InteractiveViewer constructor Null safety

InteractiveViewer(
  1. {Key? key,
  2. Clip clipBehavior = Clip.hardEdge,
  3. bool alignPanAxis = false,
  4. EdgeInsets boundaryMargin = EdgeInsets.zero,
  5. bool constrained = true,
  6. double maxScale = 2.5,
  7. double minScale = 0.8,
  8. GestureScaleEndCallback? onInteractionEnd,
  9. GestureScaleStartCallback? onInteractionStart,
  10. GestureScaleUpdateCallback? onInteractionUpdate,
  11. bool panEnabled = true,
  12. bool scaleEnabled = true,
  13. double scaleFactor = 200.0,
  14. TransformationController? transformationController,
  15. required Widget child}
)

Create an InteractiveViewer.

The child parameter must not be null.

Implementation

InteractiveViewer({
  super.key,
  this.clipBehavior = Clip.hardEdge,
  this.alignPanAxis = false,
  this.boundaryMargin = EdgeInsets.zero,
  this.constrained = true,
  // These default scale values were eyeballed as reasonable limits for common
  // use cases.
  this.maxScale = 2.5,
  this.minScale = 0.8,
  this.onInteractionEnd,
  this.onInteractionStart,
  this.onInteractionUpdate,
  this.panEnabled = true,
  this.scaleEnabled = true,
  this.scaleFactor = 200.0,
  this.transformationController,
  required Widget this.child,
}) : assert(alignPanAxis != null),
     assert(child != null),
     assert(constrained != null),
     assert(minScale != null),
     assert(minScale > 0),
     assert(minScale.isFinite),
     assert(maxScale != null),
     assert(maxScale > 0),
     assert(!maxScale.isNaN),
     assert(maxScale >= minScale),
     assert(panEnabled != null),
     assert(scaleEnabled != null),
     // boundaryMargin must be either fully infinite or fully finite, but not
     // a mix of both.
     assert(
       (boundaryMargin.horizontal.isInfinite
         && boundaryMargin.vertical.isInfinite) || (boundaryMargin.top.isFinite
         && boundaryMargin.right.isFinite && boundaryMargin.bottom.isFinite
         && boundaryMargin.left.isFinite),
     ),
     builder = null;