Keyboard tutorial

tutorials/Keyboard/main.md

@@ -0,0 +1,119 @@
+# Keyboard events handling
+
+## Prerequisites
+
+This tutorial expects set and ready Compose project build similar to which is described in [Getting Started tutorial](../Getting_Started)
+
+## KeySets & ShortcutHandler
+
+Compose for Desktop has a few utilities to work with shortcuts:
+
+`KeysSet` represents a simultaneously pressed chord of keys. You can construct a `KeysSet` using Key's extension function:
+
+``` kotlin
+Key.CtrlLeft + Key.Enter
+```
+
+`ShortcutHandler` accepts `KeysSet` and returns a handler which could be used as a callback for `keyInputFilter`
+
+## Event handlers
+
+There are two different ways how you can handle key events in Compose for Desktop:
+
+- By setting up an event handler based on a focused component
+- By setting up an event handler in the scope of the window
+
+## Focus related events
+
+It's working in the same way as in Compose for Android, see for details [API Reference](https://developer.android.com/reference/kotlin/androidx/compose/ui/input/key/package-summary#keyinputfilter)
+
+The most common use case is to define keyboard handlers for active controls like `TextField`. Here is an example:
+
+``` kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.TextField
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.key.*
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.dp
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.setValue
+
+@OptIn(ExperimentalKeyInput::class)
+fun main() = Window(title = "Compose for Desktop", size = IntSize(300, 300)) {
+    MaterialTheme {
+        var consumedText by remember { mutableStateOf(0) }
+        var text by remember { mutableStateOf("") }
+        Column(Modifier.fillMaxSize(), Arrangement.spacedBy(5.dp)) {
+            Text("Consumed text: $consumedText")
+            TextField(
+                    value = text,
+                    onValueChange = { text = it },
+                    modifier = Modifier.keyInputFilter(
+                            ShortcutHandler(Key.CtrlLeft + Key.Enter) {
+                                consumedText += text.length
+                                text = ""
+                            }
+                    )
+            )
+        }
+    }
+}
+```
+
+
+Note an annotation `@OptIn(ExperimentalKeyInput::class)`. Keyboard-related event handlers are a still-experimental feature of Compose and API changes are possible, so it requires it to use special annotation to emphasize the experimental nature of the code.
+
+![keyInputFilter](keyInputFilter.gif)
+
+## Window-scoped events
+
+`AppWindow` instances have `keyboard` property. Using it, it's possible to define keyboard shortcuts that are always active for the current window. See an example:
+
+``` kotlin
+import androidx.compose.desktop.AppWindow
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Text
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.Button
+import androidx.compose.material.MaterialTheme
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.key.ExperimentalKeyInput
+import androidx.compose.ui.input.key.Key
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.dp
+
+@OptIn(ExperimentalKeyInput::class)
+fun main() = Window(title = "Compose for Desktop", size = IntSize(300, 300)) {
+    MaterialTheme {
+        Column(Modifier.fillMaxSize(), Arrangement.spacedBy(5.dp)) {
+            Button(
+                    modifier = Modifier.padding(4.dp),
+                    onClick = {
+                        AppWindow(size = IntSize(200, 200)).also {
+                            it.keyboard.shortcut(Key.Escape) {
+                                it.close()
+                            }
+                        }.show {
+                            Text("I'm popup!")
+                        }
+                    }
+            ) {
+                Text("Open popup")
+            }
+        }
+    }
+}
+```
+
+![window_keyboard](window_keyboard.gif)