SwipeType

SwipeType is a small .NET library for turning swipe paths into word suggestions. It works in regular .NET projects and in Unity projects that support netstandard2.0.

Use:

• QwertySwipeType for tolerant English QWERTY swipe ranking.
• MatchSwipeType for strict ordered path matching.
• DistanceSwipeType as a simple edit-distance fallback.

Example

using System.Collections.Generic;
using System.IO;
using SwipeType;

var swipeType = new QwertySwipeType(File.ReadAllLines("wordlist.txt"));
string swipePath = "heqerqllo";

foreach (string suggestion in swipeType.GetSuggestion(swipePath, 2))
{
    Console.WriteLine(suggestion);
    // Output:
    // hello
    // hero
}

If you have word frequencies, pass them to improve ranking:

var frequencies = new Dictionary<string, double>
{
    ["hello"] = 1000,
    ["hero"] = 50
};
var swipeType = new QwertySwipeType(File.ReadAllLines("wordlist.txt"), frequencies);

Frequencies are especially useful with large dictionaries and noisy swipe paths, where several uncommon words can match the same keyboard geometry.

Algorithm notes

The original idea is based on Krishna Bharadwaj's swype.py gist: a word is a candidate when its letters appear in the swipe path in order, with endpoint and minimum-length filters to keep the candidate set small.

MatchSwipeType keeps that strict path-matching behavior. QwertySwipeType adds QWERTY keyboard geometry, nearby endpoint matching, dynamic path-to-word alignment, bounded top-N ranking, and optional word-frequency boosts.

This is a deterministic swipe-ranking library, not a full keyboard language model. With large dictionaries and noisy paths, several rare words can be geometrically valid matches, so passing word frequencies is recommended for production-quality ranking.

Unity

SwipeType targets netstandard2.0, so it can be used as a managed plug-in in Unity projects that use the .NET Standard API compatibility level.

Recommended setup:

1. Build SwipeType in Release configuration.
2. Copy SwipeType/bin/Release/netstandard2.0/SwipeType.dll into your Unity project's Assets/Plugins folder.
3. Keep Unity's Player Settings > Other Settings > Api Compatibility Level on .NET Standard unless your project has a specific reason to use .NET Framework.

You can also copy the source files from SwipeType/ directly into a Unity project. The library doesn't use dynamic code generation, reflection emit, unsafe code, or platform-specific APIs.

License

SwipeType is licensed under the Apache-2.0 License.