Add Glance in-app widget pinning snippet (#580)

Add Glance in-app widget pinning snippet

Author: ashnohe

compose/snippets/src/main/java/com/example/compose/snippets/glance/GlancePinAppWidget.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2025 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.glance
+
+import android.content.Context
+import androidx.compose.material3.Button
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import androidx.glance.GlanceId
+import androidx.glance.appwidget.GlanceAppWidget
+import androidx.glance.appwidget.GlanceAppWidgetManager
+import androidx.glance.appwidget.GlanceAppWidgetReceiver
+import kotlinx.coroutines.launch
+
+class MyWidgetReceiver : GlanceAppWidgetReceiver() {
+    override val glanceAppWidget: GlanceAppWidget = MyWidget()
+}
+
+class MyWidget : GlanceAppWidget() {
+    override suspend fun provideGlance(
+        context: Context,
+        id: GlanceId
+    ) {}
+}
+
+// [START android_compose_glance_in_app_pinning]
+@Composable
+fun AnInAppComposable() {
+    val context = LocalContext.current
+    val coroutineScope = rememberCoroutineScope()
+    Button(
+        onClick = {
+            coroutineScope.launch {
+                GlanceAppWidgetManager(context).requestPinGlanceAppWidget(
+                    receiver = MyWidgetReceiver::class.java,
+                    preview = MyWidget(),
+                    previewState = DpSize(245.dp, 115.dp)
+                )
+            }
+        }
+    ) {}
+}
+// [END android_compose_glance_in_app_pinning]