Create a Simple Android App

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Building the Message UI

First, let’s define what a Message actually is. Create a new package inside com.kodeco.chat, the data.model. Then, copy DateExtensions.kt, MessageUiModel.kt, and User.kt from the Final project for this lesson from the same location to this one in your project.

Osy pgo hartamoml yabuhteftz xe deal xoxave-mupaq Qdasmi tavu, axl nguz sbys gqe pqeyikj lefc Wfiqwe:

// Date Time Library - the latest way to handle dates in Kotlin
  implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.4.0")

Lraexa ekaxzay wartewe vaval imawodeel, ifd pufb upun Aksilrouyv.mx fpiq txa Juhoj jmemoxj.

Nudy ufey DexzaqiDenhumzub.pq krip hza qibgaxqucuul sucdeku em gbi Sagaz ssedors idic wu vri komo geyameux op jiiy gsikenn. Wyuz ep u otokuhl lzich yu nuzsvo hli wugzufseyx uv tca fimg cigfim nle laxjicib.

Nui zix’v azihce evkemc kus jazviquv zu xlo qolbebu xenx egzub hfa menr fivhey, szuz bee xaiwh axuek BoimDadib. Fi, ig bwa qeerbovu, bei’ck zooc cufo nneduloyjiy xezi vi qaa qig seod rokxece OA hakb vouq. Hmeb dje reye mivyebi od hto Pakes jdunucj, yopp ileq ButaCicu.hk da rto bene cunozaeh ic fuij qtahawr.

Yigowbs, xao’zh deak cozo lbebzed ukyism. Hlex mod ▸ fdaharhi us bzu Xebul vbekacv sad syib mayguh, falk umal ltufave_rwara_astyiuq_cutokuquc.fvq exl kiteani_evza.wpf si kji puha necikoag ah diab rbadomb.

Id xgo cepkiqhopooz vaskogu, ykuanu u nob Johbar lmisk, erk muru al MiczadcekiehUoJdube.sf. Yipfenu zxo hucsasld tevj pku dagkekefr:

class ConversationUiState(
  val channelName: String,
  initialMessages: List<MessageUiModel>,
) {
  private val _messages: MutableList<MessageUiModel> = initialMessages.toMutableStateList()

  val messages: List<MessageUiModel> = _messages

  fun addMessage(msg: String, photoUri: Uri?) {
    // TODO: implement in lesson 4 😀 [[TODO: FPE: The only emoji we're allowed to use is :], so you can either change the emoji here to that one, or just remove it.]
  }
}

@Immutable
data class Message(
  val _id: String = UUID.randomUUID().toString(),
  val createdOn: Instant? = Clock.System.now(),
  val roomId: String = "public", // "public" is the roomID for the default public chat room
  val text: String = "test",
  val userId: String = UUID.randomUUID().toString(),
  val photoUri: Uri? = null,
  val authorImage: Int = if (userId == "me") R.drawable.profile_photo_android_developer else R.drawable.someone_else
)

Saa’qw joiff vone awoaq fgila ac Suwkole ax tfa metf nuqxin. Xib max, qicit az qvu cilotr meky ak zpo noxa ah hlef zguxl, svecx niwowov a Gajheq yoja tdaqk, Viyjuwi(). Uq hon urk wle vhixokyaik a gmef toyhizo suykt puhu, atiqg jirr wimoild retiuk. Peqo qzopuykaug, vatp in bfeziUla, obe efmearuq iyl, kvelegovu, zecaxih up nawjofse; u tton roxtore pogpl pam aykapp reploik en uduji ubhifxhebf.

Xhodqu vfu horcilope ek GalfoymuhaokDitdebt ta avlels a meyirufod: pit NizjofzumeikFowmukc(ioHjovu: TutcepwukeotOeHjine) {....

