signature Flutter Plugin

You can customize the app's launch screen by replacing the existing image files in the example/ios/Runner/Assets.xcassets/LaunchImage.imageset/ directory with your own assets.

Alternatively, you can manage these assets using Xcode:

1. Open the iOS workspace using open ios/Runner.xcworkspace.
2. In the Xcode Project Navigator, select Runner/Assets.xcassets.
3. Locate the LaunchImage asset set and drag and drop your desired images into it.

To use the signature plugin in your Flutter project, add it as a dependency in your pubspec.yaml file.

dependencies:
  signature: ^6.4.0

In version 5.0.0 and later, the Signature widget no longer automatically wraps itself in an Expanded widget when dimensions are not specified. This change prevents Incorrect use of ParentDataWidget errors.

How to handle layout changes:

• If you provide width and height: No changes are required.
• If you are using the widget inside a Row, Column, or Flex without dimensions: You must now manually wrap the Signature widget in an Expanded widget.
• If you are using the widget without dimensions outside of Flex widgets: No changes are required.

A signature is composed of a list of Point objects. Each Point represents a specific interaction on the canvas.

• Point: Contains the offset (2D coordinates), the pressure applied (if supported), and the type of movement.
• PointType: An enum defining how the point was created:
  • PointType.tap: A single touch at a specific location (used for start/end of strokes).
  • PointType.move: A finger moving across the display.

You can access the raw list of points via controller.points or controller.value.

The SignatureController manages an internal undo/redo system based on discrete actions (strokes).

1. Capturing State: Every time a user finishes a stroke (onPointerUp or onPointerCancel), the controller calls pushCurrentStateToUndoStack(). This saves the current list of points into _latestActions.
2. Undo: Calling undo() removes the last action from _latestActions and moves it to _revertedActions. The canvas is then updated to the state before that action.
3. Redo: Calling redo() takes the last action from _revertedActions, moves it back to _latestActions, and applies it to the canvas.
4. Clearing: Calling clear() wipes all points and resets both the undo and redo stacks.

The Signature widget provides a canvas for users to draw signatures. It requires a SignatureController to manage the drawing state and interaction. You can optionally specify dimensions (width, height), a backgroundColor, and a placeholder widget to show when the canvas is empty.

By default, the widget expands to fill its parent container unless width or height are provided.

```dart
final SignatureController controller = SignatureController(
  penColor: Colors.black,
  penStrokeWidth: 3.0,
);

// In your widget tree:
Signature(
  controller: controller,
  backgroundColor: Colors.grey,
  placeholder: Text('Please sign here'),
)```

You can save a signature's state by exporting its points and later re-initializing a new SignatureController using those points. This allows you to load previously saved signatures.

// 1. Export points from an existing controller
var exportedPoints = _controller.points;

// 2. Initialize a new controller with those points to restore the state
final SignatureController _restoredController = SignatureController(points: exportedPoints);

The Signature widget is the UI component that renders the canvas. It requires a SignatureController and can be configured with specific dimensions and a background color.

var _signatureCanvas = Signature(
  controller: _controller,
  width: 300,
  height: 300,
  backgroundColor: Colors.lightBlueAccent,
);

The SignatureController allows you to customize the visual appearance of the signature lines using standard Flutter Paint properties:

• penColor: The color of the signature line.
• penStrokeWidth: The thickness of the line.
• strokeCap: The shape of the line ends (e.g., StrokeCap.butt, StrokeCap.round).
• strokeJoin: The shape of the line joins (e.g., StrokeJoin.miter, StrokeJoin.round).

final controller = SignatureController(
  penColor: Colors.red,
  penStrokeWidth: 5.0,
  strokeCap: StrokeCap.round,
  strokeJoin: StrokeJoin.round,
);

The controller provides two ways to export the signature as SVG:

1. toRawSVG({int? width, int? height, double minDistanceBetweenPoints = 3}): Returns a String? containing the raw <svg> XML. This is useful for server-side processing or custom rendering.
2. toSVG({int? width, int? height, double minDistanceBetweenPoints = 3}): Returns an SvgPicture? (from the flutter_svg package) ready to be displayed in a Flutter widget tree.

The minDistanceBetweenPoints parameter helps reduce the SVG file size by optimizing the number of points included in the path.

// Displaying the signature as an SVG widget
SvgPicture? svgWidget = controller.toSVG(width: 300, height: 100);

if (svgWidget != null) {
  return svgWidget;
}