Resizing

  final Box rect = Box.fromLTWH(50, 50, 100, 100);
  final ResizeResult result = BoxTransformer.resize(
    handle: HandlePosition.bottomRight,
    initialRect: rect,
    initialLocalPosition: Vector2.zero(),
    localPosition: Vector2.zero(),
    resizeMode: ResizeMode.freeform,
    initialFlip: Flip.none,
  );

  result.rect; // the new rect

BoxTransformer.resize returns a ResizeResult object that contains information about the resized box. result.rect is a Box that defines the new position of the box.

Resizing is freeform by default, meaning that the user can resize the box in any direction and in any size. You can pass ResizeMode.scale to BoxTransformer.resize to limit the resizing to a specific direction.

See Resize Modes for more information about different resizing modes.

Flipping

By default, resizing allows flipping the rect horizontally and vertically. result.rawSize contains information about flipping. Negative values indicate that the rect has been flipped on that axis. e.g. result.rawSize.width is negative if the rect has been flipped horizontally.

Flipping the rect while resizing

While resizing, the rect can be flipped horizontally and vertically whenever the user drags a handle beyond the opposite side of the rect. This allows more flexibility in resizing the box. However, this is not responsible for flipping the content of the box.

This behavior can be disabled by setting allowBoxFlipping to false.

  final Box rect = Box.fromLTWH(50, 50, 100, 100);
  final ResizeResult result = BoxTransformer.resize(
    handle: HandlePosition.bottomRight,
    initialRect: rect,
    initialLocalPosition: Vector2.zero(),
    localPosition: Vector2.zero(),
    resizeMode: ResizeMode.freeform,
    initialFlip: Flip.none,
    allowBoxFlipping: false, // disables flipping the rect while resizing
  );

  result.rect; // the new rect

Constraints

Resizing can be constrained by providing any desirable combination of minHeight, minWidth, maxHeight and maxWidth using the constraints property.

  final Box rect = Box.fromLTWH(50, 50, 100, 100);
  final ResizeResult result = BoxTransformer.resize(
    handle: HandlePosition.bottomRight,
    initialRect: rect,
    initialLocalPosition: Vector2.zero(),
    localPosition: Vector2.zero(),
    resizeMode: ResizeMode.freeform,
    initialFlip: Flip.none,
    constraints: Constraints(
      minWidth: 100,
      minHeight: 100,
      maxWidth: 500,
      maxHeight: 500,
    ),
  );

  result.rect; // the new rect

This will disallow the box from growing or shrinking beyond 100x100 and 500x500 pixels.

ResizeResult also provides information about whether the resizing was constrained or not. ResizeResult.minWidthReached, ResizeResult.minHeightReached, ResizeResult.maxWidthReached and ResizeResult.maxHeightReached are bool values that indicate whether the resizing was constrained or not.

Resizing a rotated box

BoxTransformer.resize accepts rotation (radians around the box's center) and bindingStrategy parameters and dispatches to dedicated rotated paths internally. Freeform, scale, symmetric, symmetricScale, side handles, and force-flip all stay correct under arbitrary rotation:

  final ResizeResult result = BoxTransformer.resize(
    handle: HandlePosition.bottomRight,
    initialRect: Box.fromLTWH(50, 50, 100, 100, rotation: 0.4),
    initialLocalPosition: gestureStartCursor,
    localPosition: currentCursor,
    resizeMode: ResizeMode.freeform,
    initialFlip: Flip.none,
    rotation: 0.4,
    bindingStrategy: BindingStrategy.boundingBox,
    clampingRect: clamp,
    constraints: constraints,
    allowFlipping: true,
  );

ResizeResult.feasible is false when the engine could not satisfy the requested target — the caller should hold its last feasible state instead of writing the returned rect (which is a gesture-start sentinel). Force-flip into an infeasible state automatically falls back to the natural (un-flipped) direction so the rect tracks the cursor by clamp-pinning at the natural wall instead of leaking.

See Rotating and Binding Strategies for the rotation-specific semantics.