swift-ui-autograph

Swift Package providing a view for capturing a users signature/autograph using drag gestures. It is named autograph to avoid confusion with the overloaded word signature 😀

Usage

It accepts a Binding to list of strokes represented as [[CGPoint]] for storing the strokes. The points are in normalized form allowing for projection onto arbitrary canvas sizes.

For example if using a SwiftData backed model

@Model
class AutographCard {
    var strokes: [[CGPoint]]
}

A View can be constructed consisting of

    import SwiftData
    @Query private var autographs: [AutoGraphCard]

    var body: some View {
        
    ...
        if let autograph = autographs.first {
            Autograph($autograph.strokes)
        }
    ...
    }

You can capture the size of the canvas the autograph is being written on in realtime. Do this by providing a Binding<CGSize> to the intializers canvasSize parameter.

Output

The package provides a simple SVG encoder as an extension to [[CGPoint]]. This can be used by calling svg(strokeWidth:strokeColor:on:) providing a CGSize for the aspect ratio.

var body: some View {
...
  Autograph($autograph.strokes)
              
  Button("Print") {
      print("SVG output is: \n\(autograph.strokes.svg(on: CGSize(width: 2, height: 1)) ?? "nil")")
  }
...
}

Dependencies

It has a dependency to my utility package SwiftUIHelpers for tracking the canvas size, as well as the SwiftDocCPlugin for generating documentation.

Rendering in SwiftUI

To display the autograph in a view you can use the provided AutographShape implementation of Shape, or use the path(in:) extension directly to create more advanced shapes.

ObservableObject (Pre SwiftData) usage

Since the view accepts the type Binding<[[CGPoint]] any Published reference of that type can be used by accesing its binding with the $ operator.

Documentation

The latest documentation is hosted here

See also

The Demo Project included in this package has usage examples based on a SwiftData model scheme, showing how to create and display autographs.