How to detect swipe in flutter

Use GestureDetector.onPanUpdate:

GestureDetector(
  onPanUpdate: (details) {
    // Swiping in right direction.
    if (details.delta.dx > 0) {}
  
    // Swiping in left direction.
    if (details.delta.dx < 0) {}
  },
  child: YourWidget(),
)

To cover all the area (passing the parent constraints to the widget), you can include SizedBox.expand.

SizedBox.expand(
  child: GestureDetector(
    onPanUpdate: (details) {
      // Swiping in right direction.
      if (details.delta.dx > 0) {}

      // Swiping in left direction.
      if (details.delta.dx < 0) {}
    },
    child: YourWidget(),
  ),
)