草图流程

Sketch Flow

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A powerful and flexible Flutter sketching plugin
Easily build drawing applications with elegant UI and comprehensive export features.

Features

Easy-to-use SketchController

• Integrate sketching functionality with just a few lines using SketchController. Manage tools, undo/redo, and export effortlessly.

Export Support

• PNG: For high-resolution image rendering
• SVG: For scalable vector graphics
• JSON: For precise stroke data and replaying paths

Built-in Stylish UI

• Comes with ready-made top/bottom bars that offer a clean, user-friendly design.
• Use directly without extra customization for quick prototyping.

Preview

Test it live!: Try it
View example code: main.dart
Check out an example project using sketch_flow: sketch_flow_example

Core components at a glance

Components	Description
SketchController	(Required) Key controller that manages drawing status and can be extracted in various formats such as JSON/SVG/PNG
SketchBoard	(Required) Main canvas widget to handle user input (draw/er, etc.)
SketchTopBar / SketchBottomBar	(Optional) Preferred UI components

Architecture

How to Use sketch_flow

Install the package

• Add this to your pubspec.yaml: Check latest version

dependencies:
  sketch_flow: ^latest_version

SketchController and SketchBoard

• SketchController is a key class that manages drawing data.
  By passing this controller to SketchBoard, you can process user input, extract or reload the information you need.

final SketchController _controller = SketchController();

• And if you want to extract images with PNG or save the screen, you need to set GlobalKey on SketchBoard.
  This key is internally connected to RepaintBoundary and is used to capture images.

final GlobalKey _repaintKey = GlobalKey();

• After this definition, pass it along to SketchBoard:

SketchBoard(
  controller: _controller,
  repaintKey: _repaintKey,
)

(Optional) Use SketchTopBar and SketchBottomBar

• It's easy to use, and you can customize it in your own style through a variety of parameters.

Scaffold(
  appBar: SketchTopBar(controller: _controller),
  body: SketchBoard(controller: _controller),
  bottomNavigationBar: SketchBottomBar(controller: _sketchController),
)

💡 Of course, you can freely configure the UI.
If you connect the Sketch Controller properly, you can design the UI any way you want without the top and bottom bars.

Export & Import Drawings

JSON (Serialization / Deserialization)

• You can easily serialize (export) your sketch data to JSON and deserialize (import) it back using the controller:

final json = _controller.toJson(); // Serialization

_controller.fromJson(json: json); // Deserialization

PNG

• You can easily export your drawing as a PNG using SketchController.
  Customize the image resolution with the pixelRatio parameter:

final Uint8List? image = await _controller.extractPNG(
  repaintKey: _repaintKey,
  pixelRatio: 2.0, // Customize resolution
);

SVG

• Easily export your drawing as an SVG with SketchController.
  You can define the canvas width and height to match your needs.

final String svgCode = await _controller.extractSVG(
  width: 300.0, // Define canvas width
  height: 400.0, // Define canvas height
);

Tools Overview

Tool Type	Description
Move	Enables panning and zooming of the canvas without affecting the drawings.
Pencil	Draws a continuous line based on user input. Configurable stroke thickness, color, and opacity.
Brush	Simulates a brush-like stroke with smooth edges. Supports color and thickness customization.
Highlighter	Draws semi-transparent strokes resembling a highlighter. Comes with predefined low opacity and medium thickness to simulate real highlighter effects.
Palette	Allows users to select colors for drawing tools.
Eraser	Erases drawings either by stroke or by area.
Line	Draws a straight line between the first and last touch point. Line color and thickness are customizable.
Rectangle	Draws a rectangle defined by the first and last touch points.
Circle	Draws a circle or ellipse bounded by the first and last touch points.