What is the difference between enterAnim & popEnterAnim & exitAnim & popExitAnim?

问题

What is the difference between animation tags in latest Navigation Architecture Component? I got confused with enterAnim & popEnterAnim. Similarly, exitAnim & popExitAnim.

Any visual expansions is more than welcomed.

回答1:

The Animate transitions between destinations documentation details the four types of animations:

• Entering a destination
• Exiting a destination
• Entering a destination via a pop action
• Exiting a destination via a pop action

"Entering" refers to the destination that is coming onto the screen, while "exiting" refers to the destination leaving the screen.

Therefore when you navigate from destination A to destination B, the entering destination B will have the enterAnim applied to it and the exiting destination A will have the exitAnim applied to it.

When the user hits the system Back button, going from B back to A, the reverse happens: the entering destination A will have the popEnterAnim applied to it and the exiting destination B will have the popExitAnim applied to it.

回答2:

Pop is related to the back stack, I use back stack for helping understanding

e.g.

A is showing on screen now, we are going to put B on screen, then A will Exit(Anim/transaction) from screen, B will Enter to screen.

Now what’s going to happen if you tap back key/up button? Yes, the reverse happens. Which means B is going to be replaced by A.

• B is popped off the back stack and Exit from screen (Pop Exit)
• A is entered to the view from the back stack (Pop Enter)

来源：https://stackoverflow.com/questions/56285197/what-is-the-difference-between-enteranim-popenteranim-exitanim-popexitanim