Hello World!")
            }
        }
    }
}
```
In this example Text/TextField context menus will be extended with two additional items:

<img width="430" alt="image" src="https://user-images.githubusercontent.com/5963351/190020831-9b87b191-a351-4f70-a726-d5a53577ad53.png">

## Context menu for an arbitrary area
There is a possibility to create a context menu for an arbitrary application window area. This is implemented using ContextMenuArea API that is 
similar to ContextMenuDataProvider. 
```kotlin
import androidx.compose.foundation.ContextMenuArea
import androidx.compose.foundation.ContextMenuItem
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.width
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import androidx.compose.ui.window.singleWindowApplication

fun main() = singleWindowApplication(title = "Context menu") {
    ContextMenuArea(items = {
        listOf(
            ContextMenuItem("User-defined Action") {/*do something here*/},
            ContextMenuItem("Another user-defined action") {/*do something else*/}
        )
    }) {
        Box(modifier = Modifier.background(Color.Blue).height(100.dp).width(100.dp))
    }
}
```
Right click on the Blue Square will show a context menu with two items:

<img width="423" alt="image" src="https://user-images.githubusercontent.com/5963351/190020592-15e851f8-e356-413c-b5c3-225393712292.png">

## Styling context menu
Style of context menu doesn't comply MaterialTheme. To change its colors, you should override `LocalContextMenuRepresentation`:
```kotlin
import androidx.compose.foundation.DarkDefaultContextMenuRepresentation
import androidx.compose.foundation.LightDefaultContextMenuRepresentation
import androidx.compose.foundation.LocalContextMenuRepresentation
import androidx.compose.foundation.isSystemInDarkTheme
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.TextField
import androidx.compose.material.darkColors
import androidx.compose.material.lightColors
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.window.singleWindowApplication

fun main() = singleWindowApplication {
    isSystemInDarkTheme()
    MaterialTheme(
        colors = if (isSystemInDarkTheme()) darkColors() else lightColors()
    ) {
        val contextMenuRepresentation = if (isSystemInDarkTheme()) {
            DarkDefaultContextMenuRepresentation
        } else {
            LightDefaultContextMenuRepresentation
        }
        CompositionLocalProvider(LocalContextMenuRepresentation provides contextMenuRepresentation) {
            Surface(Modifier.fillMaxSize()) {
                Box {
                    var value by remember { mutableStateOf("") }
                    TextField(value, { value = it })
                }
            }
        }
    }
}
```
<img width="392" alt="image" src="https://user-images.githubusercontent.com/5963351/190514663-d345a0ba-0b4c-4920-b6cd-743a753d7d83.png">

## Custom text context menu
You can override text menu for all texts and text fields in your application, overriding `TextContextMenu`:
```kotlin
import androidx.compose.foundation.ContextMenuDataProvider
import androidx.compose.foundation.ContextMenuItem
import androidx.compose.foundation.ContextMenuState
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.text.LocalTextContextMenu
import androidx.compose.foundation.text.TextContextMenu
import androidx.compose.foundation.text.selection.SelectionContainer
import androidx.compose.material.Text
import androidx.compose.material.TextField
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.awt.ComposePanel
import androidx.compose.ui.platform.LocalUriHandler
import androidx.compose.ui.text.AnnotatedString
import java.awt.Dimension
import java.net.URLEncoder
import java.nio.charset.Charset
import javax.swing.JFrame
import javax.swing.SwingUtilities

fun main() = SwingUtilities.invokeLater {
    val panel = ComposePanel()
    panel.setContent {
        CustomTextMenuProvider {
            Column {
                SelectionContainer {
                    Text("Hello, Compose!")
                }

                var text by remember { mutableStateOf("") }

                TextField(text, { text = it })
            }
        }
    }

    val window = JFrame()
    window.contentPane.add(panel)
    window.size = Dimension(800, 600)
    window.isVisible = true
}

