[Ink API](https://developer.android.com/jetpack/androidx/releases/ink#1.0.0-alpha01) is modularized, so you can use only what you need.

## Strokes

The [strokes](https://developer.android.com/reference/kotlin/androidx/ink/strokes/package-summary) module serves as the foundation of the Ink API. Key data types
within this module are:

- [**`StrokeInputBatch`**](https://developer.android.com/reference/kotlin/androidx/ink/strokes/StrokeInputBatch): Represents a series of pointer inputs, including their position, timestamp, and optionally pressure, tilt, and orientation.
- [**`InProgressStroke`**](https://developer.android.com/reference/kotlin/androidx/ink/strokes/InProgressStroke): Represents a stroke that is actively being drawn. `InProgressStroke` is used to render partial strokes with low latency and to build the final `Stroke` once input is complete, after which the object can be reused. `InProgressStroke` is used by the [`InProgressStrokes`](https://developer.android.com/reference/kotlin/androidx/ink/authoring/compose/package-summary#InProgressStrokes(androidx.ink.brush.Brush,kotlin.Function0,androidx.compose.ui.graphics.Matrix,androidx.compose.ui.graphics.Matrix,androidx.compose.ui.graphics.Path,androidx.ink.brush.TextureBitmapStore,kotlin.Function1)) composable.
- [**`Stroke`**](https://developer.android.com/reference/kotlin/androidx/ink/strokes/Stroke): An immutable representation of a finalized stroke with fixed geometry. Each `Stroke` has an [`ImmutableStrokeInputBatch`](https://developer.android.com/reference/kotlin/androidx/ink/strokes/ImmutableStrokeInputBatch) (input points), a [`Brush`](https://developer.android.com/reference/kotlin/androidx/ink/brush/Brush) (style), and a [`PartitionedMesh`](https://developer.android.com/reference/kotlin/androidx/ink/geometry/PartitionedMesh) (geometric shape). You can store, manipulate, and render strokes within your application.

## Geometry

The [Geometry](https://developer.android.com/reference/kotlin/androidx/ink/geometry/package-summary) module supports geometric operations on primitive shapes (using
dedicated classes like [Box](https://developer.android.com/reference/kotlin/androidx/ink/geometry/Box&sa=D&source=docs&ust=1761326799140765&usg=AOvVaw1pQKRdqNKmIbX_E3mu9XBG) and [Vec](https://developer.android.com/reference/kotlin/androidx/ink/geometry/Vec)), as well as arbitrary shapes (using
[PartitionedMesh](https://developer.android.com/reference/kotlin/androidx/ink/geometry/PartitionedMesh)), including intersection detection and transformation.
[PartitionedMesh](https://developer.android.com/reference/kotlin/androidx/ink/geometry/PartitionedMesh) can also hold additional data to support rendering.

## Brush

The [`brush`](https://developer.android.com/reference/kotlin/androidx/ink/brush/Brush) module defines the style of strokes. It
consists of two main parts:

- [**`Brush`**](https://developer.android.com/reference/kotlin/androidx/ink/brush/Brush): Specifies the style of a stroke including base color, base size, and [`BrushFamily`](https://developer.android.com/reference/kotlin/androidx/ink/brush/BrushFamily). `BrushFamily` is analogous to a font family, it defines a stroke's style. For example, a `BrushFamily` can represent a specific style of marker or highlighter, allowing strokes with different sizes and colors to share that style.
- [**`StockBrushes`**](https://developer.android.com/reference/kotlin/androidx/ink/brush/StockBrushes): Provides factory functions for creating ready-to-use `BrushFamily` instances.

## Authoring

The Compose [Authoring](https://developer.android.com/reference/kotlin/androidx/ink/authoring/compose/package-summary) module lets you capture user touch input and render it
as low-latency strokes on the screen in real time. This is achieved through
the [`InProgressStrokes`](https://developer.android.com/reference/kotlin/androidx/ink/authoring/compose/package-summary#InProgressStrokes(androidx.ink.brush.Brush,kotlin.Function0,androidx.compose.ui.graphics.Matrix,androidx.compose.ui.graphics.Matrix,androidx.compose.ui.graphics.Path,androidx.ink.brush.TextureBitmapStore,kotlin.Function1)) composable, which processes motion events and displays
the strokes as they are drawn.

Once a stroke is completed, the composable notifies the client application using
an [`InProgressStrokesFinishedListener`](https://developer.android.com/reference/kotlin/androidx/ink/authoring/InProgressStrokesFinishedListener) callback. This allows the application
to retrieve the finished strokes for rendering or storage.

In Compose, `InProgressStrokes` takes this callback in the `onStrokesFinished`
parameter. Pass the finished strokes to another composable to commit them to the
screen using the [rendering module](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/canvas/package-summary).

## Rendering

The Rendering module simplifies drawing ink strokes onto an Android
[`Canvas`](https://developer.android.com/reference/kotlin/android/graphics/Canvas).
It provides [`CanvasStrokeRenderer`](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/canvas/CanvasStrokeRenderer) for Compose and
[`ViewStrokeRenderer`](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/view/ViewStrokeRenderer) for view-based layouts. These
renderers optimize rendering performance and help deliver high-quality visuals,
including antialiasing.

To render strokes, call the [`create()`](https://developer.android.com/reference/androidx/ink/rendering/android/canvas/CanvasStrokeRenderer#create(androidx.ink.brush.TextureBitmapStore)) method to get a
`CanvasStrokeRenderer` instance, and then call the [`draw()`](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/canvas/CanvasStrokeRenderer#draw(android.graphics.Canvas,androidx.ink.strokes.InProgressStroke,androidx.ink.geometry.AffineTransform)) method to
render either finished ([`Stroke`](https://developer.android.com/reference/kotlin/androidx/ink/strokes/Stroke)) or in-progress
([`InProgressStroke`](https://developer.android.com/reference/kotlin/androidx/ink/strokes/InProgressStroke)) strokes onto a `Canvas`.

You can transform the canvas when you draw a stroke. Examples include panning,
zooming, and rotating. To render the stroke correctly, you must also pass the
`canvas` transform to [`CanvasStrokeRenderer.draw`](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/canvas/CanvasStrokeRenderer#draw(android.graphics.Canvas,androidx.ink.strokes.InProgressStroke,androidx.ink.geometry.AffineTransform)).

To avoid tracking the `canvas` transform separately, use
[`ViewStrokeRenderer`](https://developer.android.com/reference/kotlin/androidx/ink/rendering/android/view/ViewStrokeRenderer) instead.

## Storage

The [storage](https://developer.android.com/reference/kotlin/androidx/ink/storage/package-summary) module provides utilities for
efficiently serializing and deserializing stroke data, primarily focusing
on [`StrokeInputBatch`](https://developer.android.com/reference/kotlin/androidx/ink/strokes/StrokeInputBatch).

The module uses [protocol buffers](https://protobuf.dev/) and optimized delta compression techniques,
resulting in significant storage savings compared to naive methods.

The storage module simplifies saving, loading, and sharing strokes.