Flutter Flow Chart

A package that let you draw a flow chart diagram with different kind of customizable elements. Dashboards can be saved for later use.

See online example here

Features

diamond, rectangle, oval, storage, parallelogram elements
elements can be customizable with background, border and text color, border thickness, text size and weight.
interactively connect elements
save/load dashboard

Usage

First create a Dashboard:

Dashboard dashboard = Dashboard();

then crete the [FlowChart] widget where you can react to the user interactions:

FlowChart(
    dashboard: dashboard,
    onDashboardTapped: ((context, position) {}),
    onDashboardLongtTapped: ((context, position) {}),
    onElementLongPressed: (context, element) {},
    onElementPressed: (context, element) {},
    onHandlerPressed: (context, position, handler, element) {},
    onHandlerLongPressed: (context, position, handler, element) {},
)

then use the dashboard variable to add, remove, resize etc. elements or load/save the dashboard.

In the example, the StarMenu package is used to easily interact with user inputs.

The Dashboard

The Dashboard object contains all the methods described below used to interact with the flow chart.

relevant methods	description
setGridBackgroundParams	set grid background parameters
setHandlerFeedbackOffset	set the feedback offset to help on mobile device to see the end of arrow and not hiding behind the finger when moving it
setElementResizable	set the element as resizable. A handle will be displayed on the bottom right and will disappear when finish resizing
addElement	add a FlowElement to the dashboard
removeAllElements	remove all elements
removeElementConnection	remove the given handler connection of the given element
removeElementConnections	remove all the connections from the given element
removeElementById	remove all the elements with the given id from the dashboard
removeElement	remove the given element
addNextById	make a connection from the given sourceElement to the elements with the given id
saveDashboard	save the dashboard into the given file path
loadDashboard	clear the dashboard and load the new one

The FlowElement

The FlowElement defines the element kind with its position, size, colors and so on.

properties	type	description
position	Offset	The position of the FlowElement
size	Size	The size of the FlowElement
text	String	Element text
textColor	Color	Text color
textSize	double	Text size
textIsBold	bool	Makes text bold if true
kind	ElementKind	Element shape: enum {rectangle, diamond, storage, oval, parallelogram}
handlers	List	Connection handlers: enum {topCenter, bottomCenter, rightCenter, leftCenter}
handlerSize	Size	The size of element handlers
backgroundColor	Size	Background color of the element
borderColor	Size	Border color of the element
borderThickness	Size	Border thickness of the element
elevation	Size	Shadow elevation
next	List	Shadow elevation

relevant methods	description
setIsResizing	When setting to true, a handler will disply at the element bottom right to let the user to resize it. When finish it will disappear.
setText	Set element text
setTextColor	Set text color
setTextSize	Set text size
setTextIsBold	Set text bold
setBackgroundColor	Set background color
setBorderColor	Set border color
setBorderThickness	Set border thickness
setElevation	Set elevation
changePosition	Change element position in the dashboard
changeSize	Change element size

Examples

Add an element to Dashboard

Dashboard dashboard = Dashboard();

///////////////////////////////////
/// Define 2 elements
FlowElement element1 = FlowElement(
    /// position in the local dashboard coordinates
    position: const Offset(100, 100),
    /// element size
    size: const Size(100, 100),
    /// text to show
    text: 'diamond',
    /// rectangle, diamond, storage, oval or parallelogram element kind
    kind: ElementKind.diamond,
    /// which handler to make active
    handlers: [
        Handler.bottomCenter,
        Handler.topCenter,
        Handler.leftCenter,
        Handler.rightCenter,
    ]);
FlowElement element2 = FlowElement(
    position: const Offset(300, 100),
    size: const Size(100, 150),
    text: 'rect',
    kind: ElementKind.rectangle,
    handlers: [
        Handler.bottomCenter,
        Handler.topCenter,
        Handler.leftCenter,
        Handler.rightCenter,
    ]);
///////////////////////////////////
/// Add the element to Dashboard
dashboard.addElement(element);

///////////////////////////////////
/// Connect right handler of element1 
/// to the left handler of element2
dashboard.addNextById(
    element1,
    element2.id,
    ArrowParams(
        thickness: 1.5,
        color: Colors.Black,
        startArrowPosition: Alignment.centerRight,
        endArrowPosition: Alignment.centerLeft,
    ),
);

///////////////////////////////////
/// Save/load dashboard
Directory appDocDir =
    await path.getApplicationDocumentsDirectory();

dashboard.saveDashboard('${appDocDir.path}/FLOWCHART.json');

dashboard.loadDashboard('${appDocDir.path}/FLOWCHART.json');