progress property Null safety
final
The offset ratio of the dismissible in its parent container.
A value of 0.0 represents the normal position and 1.0 means the child is completely outside its parent.
This can be used to synchronize other elements to what the dismissible is doing on screen, e.g. using this value to set the opacity thereby fading dismissible as it's dragged offscreen.
Implementation
final double progress;