EdgeInsets insets

The insets of the texture as normalized values. The insets define the areas of the texture that will not be deformed as the sprite stretches.

Source

EdgeInsets get insets => _insets;
void insets=(EdgeInsets insets)

Source

set insets(EdgeInsets insets) {
  assert(insets != null);
  _insets = insets;
  _isDirty = true;
}