Dasher for Windows

Dasher is an information-efficient text-entry interface, driven by continuous pointing gestures. It lets you write using eye gaze, a mouse, a switch, a joystick, or touch — designed for accessibility and augmentative communication (AAC).

This is the Windows frontend, built on the shared DasherCore engine.

dasher.at — downloads, user docs, and live demo Feature status — what each platform supports All repos — engine, frontends, design guide

Status

Preview — actively developed. Download the latest build from Releases. See the feature matrix for what's implemented.

Install

Download the latest MSI or portable ZIP from Releases. Run the installer or extract and run Dasher.Windows.exe.

Build

Prerequisites

• .NET 10 SDK
• CMake 3.20+
• Visual Studio 2026 Community (with C++ desktop development workload, CMake tools, and Windows SDK)
• Git (with submodules)

Steps

git clone --recurse-submodules https://github.com/dasher-project/Dasher-Windows.git
cd Dasher-Windows

1. Build the native DLL (from a Developer Command Prompt for VS):

cd native
.\build.ps1

Produces build/bin/dasher.dll. Copy it to the app directory:

copy .\build\bin\dasher.dll ..\src\Dasher.Windows\

2. Build and run the Avalonia app:

cd ..\src\Dasher.Windows
dotnet run

Architecture

DasherCore is a pure C++ engine. It computes the full zooming tree layout and renders through an abstract CDasherScreen interface. This frontend implements CDasherScreen inside the native DLL (via DasherCore's C API), serialising each draw call into a flat int[] command buffer. C# reads this buffer via P/Invoke and replays the draw calls into Avalonia's DrawingContext.

graph LR
    subgraph "DasherCore C++ DLL"
        A[CDasherScreen interface] --> B[CommandScreen<br/>serialises to int buffer]
    end
    subgraph "Avalonia C# App"
        B -->|P/Invoke<br/>int buffer| C[CommandRenderer.cs<br/>decodes ops]
        C --> D[DrawingContext<br/>Skia rendering]
        E[DasherCanvas.cs<br/>frame loop + pointer input] --> C
        E -->|dasher_frame| B
    end
    B -.->|dasher.dll| A

Loading

Each command is 6 ints: [opcode, a, b, c, d, argb]

Op	Meaning	Fields
0	Clear screen	argb = background colour
1	Circle	a=x, b=y, c=radius, d=1 filled / 0 outline
2	Line	a=x1, b=y1, c=x2, d=y2
3	Rectangle outline	a=x1, b=y1, c=x2, d=y2
4	Rectangle filled	a=x1, b=y1, c=x2, d=y2
5	Text	a=x, b=y, c=fontSize, d=stringIndex
6	Set line width	a=width

See DasherCore's C API for the engine contract.

Repository layout

Path	Purpose
DasherCore/	DasherCore submodule (do not edit here — PR upstream)
native/	CMake build glue: builds DasherCore CAPI into dasher.dll
src/Dasher.Windows/Engine/	P/Invoke bridge, command renderer, parameter keys
src/Dasher.Windows/Controls/	DasherCanvas (frame loop, input), SettingsPanel
src/Dasher.Windows/Views/	MainWindow (toolbars, canvas, message pane, settings overlay)
src/Dasher.Windows/Services/	Analytics, migration, speech, update checker
tests/Dasher.Windows.Tests/	xUnit tests (crash reporting, PII scrubbing)

Contributing

See CONTRIBUTING.md for build details, code style, and DCO sign-off. For project-wide conventions (code of conduct, RFCs, security), see the org contributing guide.

License

MIT — see LICENSE.