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| 1 Contributing | |
| 2 ============ | |
| 3 | |
| 4 [sky_sdk](https://github.com/domokit/sky_sdk) is generated from the | |
| 5 [mojo repository](https://github.com/domokit/mojo) using | |
| 6 [deploy_sdk.py](https://github.com/domokit/mojo/blob/master/sky/tools/deploy_sdk
.py) | |
| 7 Static files (including this README.md) are located under | |
| 8 [sky/sdk](https://github.com/domokit/mojo/tree/master/sky/sdk). Pull | |
| 9 requests and issue reports are glady accepted at the | |
| 10 [mojo repository](https://github.com/domokit/mojo)! | |
| 11 | |
| 12 Sky | |
| 13 === | |
| 14 | |
| 15 Sky is an experimental, high-performance UI framework for mobile apps. Sky helps | |
| 16 you create apps with beautiful user interfaces and high-quality interactive | |
| 17 design that run smoothly at 120 Hz. | |
| 18 | |
| 19 Sky consists of two components: | |
| 20 | |
| 21 1. *The Sky engine.* The engine is the core of the system. Written in C++, the | |
| 22 engine provides the muscle of the Sky system. The engine provides | |
| 23 several primitives, including a soft real-time scheduler and a hierarchical, | |
| 24 retained-mode graphics system, that let you build high-quality apps. | |
| 25 | |
| 26 2. *The Sky framework.* The [framework](packages/sky/lib/framework) makes it | |
| 27 easy to build apps using Sky by providing familiar user interface widgets, | |
| 28 such as buttons, infinite lists, and animations, on top of the engine using | |
| 29 Dart. These extensible components follow a functional programming style | |
| 30 inspired by [React](http://facebook.github.io/react/). | |
| 31 | |
| 32 We're still iterating on Sky heavily, which means the framework and underlying | |
| 33 engine are both likely to change in incompatible ways several times, but if | |
| 34 you're interested in trying out the system, this document can help you get | |
| 35 started. | |
| 36 | |
| 37 Examples | |
| 38 -------- | |
| 39 | |
| 40 Sky uses Dart and Sky applications are | |
| 41 [Dart Packages](https://www.dartlang.org/docs/tutorials/shared-pkgs/). | |
| 42 Application creation starts by creating a new directory and | |
| 43 adding a [pubspec.yaml](https://www.dartlang.org/tools/pub/pubspec.html): | |
| 44 | |
| 45 pubspec.yaml for your app: | |
| 46 ```yaml | |
| 47 name: your_app_name | |
| 48 dependencies: | |
| 49 sky: any | |
| 50 ``` | |
| 51 | |
| 52 Once the pubspec is in place, create a `lib` directory (where your dart code | |
| 53 will go), ensure that the 'dart' and 'pub' executables are on your $PATH and | |
| 54 run the following: | |
| 55 | |
| 56 `pub get && pub run sky:init`. | |
| 57 | |
| 58 Currently the Sky Engine assumes the entry point for your application is a | |
| 59 `main` function located inside a `main.sky` file at the root of the package. | |
| 60 `.sky` is an html-like format: | |
| 61 ``` | |
| 62 <sky> | |
| 63 <script> | |
| 64 import 'package:your_app_name/main.dart'; | |
| 65 | |
| 66 void main() { | |
| 67 new HelloWorldApp(); | |
| 68 } | |
| 69 </script> | |
| 70 </sky> | |
| 71 ``` | |
| 72 | |
| 73 The rest of the application then goes inside the `lib` directory of the package | |
| 74 thus `lib/main.dart` would be: | |
| 75 | |
| 76 ```dart | |
| 77 import 'package:sky/framework/fn.dart'; | |
| 78 | |
| 79 class HelloWorldApp extends App { | |
| 80 UINode build() { | |
| 81 return new Text('Hello, world!'); | |
| 82 } | |
| 83 } | |
| 84 ``` | |
| 85 | |
| 86 Execution starts in `main`, which creates the `HelloWorldApp`. The framework | |
| 87 then marks `HelloWorldApp` as dirty, which schedules it to build during the next | |
| 88 animation frame. Each animation frame, the framework calls `build` on all the | |
| 89 dirty components and diffs the virtual `UINode` hierarchy returned this frame | |
| 90 with the hierarchy returned last frame. Any differences are then applied as | |
| 91 mutations to the physical hierarchy retained by the engine. | |
| 92 | |
| 93 Skip down to "Running a Sky application" to learn how to load and run this | |
| 94 example on your device. | |
| 95 | |
| 96 For examples, please see the [examples directory](examples/). | |
| 97 | |
| 98 Services | |
| 99 -------- | |
| 100 | |
| 101 Sky apps can access services from the host operating system using Mojo IPC. For | |
| 102 example, you can access the network using the `network_service.mojom` interface. | |
| 103 Although you can use these low-level interfaces directly, you might prefer to | |
| 104 access these services via libraries in the framework. For example, the | |
| 105 `fetch.dart` library wraps the underlying `network_service.mojom` in an | |
| 106 ergonomic interface: | |
| 107 | |
| 108 ```dart | |
| 109 import 'package:sky/framework/net/fetch.dart'; | |
| 110 | |
| 111 main() async { | |
| 112 Response response = await fetch('example.txt'); | |
| 113 print(response.bodyAsString()); | |
| 114 } | |
| 115 ``` | |
| 116 | |
| 117 Set up your computer | |
| 118 -------------------- | |
| 119 | |
| 120 1. Install the Dart SDK: | |
| 121 - https://www.dartlang.org/tools/download.html | |
| 122 | |
| 123 2. Install the ``adb`` tool from the Android SDK: | |
