DrawingController class

The core controller for the drawing engine.

Manages all drawing state, gesture handling, undo/redo, and shape manipulation. Uses ChangeNotifier to efficiently notify listeners of state changes.

Usage

final controller = DrawingController();
// ... use with DrawingCanvas widget
controller.dispose();

Inheritance

Object
ChangeNotifier
DrawingController

Constructors

DrawingController({DrawingConfig config = const DrawingConfig()})

Properties

activeHandle → ResizeHandle: no setter
canRedo → bool: no setter
canUndo → bool: no setter
canvasOffset ↔ Offset: getter/setter pair
canvasScale ↔ double: getter/setter pair
config → DrawingConfig: Engine configuration.
final
currentShape ↔ ShapeType: getter/setter pair
currentTool ↔ Tool: getter/setter pair
drawMode ↔ DrawMode: getter/setter pair
drawnShapes → List<DrawnShape>: Mutable shapes list — use for direct manipulation (e.g., adding shapes). Prefer addShape, removeShape for tracked operations.
no setter
endPoint → Offset?: no setter
eraserPosition → Offset?: no setter
handleRadius → double: no setter
hashCode → int: The hash code for this object.
no setterinherited
hasListeners → bool: Whether any listeners are currently registered.
no setterinherited
interactionMode ↔ InteractionMode: getter/setter pair
isDrawing → bool: no setter
isResizing → bool: no setter
isSnappingEnabled → bool: no setter
measurementEnd → Offset?: no setter
measurementStart → Offset?: no setter
measurementValue → String: no setter
onSelectionChanged ↔ void Function(DrawnShape? shape)?: Called when a shape is selected or deselected.
getter/setter pair
onShapeAdded ↔ void Function(DrawnShape shape)?: Called when a shape is added.
getter/setter pair
onShapesCleared ↔ VoidCallback?: Called when shapes are cleared.
getter/setter pair
onShapeTextEditRequested ↔ void Function(DrawnShape shape)?: Called when a shape's text needs editing.
getter/setter pair
onTextInputRequested ↔ void Function(Offset position)?: Called when the engine needs text input (e.g., the Text tool was tapped).
getter/setter pair
redoCount → int: no setter
revision → int: no setter
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
selectedShape ↔ DrawnShape?: getter/setter pair
shapes → List<DrawnShape>: Read-only view of the current shapes.
no setter
showGrid ↔ bool: getter/setter pair
showPropertyPanel ↔ bool: getter/setter pair
startPoint → Offset?: no setter
strokeColor ↔ Color: getter/setter pair
strokeWidth ↔ double: getter/setter pair
suggestedShapes → List<ShapeType>?: no setter
suggestionPosition → Offset?: no setter
undoCount → int: no setter

Methods

acceptSuggestion(ShapeType type) → void: Accepts a shape suggestion — replaces the last freehand with the recognized shape.
addListener(VoidCallback listener) → void: Register a closure to be called when the object changes.
inherited
addShape(DrawnShape shape) → void: Adds a shape and notifies listeners.
clearAll() → void: Clears all shapes (saves undo state first).
deleteSelectedShape() → void: Deletes the currently selected shape.
discardSuggestion() → void: Discards the current shape suggestion.
dispose() → void: Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener will throw after the object is disposed).
override
duplicateSelectedShape() → void: Duplicates the currently selected shape with an offset.
exportAsPNG(GlobalKey<State<StatefulWidget>> canvasKey, {int pixelRatio = 1}) → Future<Uint8List?>: Exports the canvas as a PNG byte array.
flipHorizontal() → void: Flips the selected shape horizontally.
flipVertical() → void: Flips the selected shape vertically.
handleLongPressStart(Offset pos) → void: Called on long-press start.
handlePanEnd() → void: Called when a pan gesture ends.
handlePanStart(Offset pos) → void: Called when a pan gesture starts.
handlePanUpdate(Offset pos, Offset delta) → void: Called when a pan gesture updates.
handleScaleUpdate(double scale, Offset focalPoint) → void: Handles pinch-to-zoom gestures.
handleTapDown(Offset pos) → void: Called on tap down events.
layerDown() → void: Moves the selected shape down one layer.
layerUp() → void: Moves the selected shape up one layer.
loadFromJson(String jsonString) → void: Loads shapes from a JSON string.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
notifyListeners() → void: Call all the registered listeners.
inherited
redo() → void: Redoes the last undone action.
removeListener(VoidCallback listener) → void: Remove a previously registered closure from the list of closures that are notified when the object changes.
inherited
removeShape(DrawnShape shape) → void: Removes a shape and notifies listeners.
resetView() → void
rotateSelectedShape() → void: Rotates the selected shape by 45°.
saveStateForUndo() → void: Stores the current shapes for undo. Call before mutations.
toggleSnapping() → void: Toggles magnetic snapping on/off.
toJson() → String: Serializes all shapes to a JSON string.
toString() → String: A string representation of this object.
inherited
undo() → void: Undoes the last action.
updateState() → void: Triggers a manual refresh of the engine UI.
zoomIn() → void: Zoom controls.
zoomOut() → void

Operators

operator ==(Object other) → bool: The equality operator.
inherited