[refactor] Use `DevicesPreviews` annotation

[mhmd-android]

Removed individual @Preview functions for different device types and configurations and used the @DevicesPreviews function

123 close

[Kaaveh]

Great job, @mhmd-android! Could you please provide a screenshot of the new previews in Android Studio?

[mhmd-android]

@Kaaveh, Yes sure, but I don't know Why my Android Studio doesn't show the preview, this problem is only in this preview Anyway, previews are like this:

[Kaaveh]

@mhmd-android I faced this issue before, so I made it a GitHub issue. Can you investigate the root cause?

[mhmd-android]

@Kaaveh, As long as I remember, I had this problem and I didn't understand what the problem is, but if you want to merge this PR and after that make it new an issue, if I succeed, I will definitely solve it.

[Kaaveh]

I reviewed the code and noticed that WindowsSizeClass requires the screen size as a parameter. Can you modify it to retrieve the screen size automatically?

[mhmd-android]

I think it cannot be handled with just DevicesPreviews annotation because we have different previews, each of which receives a different width and height, so, do you have any opinions?

[Kaaveh]

Unfortunately, no. However, I think Jetpack Compose has made it easier to preview multiple screens in production. @mhmd-android

[mhmd-android]

@Kaaveh I think this is why we used several previews in the previous code because the value of WindowSizeClassis different in each preview. That DevicesPreviews works when we don't have such a dependency

[Kaaveh]

Right, so let's close this PR. Thanks for your time ✌🏻

[mhmd-android]

Thanks, dear @Kaaveh, And as the last issue, I should point out that we can't use code generation?

[Kaaveh]

Thanks, dear @Kaaveh, And as the last issue, I should point out that we can't use code generation?

What do you mean exactly?

[mhmd-android]

For example, let's write code generation (of course, I have to point out that I have not done this so far) that the annotation takes two inputs as width and height, and then the code is generated for us in the body of ComposeNewsAppPreview as an annotation processor. And then for each size, we can do it like this. In fact, DevicesPreviews turns into an annotation processor.

Something like this code:

@AutoService(Processor::class)
@SupportedSourceVersion(SourceVersion.RELEASE_8)
class DevicesPreviewsProcessor : AbstractProcessor() {
    override fun getSupportedAnnotationTypes(): MutableSet<String> {
        return mutableSetOf(DevicesPreviews::class.java.name)
    }

    override fun process(annotations: MutableSet<out TypeElement>?, roundEnv: RoundEnvironment?): Boolean {
        val generatedCode = StringBuilder()

        roundEnv?.getElementsAnnotatedWith(DevicesPreviews::class.java)?.forEach { element ->
            val annotation = element.getAnnotation(DevicesPreviews::class.java)
            val width = annotation.width
            val height = annotation.height

            generatedCode.appendLine(
                """
                @Composable
                fun ${element.simpleName}() {
                    ComposeNewsTheme {
                        ComposeNewsApp(
                            windowSize = WindowSizeClass.calculateFromSize(DpSize($width.dp, $height.dp)),
                            displayFeatures = persistentListOf(),
                            uiState = MainContract.State(),
                            closeDetailScreen = {},
                        )
                    }
                }
                """
            )
        }
        return true
    }
}

And finally, be used in this way:

@DevicesPreviews(width = 400, height = 900)
@Composable
fun ComposeNewsAppPreview() {
    Generated.ComposeNewsAppPreview()
}

Of course, the problem here is that this annotation processor only produces this part of the code:

               @Composable
                fun ${element.simpleName}() {
                    ComposeNewsTheme {
                        ComposeNewsApp(
                            windowSize = WindowSizeClass.calculateFromSize(DpSize($width.dp, $height.dp)),
                            displayFeatures = persistentListOf(),
                            uiState = MainContract.State(),
                            closeDetailScreen = {},
                        )
                    }
                }

and I think we cannot use it anywhere else.

Anyway, I said, keep this in mind, if you think this is a suitable solution, it should be researched and finally used.

[Kaaveh]

Great idea! Would you like to work on this in the future? There is no rush.

[mhmd-android]

Yes, I would, of course

[Kaaveh]

Yes, I would, of course

Could you please comment on #169 to assign it to you?

[mhmd-android]

Yes, I would, of course

Could you please comment on #169 to assign it to you?

Done 🙌