Compose Previews as a Power User

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Compose Previews as a Power User Chennai Subhrajyoti Sen Motive

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Simple Previews

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@Composable fun BorrowedItemRowPreview() { BorrowedItemRow( item = BorrowItem( id = 0, itemName = "XBox Series X", borrowerName = "Steve", borrowDate = "2-11-2023" ) ) }

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@Preview @Composable fun BorrowedItemRowPreview() { BorrowedItemRow( item = BorrowItem( id = 0, itemName = "XBox Series X", borrowerName = "Steve", borrowDate = "2-11-2023" ) ) }

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@Preview @Composable fun BorrowedItemRowPreview() { BorrowedItemRow( item = BorrowItem( id = 0, itemName = "XBoz Series X", borrowerName = "Steve", borrowDate = "2-11-2023" ) ) }

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Available Arguments ● name ● group ● uiMode ● locale ● showSystemUi ● showBackground ● device ● apiLevel

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Dark Mode

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@Preview(uiMode = UI_MODE_NIGHT_YES) @Composable fun BorrowedItemRowDevicePreview() { BorrowTheme { BorrowedItemRow( item = //.. ) } }

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Multi Preview Annotation

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@Preview(uiMode = UI_MODE_NIGHT_NO) @Preview(uiMode = UI_MODE_NIGHT_YES) @Composable fun BorrowedItemRowDevicePreview() { BorrowTheme { BorrowedItemRow( item = //.. ) } }

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@Preview(uiMode = UI_MODE_NIGHT_NO) @Preview(uiMode = UI_MODE_NIGHT_YES) annotation class LightDarkThemePreview

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@LightDarkThemePreview @Composable fun BorrowedItemRowDevicePreview() { BorrowTheme { BorrowedItemRow( item = //.. ) } }

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@LightDarkThemePreview @Composable fun BorrowedItemRowDevicePreview() { BorrowTheme { BorrowedItemRow( item = //.. ) } }

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@Preview( showSystemUi = true, device = Devices.NEXUS_5X ) @Preview( showSystemUi = true, device = Devices.NEXUS_10 ) annotation class MultiDevicePreview

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@Preview( showSystemUi = true, device = Devices.NEXUS_5X ) @Preview( showSystemUi = true, device = Devices.NEXUS_10 ) annotation class MultiDevicePreview

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@Preview(locale = "en") @Preview(locale = "fr-rCA") @Preview(locale = "es-rUS") annotation class MultiLocalePreview Valid locale format: https://developer.android.com/guide/topics/resources/provid ing-resources#LocaleQualifier

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@LightDarkThemePreview @MultiLocalePreview annotation class MultiLocaleLightDarkPreview

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Dataset Driven Preview

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@Preview @Composable fun BorrowedItemRowPreview() { BorrowedItemRow( item = BorrowItem( id = 0, itemName = "XBox Series X", borrowerName = "Steve", borrowDate = "2-11-2023" ) ) } @Preview @Composable fun BorrowedItemRowPreview() { BorrowedItemRow( item = BorrowItem( id = 0, itemName = "PlayStation", borrowerName = "Steve", borrowDate = "2-11-2023" ) ) }

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class BorrowItemsProvider : PreviewParameterProvider { override val values = sequenceOf( BorrowItem( id = 0, itemName = "PlayStation", borrowerName = "Steve", borrowDate = "2-11-2022" ), BorrowItem( id = 0, itemName = "XBox", borrowerName = "Steve", borrowDate = "2-11-2022" ) ) }

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@Preview @Composable fun BorrowedItemRowPreview( @PreviewParameter(BorrowItemsProvider::class) item: BorrowItem ) { BorrowedItemRow( item ) }

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@Preview @Composable fun BorrowedItemRowPreview( @PreviewParameter(BorrowItemsProvider::class) item: BorrowItem ) { BorrowedItemRow( item ) }

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Declutter using Groups

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@MultiLocaleLightDarkPreview @Composable fun BorrowedItemRowDevicePreview() { BorrowTheme { BorrowedItemRow( item = //.. ) } }

