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Description:

flutter flow chart

Flutter Flow Chart #
A package that let you draw a flow chart diagram with different kinds of customizable elements. Dashboards can be saved for later use.

See the 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(
blockDefaultZoomGestures: false, // optional
handlerFeedbackOffset: Offset.zero, // optional
minimumZoomFactor: 1.25, // optional
defaultArrowStyle: ArrowStyle.curve, // optional
);
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Following arrow styles are available

ArrowStyle.curve,
ArrowStyle.segmented,
ArrowStyle.rectangular,

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) {},
onScaleUpdate: (newScale) {},
)
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then use the _dashboard_ variable to add, remove, resize, etc. elements or load/save the dashboard.

In the [example](https://github.com/alnitak/flutter_flow_chart/blob/master/example/lib/main.dart), the [StarMenu](https://pub.dev/packages/star_menu) package is used to easily interact with user inputs.
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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 |
| _recenter_ | Recenter the dashboard relative to the first element in the element array |
| _saveDashboard_ | save the dashboard into the given file path |
| _loadDashboard_ | clear the dashboard and load the new one |
| _setZoomFactor_ | Zoom the entire dashboard and content by the given factor corresponding to the given epicenter |
| _dissectElementConnection_ | Dissect the connection into two segments from the given point. Only available on ArrowStyle.segmented |
| _dissectElementConnection_ | Remove dissection by the given pivot |
| _setArrowStyle_ | Update arrow style for single connection using the source and destination elements |
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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 |
| _fontFamily_ | String | Text font family |
| _textSize_ | double | Text size |
| _textIsBold_ | bool | Makes text bold if true |
| _kind_ | ElementKind | Element shape: enum {rectangle, diamond, storage, oval, parallelogram} |
| _handlers_ | List<Handler> | 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<ConnectionParams> | 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 |
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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');
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