feat: adds new snippet region tag for Desktop Windowing

compose/snippets/src/main/java/com/example/compose/snippets/adaptivelayouts/DesktopWindowing.kt

@@ -0,0 +1,163 @@
+/*
+ * Copyright 2026 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.compose.snippets.adaptivelayouts
+
+import android.app.Activity
+import android.app.PendingIntent
+import android.content.ClipData
+import android.content.ClipDescription
+import android.content.Intent
+import android.os.Bundle
+import android.view.View
+import android.view.WindowInsetsController
+import androidx.compose.foundation.background
+import androidx.compose.foundation.draganddrop.dragAndDropSource
+import androidx.compose.foundation.draganddrop.dragAndDropTarget
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.WindowInsets
+import androidx.compose.foundation.layout.captionBar
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.isCaptionBarVisible
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.windowInsetsTopHeight
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draganddrop.DragAndDropEvent
+import androidx.compose.ui.draganddrop.DragAndDropTarget
+import androidx.compose.ui.draganddrop.DragAndDropTransferData
+import androidx.compose.ui.draganddrop.toAndroidDragEvent
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.unit.dp
+import androidx.core.app.ActivityCompat.requestDragAndDropPermissions
+
+/**
+ * A custom Title Bar that respects the system caption bar insets.
+ */
+// [START android_compose_desktop_window_insets_title]
+@OptIn(ExperimentalLayoutApi::class)
+@Composable
+fun CaptionBar() {
+    if (WindowInsets.isCaptionBarVisible) {
+        Row(
+            modifier = Modifier
+                .windowInsetsTopHeight(WindowInsets.captionBar)
+                .fillMaxWidth()
+                .background(if (isSystemInDarkTheme()) Color.White else Color.Black),
+            horizontalArrangement = Arrangement.Center,
+            verticalAlignment = Alignment.CenterVertically
+        ) {
+            Text(
+                text = "Caption Bar Title",
+                style = MaterialTheme.typography.titleMedium,
+                modifier = Modifier.padding(4.dp)
+            )
+        }
+    }
+}
+// [END android_compose_desktop_window_insets_title]
+
+/**
+ * Transparent System Caption Bar
+ */
+class TransparentActionBarActivity : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        // [START android_compose_desktop_window_transparent_caption]
+        window.insetsController?.setSystemBarsAppearance(
+            WindowInsetsController.APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND,
+            WindowInsetsController.APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND
+        )
+        // [END android_compose_desktop_window_transparent_caption]
+    }
+}
+
+
+/**
+ * Simple drag source for plain text data.
+ */
+fun dragAndDropSourceModifier() {
+    // [START android_compose_desktop_drag_drop_source]
+    Modifier.dragAndDropSource { _ ->
+        DragAndDropTransferData(
+            clipData = ClipData.newPlainText("label", "Your data"),
+            flags = View.DRAG_FLAG_GLOBAL_SAME_APPLICATION
+        )
+    }
+    // [END android_compose_desktop_drag_drop_source]
+}
+
+/**
+ * Custom drag source that launches a new Activity instance when dropped.
+ */
+fun customDragAndDropSource(activity: Activity, itemId: String) {
+    // [START android_compose_desktop_drag_drop_source_unhandled_flag]
+    Modifier.dragAndDropSource { _ ->
+        val intent = Intent.makeMainActivity(activity.componentName).apply {
+            putExtra("EXTRA_ITEM_ID", itemId)
+            flags = Intent.FLAG_ACTIVITY_NEW_TASK or
+                    Intent.FLAG_ACTIVITY_MULTIPLE_TASK or
+                    Intent.FLAG_ACTIVITY_LAUNCH_ADJACENT
+        }
+
+        val pendingIntent = PendingIntent.getActivity(
+            activity, 0, intent, PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val data = ClipData(
+            "Item $itemId",
+            arrayOf(ClipDescription.MIMETYPE_TEXT_INTENT),
+            ClipData.Item.Builder().setIntentSender(pendingIntent.intentSender).build()
+        )
+
+        DragAndDropTransferData(
+            clipData = data,
+            flags = View.DRAG_FLAG_GLOBAL_SAME_APPLICATION or
+                    View.DRAG_FLAG_START_INTENT_SENDER_ON_UNHANDLED_DRAG,
+        )
+    }
+    // [END android_compose_desktop_drag_drop_source_unhandled_flag]
+}
+
+/**
+ * A target modifier configured to receive plain text drag events.
+ */
+fun dragAndDropTargetModifier(activity: Activity) {
+    // [START android_compose_desktop_drag_drop_target]
+    Modifier.dragAndDropTarget(
+        shouldStartDragAndDrop = { event ->
+            event.toAndroidDragEvent().clipDescription.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN)
+        },
+        target = object : DragAndDropTarget {
+            override fun onDrop(event: DragAndDropEvent): Boolean {
+                requestDragAndDropPermissions(activity, event.toAndroidDragEvent())
+                val clipData = event.toAndroidDragEvent().clipData
+                val item = clipData?.getItemAt(0)?.text
+                if (item != null) {
+                    // Process the dropped text item here
+                }
+                return item != null
+            }
+        }
+    )
+    // [END android_compose_desktop_drag_drop_target]
+}