Jetpack Compose UI：如何创建SearchView？ [英] Jetpack Compose UI: How to create SearchView?
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问题描述
我想使用Jetpack Compose创建SearchView，但我找不到任何可以帮助我的示例。提前谢谢。
推荐答案
这是一个复杂但完整的从头开始的SearchView实现。结果将如下面的gif所示，如果您不希望在SearchView未聚焦且为空时显示初始Composable，您可以自定义或移除InitialResults或Suggestions
/**
* Enum class with different values to set search state based on text, focus, initial state and
* results from search.
*
* **InitialResults** represents the initial state before search is initiated. This represents
* the whole screen
*
*/
enum class SearchDisplay {
InitialResults, Suggestions, Results, NoResults
}
2-然后创建定义搜索逻辑的类
@Stable
class SearchState(
query: TextFieldValue,
focused: Boolean,
searching: Boolean,
suggestions: List<SuggestionModel>,
searchResults: List<TutorialSectionModel>
) {
var query by mutableStateOf(query)
var focused by mutableStateOf(focused)
var searching by mutableStateOf(searching)
var suggestions by mutableStateOf(suggestions)
var searchResults by mutableStateOf(searchResults)
val searchDisplay: SearchDisplay
get() = when {
!focused && query.text.isEmpty() -> SearchDisplay.InitialResults
focused && query.text.isEmpty() -> SearchDisplay.Suggestions
searchResults.isEmpty() -> SearchDisplay.NoResults
else -> SearchDisplay.Results
}
override fun toString(): String {
return "🚀 State query: $query, focused: $focused, searching: $searching " +
"suggestions: ${suggestions.size}, " +
"searchResults: ${searchResults.size}, " +
" searchDisplay: $searchDisplay"
}
}
3-请记住，不是每次作文都更新状态，而是仅当我们的搜索状态更改时才更新
@Composable
fun rememberSearchState(
query: TextFieldValue = TextFieldValue(""),
focused: Boolean = false,
searching: Boolean = false,
suggestions: List<SuggestionModel> = emptyList(),
searchResults: List<TutorialSectionModel> = emptyList()
): SearchState {
return remember {
SearchState(
query = query,
focused = focused,
searching = searching,
suggestions = suggestions,
searchResults = searchResults
)
}
}
TutorialSectionModel是我使用的模型它可以是泛型类型T或您希望显示的特定类型
4-创建不显示时要显示的提示focused
@Composable
private fun SearchHint(modifier: Modifier = Modifier) {
Row(
verticalAlignment = Alignment.CenterVertically,
modifier = Modifier
.fillMaxSize()
.then(modifier)
) {
Text(
color = Color(0xff757575),
text = "Search a Tag or Description",
)
}
}
我没有使用Icon，但如果您愿意，可以添加一个
5-创建一个SearchTextfield可以有取消按钮、CircularProgressIndicator显示加载和BasicTextField输入的
/**
* This is a stateless TextField for searching with a Hint when query is empty,
* and clear and loading [IconButton]s to clear query or show progress indicator when
* a query is in progress.
*/
@Composable
fun SearchTextField(
query: TextFieldValue,
onQueryChange: (TextFieldValue) -> Unit,
onSearchFocusChange: (Boolean) -> Unit,
onClearQuery: () -> Unit,
searching: Boolean,
focused: Boolean,
modifier: Modifier = Modifier
) {
val focusRequester = remember { FocusRequester() }
Surface(
modifier = modifier
.then(
Modifier
.height(56.dp)
.padding(
top = 8.dp,
bottom = 8.dp,
start = if (!focused) 16.dp else 0.dp,
end = 16.dp
)
),
color = Color(0xffF5F5F5),
shape = RoundedCornerShape(percent = 50),
) {
CompositionLocalProvider(LocalContentAlpha provides ContentAlpha.medium) {
Box(
contentAlignment = Alignment.CenterStart,
modifier = modifier
) {
if (query.text.isEmpty()) {
SearchHint(modifier.padding(start = 24.dp, end = 8.dp))
}
Row(verticalAlignment = Alignment.CenterVertically) {
BasicTextField(
value = query,
onValueChange = onQueryChange,
modifier = Modifier
.fillMaxHeight()
.weight(1f)
.onFocusChanged {
onSearchFocusChange(it.isFocused)
}
.focusRequester(focusRequester)
.padding(top = 9.dp, bottom = 8.dp, start = 24.dp, end = 8.dp),
singleLine = true
)
when {
searching -> {
CircularProgressIndicator(
modifier = Modifier
.padding(horizontal = 6.dp)
.size(36.dp)
)
}
query.text.isNotEmpty() -> {
IconButton(onClick = onClearQuery) {
Icon(imageVector = Icons.Filled.Cancel, contentDescription = null)
}
}
}
}
}
}
}
}
您可以删除CircularProgressBar或将图标添加到包含BasicTextField
Row
使用上面的SearchTextField和返回功能的返回箭头6-SearchBar。AnimatedVisibility确保在SearchTextField中聚焦BasicTextField时箭头是动画的，它还可以与Icon一起用作放大镜。
@ExperimentalAnimationApi
@OptIn(ExperimentalComposeUiApi::class)
@Composable
fun SearchBar(
query: TextFieldValue,
onQueryChange: (TextFieldValue) -> Unit,
onSearchFocusChange: (Boolean) -> Unit,
onClearQuery: () -> Unit,
onBack: ()-> Unit,
searching: Boolean,
focused: Boolean,
modifier: Modifier = Modifier
) {
val focusManager = LocalFocusManager.current
val keyboardController = LocalSoftwareKeyboardController.current
Row(
modifier = modifier.fillMaxWidth(),
verticalAlignment = Alignment.CenterVertically
) {
AnimatedVisibility(visible = focused) {
// Back button
IconButton(
modifier = Modifier.padding(start =2.dp),
onClick = {
focusManager.clearFocus()
keyboardController?.hide()
onBack()
}) {
Icon(imageVector = Icons.Default.ArrowBack, contentDescription = null)
}
}
SearchTextField(
query,
onQueryChange,
onSearchFocusChange,
onClearQuery,
searching,
focused,
modifier.weight(1f)
)
}
}
SearchState进行更新
在ViewModel中使用LaunchedEffect或设置muableState可以设置查询结果或searching显示加载的状态字段
fun HomeScreen(
modifier: Modifier = Modifier,
viewModel: HomeViewModel,
navigateToTutorial: (String) -> Unit,
state: SearchState = rememberSearchState()
) {
Column(
modifier = modifier.fillMaxSize()
) {
SearchBar(
query = state.query,
onQueryChange = { state.query = it },
onSearchFocusChange = { state.focused = it },
onClearQuery = { state.query = TextFieldValue("") },
onBack = { state.query = TextFieldValue("") },
searching = state.searching,
focused = state.focused,
modifier = modifier
)
LaunchedEffect(state.query.text) {
state.searching = true
delay(100)
state.searchResults = viewModel.getTutorials(state.query.text)
state.searching = false
}
when (state.searchDisplay) {
SearchDisplay.InitialResults -> {
}
SearchDisplay.NoResults -> {
}
SearchDisplay.Suggestions -> {
}
SearchDisplay.Results -> {
}
}
}
}
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