Get Android Back Button event

[feinstein]

In my application I want to disable the back button, but I want the user to be able to pop the current screen if he click the AppBar back button.

Basically I have a form inside a PageView, so at each new form field, the PageView moves forward, the back button is supposed to go back one step and not pop the entire form from the screen. But still, if the user wants to pop out, he can using the back button at the top.

Currently we can only do it using WillPopScope, but this isn't enough, as WillPopScope doesn't differentiate between a physical Back button press or an AppBar's back button press.

[ja2375]

You can always handle the back button event yourself:

AppBar(
    leading: IconButton(
        icon: Icon(Icons.arrow_back),
        onPressed: () => Navigator.of(context).pop(),
    ), 
    title: Text("Sample"),
)

[feinstein]

That handles the AppBar back button, not the physical Android Back button.

Thats exactly what I did in my code, I handle the AppBar in one part and WillPopScope in another, but that's not convenient, you are not handling Android's Back button directly, you are solving the problem assembling other solutions together and I think Flutter could do better and simpler.

[ja2375]

In fact this could be implemented in Flutter, but i think this is not convenient as Flutter not only supports Android but many other platforms. And Android is the only platform having a dedicated back button, so implementing this would not make much sense. Handling the AppBar's back event and using WillPopScope makes more sense when compiling for all platforms, not just Android.
If Flutter provided a way to control Android's back button events, you would need to write extra code to support every other platform.

That's my personal opinion.

[feinstein]

Flutter sometimes have properties that only make sense on Android or iOS, like with TextInputAction.

The Android Back button could be implemented in a generic way, the same way we can could get a mouse button press event, it could be a form of system button, or something like it.