tko-cactus · Oct 28, 2020
diff --git a/‎.github/ci-gradle.properties
+21-21 b/‎.github/ci-gradle.properties
+21-21
diff --git a/‎Crane/README.md
+34 b/‎Crane/README.md
+34
@@ -1,23 +1,23 @@
-/*
- * Copyright 2019 Google, Inc.
- *
- * 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
- *
- *     http://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.
- */
+#
+# Copyright 2020 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
+#
+#      http://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.
+#
 
- org.gradle.daemon=false
- org.gradle.parallel=true
- org.gradle.jvmargs=-Xmx5120m
- org.gradle.workers.max=2
+org.gradle.daemon=false
+org.gradle.parallel=true
+org.gradle.jvmargs=-Xmx5120m
+org.gradle.workers.max=2
 
- kotlin.incremental=false
- kotlin.compiler.execution.strategy=in-process
+kotlin.incremental=false
+kotlin.compiler.execution.strategy=in-process
@@ -32,6 +32,38 @@ implemented using a different Activity will be displayed. In there, you can see
 embedded in Compose and Compose buttons updating the Android View. Notice how you can also
 interact with the `MapView` seamlessly.
 
+## Hilt
+
+Crane uses [Hilt][hilt] to manage its dependencies. The Hilt's ViewModel extension (with the
+`@ViewModelInject` annotation) works perfectly with Compose's ViewModel integration (`viewModel()`
+composable function) as you can see in the following snippet of code. `viewModel()` will
+automatically use the factory that Hilt creates for the ViewModel:
+
+```
+class MainViewModel @ViewModelInject constructor(
+    private val destinationsRepository: DestinationsRepository,
+    @DefaultDispatcher private val defaultDispatcher: CoroutineDispatcher,
+    datesRepository: DatesRepository
+) : ViewModel() { ... }
+
+@Composable
+fun CraneHomeContent(...) {
+    val viewModel: MainViewModel = viewModel()
+    ...
+}
+```
+
+Disclaimer: Passing dependencies to a ViewModel which are not available at compile time (which is
+sometimes called _assisted injection_) doesn't work as you might expect using `viewModel()`.
+Compose's ViewModel integration cannot currently scope a ViewModel to a given composable. Instead
+it is always scoped to the host Activity or Fragment. This means that calling `viewModel()` with
+different factories in the same host Activity/Fragment don't have the desired effect; the _first_
+factory will be always used.
+
+This is the case of the [DetailsViewModel](detailsViewModel), which takes the name of
+a `City` as a parameter to load the required information for the screen. However, the above isn't a
+problem in this sample, since `DetailsScreen` is always used in it's own newly launched Activity.
+
 ## Google Maps SDK
 
 To get the MapView working, you need to get an API key as
@@ -79,6 +111,8 @@ limitations under the License.
 [details]: app/src/main/java/androidx/compose/samples/crane/details/DetailsActivity.kt
 [data]: app/src/main/java/androidx/compose/samples/crane/data/CraneData.kt
 [mainViewModel]: app/src/main/java/androidx/compose/samples/crane/home/MainViewModel.kt
+[detailsViewModel]: app/src/main/java/androidx/compose/samples/crane/details/DetailsViewModel.kt
 [homeTest]: app/src/androidTest/java/androidx/compose/samples/crane/home/HomeTest.kt
 [detailsTest]: app/src/androidTest/java/androidx/compose/samples/crane/details/DetailsActivityTest.kt
 [coil-accompanist]: https://github.com/chrisbanes/accompanist
+[hilt]: https://d.android.com/hilt