How do people handle full screen ` Preview`s I have seen opi kotlinlang #compose

How do people handle full screen `@Preview`s? I have seen opinions previews should only be used for individual composables, not screens, but I also think the XML layout previews were useful and I would like a preview of an entire screen.

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I have a screen that contains a composable that cannot run in a preview. In the View world I would use

isInEditMode()

in it to correctly handle that, but with Compose it just prevents my entire screen from being previewable?

allan.conda

12/02/2021, 6:12 PM

Why can’t it run in preview?

You can try

LocalInspectionMode.current

which is similar to that Edit Mode

Marcin Wisniowski

12/02/2021, 6:22 PM

Why can’t it run in preview?

It's a map view (think Google Maps), there would need to be a lot of mocking just for it to display nothing in the end. I'd rather just not display it.

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You can try
LocalInspectionMode.current
which is similar to that Edit Mode

I haven't seen that, thanks!

allan.conda

12/02/2021, 6:33 PM

Preview is nice, but don’t you want to test your Screen as well? How about refactoring that map subcomponent into a Slot, you can test the rest.

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Chris Sinco [G]

12/02/2021, 7:52 PM

I’m not sure if MapView is supported in Compose preview - @nosuid can comment

But as far as previewing a “screen”, it’s really a Composable with a device set in the Preview parameters, e.g. Pixel3

You can also change height and width of the Preview with individual parameters

Marcin Wisniowski

12/03/2021, 6:39 AM

The map Composable I am using is from a third party library, not from Google.

Chris Sinco [G]

12/03/2021, 7:26 AM

What errors are you getting from the Preview?

Marcin Wisniowski

12/03/2021, 7:40 AM

No errors, my question was just about the problem of having a Composable that has complex dependencies, that would require a lot of code in the @Preview function to stub in a way where it wouldn't crash.

LocalInspectionMode.current

solves this because I can disable the Composable to prevent it from crashing. In this case the Composable takes a function that produces an

InputStream

for a map tile that it then draws. Unless I can produce `InputStream`s in the @Preview function that can be read as valid PNG's the Composable won't work.

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