| 124 - https://developer.android.com/sdk/installing/index.html | |
| 125 | |
| 126 3. Install the Sky SDK: | |
| 127 - ``git clone https://github.com/domokit/sky_sdk.git`` | |
| 128 | |
| 129 4. Ensure that $DART_SDK is set to the path of your Dart SDK and 'adb' | |
| 130 (inside 'platform-tools' in the android sdk) is in your $PATH. | |
| 131 | |
| 132 Set up your device | |
| 133 ------------------ | |
| 134 | |
| 135 Currently Sky requires an Android device running the Lollipop (or newer) version | |
| 136 of the Android operating system. | |
| 137 | |
| 138 1. Enable developer mode on your device by visiting ``Settings > About phone`` | |
| 139 and tapping the ``Build number`` field five times. | |
| 140 | |
| 141 2. Enable ``USB debugging`` in ``Settings > Developer options``. | |
| 142 | |
| 143 3. Using a USB cable, plug your phone into your computer. If prompted on your | |
| 144 device, authorize your computer to access your device. | |
| 145 | |
| 146 Running a Sky application | |
| 147 ------------------------- | |
| 148 | |
| 149 The `sky` pub package includes a `sky_tool` script to assist in running | |
| 150 Sky applications inside the `SkyDemo.apk` harness. The sky_tool script expects | |
| 151 to be run from the root directory of your application pub package. To run | |
| 152 one of the examples in this SDK, try: | |
| 153 | |
| 154 1. ``cd examples/stocks`` | |
| 155 | |
| 156 2. ``pub get`` to set up a copy of the sky package in the app directory. | |
| 157 | |
| 158 3. ``./packages/sky/sky_tool start`` to start the dev server and upload your | |
| 159 app to the device. | |
| 160 (NOTE: add a ``--install`` flag to install SkyDemo.apk if not already | |
| 161 installed on the device.) | |
| 162 | |
| 163 4. Use ``adb logcat`` to view any errors or Dart print() output from the app. | |
| 164 ``adb logcat -s chromium`` can be used to filter only adb messages from | |
| 165 `SkyDemo.apk` (which for | |
| 166 [legacy reasons](https://github.com/domokit/mojo/issues/129) still uses the | |
| 167 android log tag 'chromium'). | |
| 168 | |
| 169 Measuring Performance | |
| 170 --------------------- | |
| 171 | |
| 172 Sky has support for generating trace files compatible with | |
| 173 [Chrome's about:tracing](https://www.chromium.org/developers/how-tos/trace-event
-profiling-tool). | |
| 174 | |
| 175 `packages/sky/sky_tool start_tracing` and `packages/sky/sky_tool stop_tracing` | |
| 176 are the commands to use. | |
| 177 | |
| 178 Due to https://github.com/domokit/mojo/issues/127 tracing currently | |
| 179 requires root access on the device. | |
| 180 | |
| 181 Debugging | |
| 182 --------- | |
| 183 | |
| 184 Dart's [Observatory](https://www.dartlang.org/tools/observatory/) | |
| 185 (VM Debugger & Profiler) support in Sky is | |
| 186 [in progress](https://codereview.chromium.org/1107803002) and should | |
| 187 be released shortly after Dart Summit 2015. | |
| 188 | |
| 189 Building a standalone MyApp | |
| 190 --------------------------- | |
| 191 | |
| 192 Although it is possible to bundle the Sky Engine in your own app (instead of | |
| 193 running your code inside SkyDemo.apk), right now doing so is difficult. | |
| 194 | |
| 195 There is one example of doing so if you're feeling brave: | |
| 196 https://github.com/domokit/mojo/tree/master/sky/apk/stocks | |
| 197 | |
| 198 Eventually we plan to make this much easier and support platforms other than | |
| 199 Android, but that work is yet in progress. | |
| 200 | |
| 201 Adding Services to MyApp | |
| 202 ------------------------ | |
| 203 | |
| 204 [Mojo IPC](https://github.com/domokit/mojo) is an inter-process-communication | |
| 205 system designed to provide cross-thread, cross-process, and language-agnostic | |
| 206 communication between applications. Sky uses Mojo IPC to make it possible | |
| 207 to write UI code in Dart and yet depend on networking code, etc. written in | |
| 208 another language. Services are replicable, meaning that Dart code | |
| 209 written to use the `network_service` remains portable to any platform | |
| 210 (iOS, Android, etc.) by simply providing a 'natively' written `network_service`. | |
| 211 | |
| 212 Embedders of the Sky Engine and consumers of the Sky Framework can use this | |
| 213 same mechanism to expose not only existing services like the | |
| 214 [Keyboard](https://github.com/domokit/mojo/blob/master/mojo/services/keyboard/pu
blic/interfaces/keyboard.mojom) | |
| 215 service to allow Sky Framework Dart code to interface with the underlying | |
| 216 platform's Keyboard, but also to expose any additional non-Dart business logic | |
| 217 to Sky/Dart UI code. | |
| 218 | |
| 219 As and example, [SkyApplication](https://github.com/domokit/mojo/blob/master/sky
/shell/org/domokit/sky/shell/SkyApplication.java) | |
| 220 exposes a mojo `network_service` (required by Sky Engine C++ code) | |
| 221 [SkyDemoApplication](https://github.com/domokit/mojo/blob/master/sky/apk/demo/or
g/domokit/sky/demo/SkyDemoApplication.java) | |
| 222 additionally exposes `keyboard_service` and `sensor_service` for use by the Sky | |
| 223 Framework from Dart. | |
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