pencil_field 0.0.2

Pencil Input

FLUTTER PENCIL FIELD

pencil_field 0.0.2

Widget for pencil / stylus input on different devices and platforms. This widget is intended for any freehand input like signatures or drawings. The widget also supports full persistence of the input. It can either be accessed as JSON (to keep it editable) or as image (e.g., for archiving or immutability reasons).

How to use

The PencilField can be embedded in any screen (in this case in a StatefulWidget):

PencilField(
  controller: widget.controller,
  pencilPaint: pencilPaint,
  onPencilDrawingChanged: widget.onPencilDrawingChanged,
  decoration: PencilDecoration(
    type: PencilDecorationType.chequered,
    backgroundColor: Colors.white,
    patternColor: Colors.grey[300]!,
    numberOfLines: 10,
    lineWidth: 2,
    padding: const EdgeInsets.all(10),
  ),
  pencilOnly: true,
)

And resulting input can be displayed like so (also embedded in a StatefulWidget). As everything is stored in vector format scaling (e.g. for creating previews) is easy:

PencilDisplay(
  pencilDrawing: widget.controller.drawing.scale(
    scale: scale,
  ),
  decoration: PencilDecoration(backgroundColor: Colors.white),
)

Features

PencilField

Name	Type	Default	Description
key	Key?		Assign key to PencilField widget
controller	PencilController	Always required	Controller to interact with the widget during user input
pencilPaint	PencilPaint	Always required	The paint that will be used for the current interaction
decoration	PencilDecoration?	Blank decoration	Style of the background (see below)
onPencilDrawingChanged	OnPencilDrawingChanged?		Callback when the content of the drawing changes
pencilOnly	bool	false	If set to true only input from pen devices is used

PencilFieldDecoration

Name	Type	Default	Description
type	PencilDeorationType	blank	Type of decoration. It can either be blank, chequered, lines, dots. Examples can be found in test folder.
padding	EdgeInsets	EdgeInsets.all(0)	Inner space of the decoration. The pattern will only be drawn inside
backgroundColor	Color	Colors.transparent	Color of the background.
patternColor	Color	Colors.black54	Color of the pattern
lineWidth	double	1.0	Line width for the pattern. In case of dots this is used for the radius.
numberOfLines	int	0	Number of lines. In case of the chequered pattern the vertical distance is used for the horizontal distance as well.

PencilDisplay

Name	Type	Default	Description
key	Key?		Assign key to PencilField widget
pencilDrawing	PencilDrawing	Always required	The drawing that shall be displayed
decoration	PencilDecoration?		Style of the background.

PencilDrawing

Name	Type	Default	Description
strokes	<PencilStrokes>[]	Always required	Initial set of strokes. Can be an empty array.

PencilDrawing also lets you save (toJson) and load (fromJson) a drawing. It also provides its own versioning mechanism to ensure compatibility with future version.

Additional information

A full example is provided in the repository.

Upcoming features

• Additional eraser that only erases strokes within a circle
• Pan support for the input widget and the display widget
• Pinch support for the display widget
• Input widget decoration that supports images as background