README.md

Ink

The Ink library is a freehand stroke generation library. It produces smoothed, modeled stroke shapes with brush effect shaders as mesh-based vector graphics.

This provides the core of the implementation of the Android Jetpack Ink library. While the implementation is well-tested, the developers of this library are not currently making hard guarantees about interface stability.

How to Build and Test

Bazel

Prerequisites:

• Bazel 7: https://bazel.build/install
• Android NDK: https://developer.android.com/ndk/downloads
  • Download and set ANDROID_NDK_HOME to point to it.
  • Alternately use sdkmanager or Android Studio: https://developer.android.com/studio/projects/install-ndk
• You may need to install libtinfo for clang
  • sudo apt-get install libtinfo5

Ink can be built and tested from the repo root:

bazel test --config=linux ink/...

Library Structure

Ink consists of a set of modules that can be used separately. You should only need to include the parts of the library that you need. The basic dependency structure is:

 ┌──────────┐ ┌───────┐
 │Rendering │ │Storage│
 └────┬─────┘ └──┬────┘
      │          │
      ▼          │
   ┌───────┐     │
   │Strokes│◄────┘
   └───┬───┘
       ▼
   ┌───────┐
   | Brush |
   └─┬────┬┘
     │    │
     │    ▼
     │ ┌────────┐
     │ │Geometry│
     │ └───┬────┘
     │     │
     ▼     ▼
 ┌─────┐ ┌─────┐
 │Color│ │Types│
 └─────┘ └─────┘

• color: Color spaces, encoding, and format conversion.
• types: Utility types; time, units, constants, small arrays.
• geometry: Geometric types (point, segment, triangle, rect, quad), meshes, transforms, utility functions, and algorithms (intersection, envelope).
• brush: Defines stroke styles and behaviors.
• strokes: The primary Stroke data type and InProgressStroke builder.
• rendering: Rendering utilities for strokes. Currently only has support for android.graphics.Mesh based rendering.
• storage: Protobuf serialization utilities for Stroke and related types.

Contributing

See CONTRIBUTING.md for details on sending a PR.

Contact

Use GitHub Issues to file feedback: https://github.com/google/ink/issues