Jetpack Compose

Oct 11 2022 · Kotlin 1.7.10, Android 13, Android Studio Chipmunk

Part 1: Jetpack Compose Basics

08. Build Common UI Components - Part 3

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Previous episode: 07. Build Common UI Components - Part 2 Next episode: 09. Apply Error & Data Handling to the UI

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Notes: 08. Build Common UI Components - Part 3

The student materials have been reviewed and are updated as of September 2022.

In ui/reviews/ui/BookReviewsList file, within BookReviewItem() composable function, replace CoilImage() composable by AsyncImage() composable with updated parameters. CoilImage composable is old and not compatible with current Jetpack Compose version.

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Demo

Last thing that you have to build in this three-part chunk of episodes, is the BookReviews and AddBookReview features.

@Composable
fun BookPicker(
  books: List<BookAndGenre>,
  selectedBookId: String,
  onItemPicked: (BookAndGenre) -> Unit
) {
  val isPickerOpen = remember { mutableStateOf(false) }
  val selectedBookName =
    books.firstOrNull { it.book.id == selectedBookId }?.book?.name ?: "None"

  Row(verticalAlignment = Alignment.CenterVertically) {
    TextButton(
      onClick = { isPickerOpen.value = true },
      content = { Text(text = stringResource(id = R.string.genre_select)) })

    DropdownMenu(
      expanded = isPickerOpen.value,
      onDismissRequest = { isPickerOpen.value = false }) {

      for (book in books) {
        DropdownMenuItem(onClick = {
          onItemPicked(book)
          isPickerOpen.value = false
        }) {
          Text(text = book.book.name)
        }
      }
    }

    Text(text = selectedBookName)
  }
}

private val _books = mutableStateOf(emptyList<BookAndGenre>())

  override fun onCreate(savedInstanceState: Bundle?) {
	...
    loadBooks()
  }

  private fun loadBooks() {
    lifecycleScope.launch {
      _books.value = repository.getBooks()
    }
  }



  @Composable
  fun AddBookReviewForm() {
	...
    val currentRatingFilter = remember { mutableStateOf(0) }
    val currentlySelectedBook = remember { mutableStateOf(EMPTY_BOOK_AND_GENRE) }
      
    ...
      
    BookPicker(books = _books.value,
      selectedBookId = currentlySelectedBook.value.book.id,
      onItemPicked = { bookAndGenre ->
      _bookReviewState.value = _bookReviewState.value?.copy(bookAndGenre = bookAndGenre)
      currentlySelectedBook.value = bookAndGenre
    })
      
    ...
  }

RatingBar(
  modifier = Modifier.align(CenterHorizontally),
  range = 1..5,
  currentRating = currentRatingFilter.value,
  isLargeRating = true,
  onRatingChanged = { newRating -> currentRatingFilter.value = newRating })

val bookReviewsState = mutableStateOf(emptyList<BookReview>())

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
  super.onViewCreated(view, savedInstanceState)

  lifecycleScope.launch {
    bookReviewsState.value = repository.getReviews()
  }
}

@Composable
fun BookReviewsContentWrapper() {
  val bookReviews = bookReviewsState.value

  BookReviewsList(bookReviews, onItemClick = ::onItemSelected)
}

@Composable
fun BookReviewsList(
  bookReviews: List<BookReview>,
  onItemClick: (BookReview) -> Unit
) {
  LazyColumn {
    items(bookReviews) { bookReview ->
      BookReviewItem(bookReview = bookReview, onItemClick)
    }
  }
}

Card(
    elevation = 8.dp,
    border = BorderStroke(1.dp, MaterialTheme.colors.primary),
    shape = RoundedCornerShape(16.dp),
    modifier = Modifier
      .wrapContentHeight()
      .padding(16.dp)
  ) {

Card(
    elevation = 8.dp,
    border = BorderStroke(1.dp, MaterialTheme.colors.primary),
    shape = RoundedCornerShape(16.dp),
    modifier = Modifier
      .wrapContentHeight()
      .padding(16.dp)
      .clickable(
        onClick = { onItemClick(bookReview) },
        indication = null
      )
  ) {
    Row(modifier = Modifier.fillMaxSize()) {
      Spacer(modifier = Modifier.width(16.dp))

      Column(
        modifier = Modifier
          .weight(0.6f)
          .fillMaxHeight()
      ) {}

      Spacer(modifier = Modifier.width(16.dp))

      Card(
        modifier = Modifier.weight(0.4f),
        shape = RoundedCornerShape(
          topEnd = 16.dp,
          topStart = 16.dp,
          bottomStart = 0.dp,
          bottomEnd = 16.dp
        ),
        elevation = 16.dp
      ) {
          AsyncImage(
            model = bookReview.review.imageUrl,
            contentScale = ContentScale.FillWidth,
            contentDescription = null
          )
      }

Spacer(modifier = Modifier.height(16.dp))

Text(
  text = bookReview.book.name,
  color = MaterialTheme.colors.primary,
  fontSize = 18.sp,
  fontWeight = FontWeight.Bold
)

Spacer(modifier = Modifier.height(8.dp))

Row {
  Text(
    text = stringResource(id = R.string.rating_text)
  )
...
}

  RatingBar(
    modifier = Modifier.align(CenterVertically),
    range = 1..5,
    currentRating = bookReview.review.rating,
    isSelectable = false,
    isLargeRating = false
  )
}

Text(
  text = stringResource(
  id = R.string.number_of_reading_entries,
  bookReview.review.entries.size
))

Spacer(modifier = Modifier.height(8.dp))

Text(
  text = bookReview.review.notes,
  fontSize = 12.sp,
  modifier = Modifier.fillMaxSize(),
  overflow = TextOverflow.Ellipsis,
  fontStyle = FontStyle.Italic,
  maxLines = 4
)

Spacer(modifier = Modifier.height(16.dp))