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@Preview(locale = "en", group = "English") @Preview(locale = "fr-rCA", group = "Canadian French") @Preview(locale = "es-rUS", group = "US Spanish") annotation class MultiLocalePreview

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Local Inspection

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@Composable fun BorrowedItemRow(item: BorrowItem) { var expanded by remember { mutableStateOf(false) } // this will only affect previews if (LocalInspectionMode.current) { expanded = true } //.. }

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@Composable fun BorrowedItemRow(item: BorrowItem) { var expanded by remember { mutableStateOf(false) } // this will only affect previews if (LocalInspectionMode.current) { expanded = true } //.. }

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Showkase

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@ShowkaseComposable(group = "Individual rows") @Preview @Composable fun BorrowedItemRowExpandedPreview() { BorrowTheme { BorrowedItemRow( //.. ) } }

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@ShowkaseComposable(group = "Individual rows") @Preview @Composable fun BorrowedItemRowExpandedPreview() { BorrowTheme { BorrowedItemRow( //.. ) } }

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@ShowkaseComposable(group = "Individual rows") @Composable @Preview fun BorrowedItemRowCollapsedPreview() { CompositionLocalProvider(LocalInspectionMode provides false) { BorrowTheme { BorrowedItemRow( //.. ) } } }

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Animation Previews

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updateTransition Supported Animations AnimatedVisibility animate*AsState rememberInfiniteTransition CrossFade AnimatedContent

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Screenshot Testing

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Available Options

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Paparazzi Available Options

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Paparazzi Roborazzi Available Options

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Paparazzi Roborazzi Compose Preview Available Options

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Paparazzi

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Works on JVM Paparazzi

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Works on JVM Based on Layoutlib Paparazzi

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Works on JVM Based on Layoutlib Needs JUnit tests Paparazzi

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Works on JVM Based on Layoutlib Needs JUnit tests Paparazzi Supports Views

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Works on JVM Based on Layoutlib Needs JUnit tests Paparazzi Supports Views Emulates Production

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class PaparazziTests { @get:Rule val paparazzi = Paparazzi( deviceConfig = PIXEL_5.copy(nightMode = NightMode.NIGHT), renderingMode = RenderingMode.SHRINK ) }

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class PaparazziTests { @get:Rule val paparazzi = Paparazzi( deviceConfig = PIXEL_5.copy(nightMode = NightMode.NIGHT), renderingMode = RenderingMode.SHRINK ) }

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class PaparazziTests { //.. @Test fun launchComposable() { paparazzi.snapshot { BorrowTheme { BorrowedItemRow( item = //.. ) } } } }

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class PaparazziTests { //.. @Test fun launchComposable() { paparazzi.snapshot { CompositionLocalProvider(LocalInspectionMode provides true) { BorrowTheme { BorrowedItemRow( item = //.. ) } } } } }

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class PaparazziTests { //.. @Test fun launchComposable() { paparazzi.snapshot { CompositionLocalProvider(LocalInspectionMode provides true) { BorrowTheme { BorrowedItemRow( item = //.. ) } } } } }

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Baseline

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After changes

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Failure Comparison

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Compose Preview Screenshot

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Works on JVM Compose Preview Screenshot

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Works on JVM Based on Layoutlib Compose Preview Screenshot

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Works on JVM Based on Layoutlib Fully Automated Compose Preview Screenshot

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Works on JVM Based on Layoutlib Fully Automated Compose Preview Screenshot Needs a special directory

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Works on JVM Based on Layoutlib Fully Automated Compose Preview Screenshot Needs a special directory Emulates Debug

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Compose Preview Screenshot - Source

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Compose Preview Screenshot - Source @LightDarkThemePreview @Composable fun BorrowedItemRowPreview( @PreviewParameter(BorrowItemsProvider::class) item: BorrowItem ) { BorrowedItemRow( item ) }

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Compose Preview Screenshot - Destination

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Screen Comparison

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Screen Comparison

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Can’t decide? sergio-sastre/ComposablePreviewScanner

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Further Exploration https://github.com/takahirom/roborazzi Composable Preview Driven Development: TDD-fying your UI with ease!