| Go on Android |
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| GothamGo |
| 15 Nov 2014 |
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| David Crawshaw |
| Google |
| @davidcrawshaw |
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| * Video |
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| This talk was presented at GothamGo in New York City, November 2014. |
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| .link http://vimeo.com/115307069 Watch the talk on Vimeo |
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| * Go on Mobile |
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| The goal is to bring Go to Android and iOS, |
| starting with Android. |
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| This is new territory for Go and a well-established |
| ecosystem. A lot of experimentation is necessary. |
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| * Today |
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| * Go 1.4 Status |
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| The coming 1.4 release can build binaries for Android OS. |
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| With the `mobile` subrepository and the Android SDK/NDK, it can: |
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| - Build `.so` files for linking into Android Apps |
| - Build apps based on NativeActivity ("All Go") |
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| * What's there |
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| - Go standard library tests running on Android OS |
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| - JDK / runtime hooks |
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| - The `gobind` tool, for calling Go from Java: [[http://golang.org/s/gobind]] |
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| Packages for cross-device apps: |
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| - [[https://godoc.org/golang.org/x/mobile/app][App control]] |
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| - [[https://godoc.org/golang.org/x/mobile/gl][OpenGL ES 2]] |
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| - [[https://godoc.org/golang.org/x/mobile/event][Touch events]] |
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| - [[https://godoc.org/golang.org/x/mobile/geom][Screen geometry]] |
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| * What's missing — a good build system |
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| There's more than one way to build an Android App. |
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| None of them |
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| - fit well with what go programmers expect (the go tool) |
| - work for cross-device development |
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| We are working on this for Go 1.5. |
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| Until it is done, using Go on Android requires some bravery. |
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| * What it's for — the two kinds of apps |
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| *SDK* *Apps* |
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| Write your Android UI in Java. |
| Write your iOS UI in Objective-C/Swift. |
| Write your logic in Go. |
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| Share the Go using interfaces generated by `gobind`. |
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| *NDK* *Apps* |
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| Games. |
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| Use OpenGL or the coming 2D [[http://godoc.org/golang.org/x/mobile/sprite][sprite]] package to write to the screen. |
| Everything is written in Go. |
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| * Hello, World! |
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| Portable APIs, just Go. This is a complete app: |
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| .play gothamgo-android/red.go |
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| * Write anywhere |
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| Developing with portable APIs means starting from very little. |
| It is a lot of work to get going and limits access to device features. |
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| But it also frees us from device-specific build systems. |
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| The app package includes Mac/X11 shims for starting as normal programs. |
| We can write Apps anywhere we can write Go. |
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| (Windows coming soon.) |
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| * Touch events |
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| .play gothamgo-android/touch.go |
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| * Package sprite |
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| We are building a 2D rendering and compositing package. |
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| It renders a scene graph. A scene starts with a root |
| `*sprite.Node`, which can have child nodes. |
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| Each node may have an affine transform and texture. |
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| Rendering is done in a depth-first traversal of the scene, |
| with transforms applied relative to the parent. |
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| Composition is done in OpenGL. |
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| * Sprite — affine transform |
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| .image gothamgo-android/sprite_affine.svg |
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| * Sprite — depth first traversal, applying parent's transforms |
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| .image gothamgo-android/sprite_subtex.svg |
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| * Sprite Demo |
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| * Sprite — what's next |
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| - Rasterizer, CPU-based for now |
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| - Text, based on freetype-go |
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| - Simple UI elements, focused on game menu needs |
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| - Debugging tools |
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| - Performance |
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| * Go 1.5 Plans (July 2015) |
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| - A build system |
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| - OpenAL bindings for sound |
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| - Very basic UI building blocks for game-like apps |
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| - iOS experimental support |
