getOffsetY method

Implementation

@override
double getOffsetY(ScaffoldPrelayoutGeometry scaffoldGeometry, double adjustment) {
  final double contentBottom = scaffoldGeometry.contentBottom;
  final double contentMargin = scaffoldGeometry.scaffoldSize.height - contentBottom;
  final double bottomViewPadding = scaffoldGeometry.minViewPadding.bottom;
  final double bottomSheetHeight = scaffoldGeometry.bottomSheetSize.height;
  final double fabHeight = scaffoldGeometry.floatingActionButtonSize.height;
  final double snackBarHeight = scaffoldGeometry.snackBarSize.height;
  final double bottomMinInset = scaffoldGeometry.minInsets.bottom;

  double safeMargin;

  if (contentMargin > bottomMinInset + fabHeight / 2.0) {
    // If contentMargin is higher than bottomMinInset enough to display the
    // FAB without clipping, don't provide a margin
    safeMargin = 0.0;
  } else if (bottomMinInset == 0.0) {
    // If bottomMinInset is zero(the software keyboard is not on the screen)
    // provide bottomViewPadding as margin
    safeMargin = bottomViewPadding;
  } else {
    // Provide a margin that would shift the FAB enough so that it stays away
    // from the keyboard
    safeMargin = fabHeight / 2.0 + kFloatingActionButtonMargin;
  }

  double fabY = contentBottom - fabHeight / 2.0 - safeMargin;
  // The FAB should sit with a margin between it and the snack bar.
  if (snackBarHeight > 0.0) {
    fabY = math.min(fabY, contentBottom - snackBarHeight - fabHeight - kFloatingActionButtonMargin);
  }
  // The FAB should sit with its center in front of the top of the bottom sheet.
  if (bottomSheetHeight > 0.0) {
    fabY = math.min(fabY, contentBottom - bottomSheetHeight - fabHeight / 2.0);
  }
  final double maxFabY = scaffoldGeometry.scaffoldSize.height - fabHeight - safeMargin;
  return math.min(maxFabY, fabY);
}