Milestro

Milestro is a native Skia text rendering stack for Unity.

The project bypasses Unity's built-in text rendering path and lets Unity call a native C++ layer for paragraph layout, glyph processing, rasterization, Unicode utilities, and render-target output.

Milestro is still a proof-of-concept. The APIs and Unity component surfaces are usable, but the repository is organized for active development rather than as a finished UPM package.

What It Provides

• A native C++ library built around Skia, SkParagraph, SkSVG, and ICU.
• A C-compatible game/plugin API in include/Milestro/game/milestro_game_interface.h.
• Generated Unity C# bindings in apps/unity-plugins/Milestro/Binding/BindingC.cs.
• An iOS framework/static-link bridge in apps/unity-plugins/Milestro/Plugins/iOS/FrameworkBinding.cpp.
• Managed Unity wrappers for Skia canvas, images, paths, SVG, fonts, text layout, render textures, and Unicode helpers.
• Unity components for UI text, world-space text, and editable text input.
• Rich text parsing helpers for a small XML-like tag set.
• Native Unity render-event integration for selected graphics backends.

Unity Installation

The Unity assets live under apps/unity-plugins/. Treat this directory as the contents of a Unity Assets/ folder, or copy/link the directories you need into your project.

Before importing Milestro, add the external ParaParty packages to the Unity project's Packages/manifest.json:

{
  "dependencies": {
    "party.para.util.colors": "https://github.com/ParaParty/ParaPartyUtil.git?path=Colors",
    "party.para.util.unitynative": "https://github.com/ParaParty/ParaPartyUtil.git?path=UnityNative"
  }
}

These are required by Milestro.asmdef: party.para.util.colors is used by the rich text color parser, and party.para.util.unitynative is used by managed native-object wrappers and native callback helpers.

If a consuming Unity project defines MILEASE_HAS_NEWTONSOFT and provides Newtonsoft.Json, Milestro model DTOs include optional JsonProperty metadata. Newtonsoft remains optional and is not required by default.

Runtime assets needed by the current code:

• Native plugin binary named for DllImport("libMilestro") on non-iOS targets.
• iOS builds use DllImport("__Internal") with the FrameworkBinding entry-point prefix.
• ICU data copied to Assets/Resources/Milestro/icudtl.dat.bytes. In this repo the source data is ext/icu-cmake/common/icudtl.dat, and the Unity target path maps to apps/unity-plugins/Resources/Milestro/icudtl.dat.bytes.

See docs/unity.md for the full Unity integration notes.

Main Unity APIs

Stable component entry points:

• Milestro.Components.TextBox: UI Graphic that renders text into a render texture through Skia.
• Milestro.Components.WorldSpaceTextBox: world-space quad presenter backed by the same text render-target pipeline.
• Milestro.Components.TextInput: editable UI text input backed by the native InputBox text model.

Lower-level managed wrappers:

• Milestro.Skia: canvas, image, font registry, typeface, path, SVG, vertex data, Unity render texture surfaces, and render command lists.
• Milestro.Skia.TextLayout: paragraph style, text style, strut style, paragraph builder, paragraph, font collection, and input box wrappers.
• Milestro.Unicode: ICU loading, normalization, segmentation, transliteration, case mapping, and collation helpers.
• Milestro.RichTextParser: markup parsing into paragraph payloads.

apps/unity-plugins/Milestro.Experimental/ contains older experimental bitmap, mesh, and SDF text components. Keep it optional unless you are working on those paths directly.

Native Architecture

Milestro is split into a native layer and a Unity layer.

Native layer:

• src/skia/ and include/Milestro/skia/: C++ wrappers for Skia canvas, images, fonts, typefaces, paths, SVG, vertex data, and text layout.
• src/skia/unicode/: Skia Unicode bridge code.
• src/unicode/ and include/Milestro/unicode/: ICU-backed Unicode helpers.
• src/io/ and include/Milestro/io/: native IO helpers.
• src/game/ and include/Milestro/game/: exported plugin API used by Unity.
• src/unity_render/: Unity native render-event integration.

Unity layer:

• apps/unity-plugins/Milestro/Binding/: generated C# P/Invoke bindings.
• apps/unity-plugins/Milestro/Skia/: managed Skia and render-target wrappers.
• apps/unity-plugins/Milestro/Skia/TextLayout/: managed paragraph and input-box APIs.
• apps/unity-plugins/Milestro/Unicode/: managed ICU and Unicode helpers.
• apps/unity-plugins/Milestro/Components/: Unity components.
• apps/unity-plugins/Milestro/RichTextParser/: XML-like rich text parsing.
• apps/unity-plugins/Milestro.Editor/: editor menu utilities.

Build And Tooling

Milestro uses CMake for native code and Gradle for C header to C# binding generation.

Skia is not vendored in this repository. Build Skia separately and pass either its library output directory or its CMake directory to Milestro:

cmake -S . -B cmake-build-relwithdebinfo -G Ninja \
  -DCMAKE_BUILD_TYPE=RelWithDebInfo \
  -DMILESTRO_SKIA_LIB_PATH=/path/to/skia/out/build \
  -DMILESTRO_SKIA_INCLUDE_PATH=/path/to/skia

cmake --build cmake-build-relwithdebinfo --target Milestro

Useful targets:

• Milestro: native shared or static library.
• MilestroCli: optional CLI target, enabled by default.
• H2CS: regenerates Unity binding files from the public C++ API.
• Native tests under tests/, enabled by default with MILESTRO_ENABLE_TESTS=ON.

Regenerate bindings after changing include/Milestro/game/milestro_game_interface.h:

./gradlew h2cs

Format C# Unity sources:

./gradlew format

See docs/build.md for CMake options, test commands, and the current Windows build flow.

Render Backend Status

The render-target path is platform-dependent:

• Apple builds compile the Metal backend.
• Windows builds compile the Direct3D 12 backend.
• Android enables OpenGLES3 and Vulkan backends when the platform libraries are found.
• Desktop OpenGL and desktop Vulkan are experimental CMake options: MILESTRO_ENABLE_DESKTOP_OPENGL_RENDER and MILESTRO_ENABLE_DESKTOP_VULKAN_RENDER.

UnityAutoRenderTextureSurface currently auto-selects Metal, Direct3D 12, OpenGLES3, or OpenGLCore from Unity's active graphics device. MSAA render targets are not supported yet.

Repository Layout

apps/
  cmd/                  Native CLI entry point
  unity-plugins/        Unity C# plugin code and Unity resources
cmake/                  CMake helper modules
docs/                   Project documentation
ext/                    Vendored third-party dependencies except Skia
include/Milestro/       Public native headers
scripts/                Release and symbol-management scripts
src/                    Native implementation
tests/                  Native tests and test data