CollapsingTopBarCompose

A Jetpack Compose TopBar that collapses or expands based on detected scroll events or by calling: CollapsingTopBarScrollBehavior.collapse() or CollapsingTopBarScrollBehavior.expand() extension methods.

Collapse/Expand due to user scroll and/or by calling the methods: collapse() & expand()	Collapse/Expand due to user scroll while displaying only the title on the left side	Expand only when a user has reached the top of a LazyColumn

How to get this library in your android app

Step 1. Add the jitpack repository to the repositories { } function, inside your project build.gradle or inside your settings.gradle like so:

repositories {
    google()
    mavenCentral()
    // Place the jitpack repository inside this, like so:
    maven { url 'https://jitpack.io' }
}

Step 2. Add the dependency in your module build.gradle file, like so:

dependencies {
    implementation "com.github.germainkevinbusiness:CollapsingTopBarCompose:1.2.3"
}

How to use this library

1 - In order to use a CollapsingTopBar, you first need to create a CollapsingTopBarScrollBehavior.

val scrollBehavior = rememberCollapsingTopBarScrollBehavior(
    isAlwaysCollapsed = false,
    isExpandedWhenFirstDisplayed = true,
    centeredTitleWhenCollapsed = false,
    centeredTitleAndSubtitle = true,
    collapsedTopBarHeight = 56.dp,
    expandedTopBarMaxHeight = 156.dp,
    scrollableState = null
)

2- In order for the CollapsingTopBar to collapse or expand when a vertical scrolling is occuring inside your Layout, you need to add the scrollBehavior.nestedScrollConnection inside your Layout's Modifier.nestedScroll :

 Scaffold(
        modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
        topBar = {
            CollapsingTopBar(
                scrollBehavior = scrollBehavior,
                title = { Text(text = "Contacts") },
                subtitle = { Text(text = "17 contacts") },
                mainAction = {
                    IconButton(onClick = {}) {
                        Icon(
                            Icons.Outlined.Add,
                            contentDescription = "Main Action Icon",
                        )
                    }
                },
            )
        },
    ) {
        Column(modifier = Modifier.verticalScroll(rememberScrollState())) {}
        
        Column(modifier = Modifier.verticalScroll(rememberScrollState())) {}
    }

So a complete example could look like:

Column(modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection)) {
    CollapsingTopBar(
        scrollBehavior = scrollBehavior,
        title = { TitleText },
        expandedTitle = { ExpandedTitleText },
        subtitle = { SubtitleText },
        navigationIcon = { NavigationIcon },
        mainAction = { MainActionIconButton },
        actions = { MoreMenuIcons },
    )
    LazyColumn {
        items(contactsList) {
            Row(
                modifier = Modifier.fillMaxWidth().clickable { },
            ) {
                Text( modifier = Modifier.padding(16.dp), text = it )
            }
        }
    }
}

The above example is when you want the CollapsingTopBar to collapse or expand on any detected vertical scroll.
But what if for example, you want your CollapsingTopBar to only expand when a user is at the top of your LazyColumn or LazyVerticalGrid? For that, you need to pass a ScrollableState such as a LazyListState for a LazyColumn or a LazyGridState for a LazyVerticalGrid, inside your CollapsingTopBarScrollBehavior:

val scrollableState = rememberLazyListState()
val scrollBehavior = rememberCollapsingTopBarScrollBehavior(
    isAlwaysCollapsed = false,
    isExpandedWhenFirstDisplayed = true,
    centeredTitleWhenCollapsed = false,
    centeredTitleAndSubtitle = true,
    collapsedTopBarHeight = 56.dp,
    expandedTopBarMaxHeight = 156.dp,
    scrollableState = scrollableState
)

Then you pass that same ScrollableState to your LazyColumn, like so:

Column(modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection)) {
    CollapsingTopBar(
        scrollBehavior = scrollBehavior,
        title = { TitleText },
        expandedTitle = { ExpandedTitleText },
        subtitle = { SubtitleText },
        navigationIcon = { NavigationIcon },
        mainAction = { MainActionIconButton },
        actions = { MoreMenuIcons },
    )
    LazyColumn(state = scrollableState) {
        items(contactsList) {
            Row(
                modifier = Modifier.fillMaxWidth().clickable { },
            ) {
                Text( modifier = Modifier.padding(16.dp), text = it )
            }
        }
    }
}

The above examples are basic examples, to know & learn more about the CollapsingTopBar, check out the sample app .

License

Licenced under the MIT Licence

Copyright (c) 2023 Kevin Germain

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Author & support

This project was created by Germain Kevin.

If this project help you reduce time to develop, you can give me a cup of coffee :)