@OptIn(ExperimentalFoundationApi::class)
@Composable
fun CustomTextMenuProvider(content: @Composable () -> Unit) {
    val textMenu = LocalTextContextMenu.current
    val uriHandler = LocalUriHandler.current
    CompositionLocalProvider(
        LocalTextContextMenu provides object : TextContextMenu {
            @Composable
            override fun Area(
                textManager: TextContextMenu.TextManager,
                state: ContextMenuState,
                content: @Composable () -> Unit
            ) {
                // Here we reuse the original TextContextMenu, but add an additional item to item on the bottom.
                ContextMenuDataProvider({
                    val shortText = textManager.selectedText.crop()
                    if (shortText.isNotEmpty()) {
                        val encoded = URLEncoder.encode(shortText, Charset.defaultCharset())
                        listOf(ContextMenuItem("Search $shortText") {
                            uriHandler.openUri("https://google.com/search?q=$encoded")
                        })
                    } else {
                        emptyList()
                    }
                }) {
                    textMenu.Area(textManager, state, content = content)
                }
            }
        },
        content = content
    )
}

private fun AnnotatedString.crop() = if (length <= 5) toString() else "${take(5)}..."
```
<img width="453" alt="image" src="https://user-images.githubusercontent.com/5963351/190509388-92cff018-2880-4cfe-95c4-4c023ecac09d.png">

## Swing interoperability
If you are embedding Compose into an existing application, you may want the text context menu to look the same as in other parts of the application. To do this, there is `JPopupTextMenu`:
```kotlin
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.text.JPopupTextMenu
import androidx.compose.foundation.text.LocalTextContextMenu
import androidx.compose.foundation.text.selection.SelectionContainer
import androidx.compose.material.Text
import androidx.compose.material.TextField
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.awt.ComposePanel
import androidx.compose.ui.platform.LocalLocalization
import java.awt.Color
import java.awt.Component
import java.awt.Dimension
import java.awt.Graphics
import java.awt.event.KeyEvent
import java.awt.event.KeyEvent.CTRL_DOWN_MASK
import java.awt.event.KeyEvent.META_DOWN_MASK
import javax.swing.Icon
import javax.swing.JFrame
import javax.swing.JMenuItem
import javax.swing.JPopupMenu
import javax.swing.KeyStroke.getKeyStroke
import javax.swing.SwingUtilities
import org.jetbrains.skiko.hostOs

fun main() = SwingUtilities.invokeLater {
    val panel = ComposePanel()
    panel.setContent {
        JPopupTextMenuProvider(panel) {
            Column {
                SelectionContainer {
                    Text("Hello, Compose!")
                }

                var text by remember { mutableStateOf("") }

                TextField(text, { text = it })
            }
        }
    }

    val window = JFrame()
    window.contentPane.add(panel)
    window.size = Dimension(800, 600)
    window.isVisible = true
}

@OptIn(ExperimentalFoundationApi::class)
@Composable
fun JPopupTextMenuProvider(owner: Component, content: @Composable () -> Unit) {
    val localization = LocalLocalization.current
    CompositionLocalProvider(
        LocalTextContextMenu provides JPopupTextMenu(owner) { textManager, items ->
            JPopupMenu().apply {
                textManager.cut?.also {
                    add(
                        swingItem(localization.cut, Color.RED, KeyEvent.VK_X, it)
                    )
                }
                textManager.copy?.also {
                    add(
                        swingItem(localization.copy, Color.GREEN, KeyEvent.VK_C, it)
                    )
                }
                textManager.paste?.also {
                    add(
                        swingItem(localization.paste, Color.BLUE, KeyEvent.VK_V, it)
                    )
                }
                textManager.selectAll?.also {
                    add(JPopupMenu.Separator())
                    add(
                       swingItem(localization.selectAll, Color.BLACK, KeyEvent.VK_A, it)
                    )
                }
                
                // Here we add other items that can be defined additionaly in the other places of the application via ContextMenuDataProvider
                for (item in items) {
                    add(
                        JMenuItem(item.label).apply {
                            addActionListener { item.onClick() }
                        }
                    )
                }
            }
        },
        content = content
    )
}

private fun swingItem(
    label: String,
    color: Color,
    key: Int,
    onClick: () -> Unit
) = JMenuItem(label).apply {
    icon = circleIcon(color)
    accelerator = getKeyStroke(key, if (hostOs.isMacOS) META_DOWN_MASK else CTRL_DOWN_MASK)
    addActionListener { onClick() }
}

private fun circleIcon(color: Color) = object : Icon {
    override fun paintIcon(c: Component?, g: Graphics, x: Int, y: Int) {
        g.create().apply {
            this.color = color
            translate(16, 2)
            fillOval(0, 0, 16, 16)
        }
    }

    override fun getIconWidth() = 16

    override fun getIconHeight() = 16
}
```
<img width="448" alt="image" src="https://user-images.githubusercontent.com/5963351/191312702-f455ab2c-4c47-4e11-b615-fc67af1af3f9.png">