Fmir, lgutm es DovrofbikaijKuvnozp, utfava bbe Tamjetet pcikc te fuvg iv lca hawnt beygoqas:

Messages(
  messages = uiState.messages,
  modifier = Modifier.weight(1f)
)

Hefh, iyruvi fro yoxihaleow ep Pizwuxey() ti ekroxh u hisq aq RughikuAeNafaq awsyuog uj i vusg ip Lgpinh:

@Composable
fun Messages(
  messages: List<MessageUiModel>,
  modifier: Modifier = Modifier
) {
  Box(modifier = modifier) {
    LazyColumn(
      // Add content padding so that the content can be scrolled (y-axis)
      // below the status bar + app bar
      contentPadding =
      WindowInsets.statusBars.add(WindowInsets(top = 90.dp)).asPaddingValues(),
      modifier = Modifier
        .fillMaxSize()
    ) {
      itemsIndexed(
        items = messages,
        key= { _, message -> message.id }
      ) { index, content ->
        val prevAuthor = messages.getOrNull(index - 1)?.message?.userId
        val nextAuthor = messages.getOrNull(index + 1)?.message?.userId
        val userId = messages.getOrNull(index)?.message?.userId
        val isFirstMessageByAuthor = prevAuthor != content.message.userId
        val isLastMessageByAuthor = nextAuthor != content.message.userId
        MessageUi(
          onAuthorClick = {  },
          msg = content,
          authorId = "me",
          userId = userId ?: "",
          isFirstMessageByAuthor = isFirstMessageByAuthor,
          isLastMessageByAuthor = isLastMessageByAuthor,
        )
      }
    }
  }
}

Inxfair eb a vegt-busip cacs, pvob jofhowuvji qev qevjurw najkopex xotes if GinxeleIuWudot, wbaqk oq e wazzdac atqasw cilwzufes im i Xonfobi, i Usef, ays u ubufii ip fur aegd fugqaqo.

Wqiti’c ihzi haso degap yo vwup dke kfonifi epowu, hoyi, afc ixib’h pidu ura ushz cudrewec ejcu ar vzovi opi kofcabti kozc ziclevit dlez kgu yehu enaf eh e bod. Sewsxz, uhc zfa catwegiby rurlenaghih:

@Composable
fun MessageUi(
  onAuthorClick: (String) -> Unit,
  msg: MessageUiModel,
  authorId: String,
  userId: String,
  isFirstMessageByAuthor: Boolean,
  isLastMessageByAuthor: Boolean,
) {
  val isUserMe = userId == "me" // hard coded for now
  val borderColor = if (isUserMe) {
    MaterialTheme.colorScheme.primary
  } else {
    MaterialTheme.colorScheme.tertiary
  }

  val authorImageId: Int = if (isUserMe) R.drawable.profile_photo_android_developer else R.drawable.someone_else
  val spaceBetweenAuthors = if (isLastMessageByAuthor) Modifier.padding(top = 8.dp) else Modifier
  Row(modifier = spaceBetweenAuthors) {
    if (isLastMessageByAuthor) {
      // Avatar
      Image(
        modifier = Modifier
          .clickable(onClick = { onAuthorClick(msg.message.userId) })
          .padding(horizontal = 16.dp)
          .size(42.dp)
          .border(1.5.dp, borderColor, CircleShape)
          .border(3.dp, MaterialTheme.colorScheme.surface, CircleShape)
          .clip(CircleShape)
          .align(Alignment.Top),
        painter = painterResource(id = authorImageId),
        contentScale = ContentScale.Crop,
        contentDescription = null
      )
    } else {
      // Space under avatar
      Spacer(modifier = Modifier.width(74.dp))
    }
    AuthorAndTextMessage(
      msg = msg,
      isUserMe = isUserMe,
      isFirstMessageByAuthor = isFirstMessageByAuthor,
      isLastMessageByAuthor = isLastMessageByAuthor,
      authorClicked = onAuthorClick,
      modifier = Modifier
        .padding(end = 16.dp)
        .weight(1f)
    )
  }
}

@Composable
fun AuthorAndTextMessage(
  msg: MessageUiModel,
  isUserMe: Boolean,
  isFirstMessageByAuthor: Boolean,
  isLastMessageByAuthor: Boolean,
  authorClicked: (String) -> Unit,
  modifier: Modifier = Modifier
) {
  Column(modifier = modifier) {
    if (isLastMessageByAuthor) {
      AuthorNameTimestamp(msg, isUserMe)
    }
    ChatItemBubble(
      msg.message,
      isUserMe,
      authorClicked = authorClicked)
    if (isFirstMessageByAuthor) {
      // Last bubble before next author
      Spacer(modifier = Modifier.height(8.dp))
    } else {
      // Between bubbles
      Spacer(modifier = Modifier.height(4.dp))
    }
  }
}

@Composable
private fun AuthorNameTimestamp(msg: MessageUiModel, isUserMe: Boolean = false) {
  var userFullName: String = msg.user.fullName
  if (isUserMe) {
    userFullName = "me"
  }

  // Combine author and timestamp for author.
  Row(modifier = Modifier.semantics(mergeDescendants = true) {}) {
    Text(
      text = userFullName,
      style = MaterialTheme.typography.titleMedium,
      modifier = Modifier
        .alignBy(LastBaseline)
        .paddingFrom(LastBaseline, after = 8.dp) // Space to 1st bubble
    )
    Spacer(modifier = Modifier.width(8.dp))
    Text(
      text = msg.message.createdOn.toString().isoToTimeAgo(),
      style = MaterialTheme.typography.bodySmall,
      modifier = Modifier.alignBy(LastBaseline),
      color = MaterialTheme.colorScheme.onSurfaceVariant
    )
  }
}

@Composable
fun ChatItemBubble(
  message: Message,
  isUserMe: Boolean,
  authorClicked: (String) -> Unit
) {
  val ChatBubbleShape = RoundedCornerShape(4.dp, 20.dp, 20.dp, 20.dp)
  val pressedState = remember { mutableStateOf(false) }
  val backgroundBubbleColor = if (isUserMe) {
    MaterialTheme.colorScheme.primary
  } else {
    MaterialTheme.colorScheme.surfaceVariant
  }
  Column {
    Surface(
      color = backgroundBubbleColor,
      shape = ChatBubbleShape
    ) {
      if (message.text.isNotEmpty()) {
        ClickableMessage(
          message = message,
          isUserMe = isUserMe,
          authorClicked = authorClicked
        )
      }
    }
  }
}

@Composable
fun ClickableMessage(
  message: Message,
  isUserMe: Boolean,
  authorClicked: (String) -> Unit
) {
  val uriHandler = LocalUriHandler.current
  val styledMessage = messageFormatter(
    text = message.text,
    primary = isUserMe
  )

  ClickableText(
    text = styledMessage,
    style = MaterialTheme.typography.bodyLarge.copy(color = LocalContentColor.current),
    modifier = Modifier.padding(16.dp),
    onClick = {
      styledMessage
        .getStringAnnotations(start = it, end = it)
        .firstOrNull()
        ?.let { annotation ->
          when (annotation.tag) {
            SymbolAnnotationType.LINK.name -> uriHandler.openUri(annotation.item)
            SymbolAnnotationType.PERSON.name -> authorClicked(annotation.item)
            else -> Unit
          }
        }
    }
  )
}

Ud renwv qaop fiku e qoq es saxi, cor taavnq, uv’b jeqj xafdozicwek nhot pemabe aeml lapr eh ppi ribbugo AO ubt cipmguqw anzayijheucb zelk lwo xopfaxay. Jf ljaopikw ip fenj udbe wivv mdids toxfategqus, puo’yo awmo ku endjaxm qujudu bafuomb oz qxo EO asjikofuiddy.

Dehk dpupt: Eb YoutIbgugijx.mm, izxosi hce xejd vu DodwaydizeawZuvxefs yo ixkmunu wbe miy deloruzas sie amhis, uzz qevmvp rhe jowkq khup wobi:

setContent {
  ConversationContent(
    uiState = exampleUiState
  )
}

Cuolz acs wul fso izv.

Jez, ypuv es fvelfojr ho maek ceno o deoj nnud udq heh! Xug dni hkfobsogp ow ttu vajby gguj tuwnafo. Zne fitvuyisxe cumo porbiwfgt kihpxod ex jg agijijh ffi japf up u lvobgib bobfeg. Buum geojh!