Desktop support

.editorconfig

@@ -39,6 +39,7 @@ ij_kotlin_code_style_defaults = KOTLIN_OFFICIAL
 
 # https://youtrack.jetbrains.com/issue/KTIJ-17907
 ij_continuation_indent_size = 4
+ij_kotlin_indent_before_arrow_on_new_line = true
 
 # Trailing comma
 ij_kotlin_allow_trailing_comma_on_call_site = true

.run/Run Desktop App.run.xml

@@ -0,0 +1,27 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Run Desktop App" type="GradleRunConfiguration" factoryName="Gradle">
+    <ExternalSystemSettings>
+      <option name="executionName" />
+      <option name="externalProjectPath" value="$PROJECT_DIR$/sample/desktop" />
+      <option name="externalSystemIdString" value="GRADLE" />
+      <option name="scriptParameters" value="-DmainClass=com.flaringapp.compose.topbar.sample.desktop.MainKt --quiet" />
+      <option name="taskDescriptions">
+        <list />
+      </option>
+      <option name="taskNames">
+        <list>
+          <option value="run" />
+        </list>
+      </option>
+      <option name="vmOptions" />
+    </ExternalSystemSettings>
+    <ExternalSystemDebugServerProcess>false</ExternalSystemDebugServerProcess>
+    <ExternalSystemReattachDebugProcess>true</ExternalSystemReattachDebugProcess>
+    <ExternalSystemDebugDisabled>false</ExternalSystemDebugDisabled>
+    <DebugAllEnabled>false</DebugAllEnabled>
+    <RunAsTest>false</RunAsTest>
+    <GradleProfilingDisabled>false</GradleProfilingDisabled>
+    <GradleCoverageDisabled>false</GradleCoverageDisabled>
+    <method v="2" />
+  </configuration>
+</component>

ComposeCollapsingTopBar/build.gradle.kts

@@ -46,6 +46,8 @@ kotlin {
         }
     }
 
+    jvm()
+
     sourceSets {
         commonMain.dependencies {
             implementation(libs.compose.multiplatform.foundation)

README.md

@@ -10,6 +10,7 @@
 
 ![badge-Android](https://img.shields.io/badge/Platform-Android-forestgreen)
 ![badge-iOS](https://img.shields.io/badge/Platform-iOS-silver)
+![badge-Desktop](https://img.shields.io/badge/Platform-Desktop-dodgerblue)
 
 If you like this project, :star: star and :loudspeaker: share it!
 
@@ -739,8 +740,16 @@ This state exposes current exit offset via `exitHeight`.
 
 ## More examples
 
-Feel free to install a demo [Android](/sample/android) or [iOS](/sample/ios) app and try yourself
-even more samples!
+Feel free to install a demo [Android](/sample/android), [iOS](/sample/ios), or
+[Desktop](/sample/desktop) app and try yourself even more samples!
+
+## Known issues
+
+- On Desktop, a Compose Multiplatform nested scroll bug can prevent the top bar from expanding
+  with mouse wheel scrolling when using scroll modes with `expandAlways = false`. See
+  [CMP-10236](https://youtrack.jetbrains.com/issue/CMP-10236). The sample app includes a
+  [temporary workaround](/sample/shared/src/jvmMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/desktopfix/DesktopScrollBoundsNestedScrollFix.jvm.kt)
+  that can be copied until Compose fixes the issue.
 
 ## Contributing
 

build.gradle.kts

@@ -4,6 +4,7 @@ import org.jlleitschuh.gradle.ktlint.KtlintExtension
 plugins {
     alias(libs.plugins.android.application) apply false
     alias(libs.plugins.android.kotlin.multiplatform.library) apply false
+    alias(libs.plugins.jetbrains.kotlin.jvm) apply false
     alias(libs.plugins.jetbrains.kotlin.multiplatform) apply false
     alias(libs.plugins.jetbrains.kotlin.compose) apply false
     alias(libs.plugins.jetbrains.compose.multiplatform) apply false

gradle/libs.versions.toml

@@ -21,6 +21,7 @@ slack-compose-linter = { group = "com.slack.lint.compose", name = "compose-lint-
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }
 android-kotlin-multiplatform-library = { id = "com.android.kotlin.multiplatform.library", version.ref = "agp" }
+jetbrains-kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 jetbrains-kotlin-multiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotlin" }
 jetbrains-kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 jetbrains-compose-multiplatform = { id = "org.jetbrains.compose", version.ref = "composeMultiplatform" }

sample/desktop/build.gradle.kts

@@ -0,0 +1,25 @@
+import org.jetbrains.compose.desktop.application.dsl.TargetFormat
+
+plugins {
+    alias(libs.plugins.jetbrains.kotlin.jvm)
+    alias(libs.plugins.jetbrains.kotlin.compose)
+    alias(libs.plugins.jetbrains.compose.multiplatform)
+}
+
+dependencies {
+    implementation(project(":sample:shared"))
+
+    implementation(compose.desktop.currentOs)
+}
+
+compose.desktop {
+    application {
+        mainClass = "com.flaringapp.compose.topbar.sample.desktop.MainKt"
+
+        nativeDistributions {
+            targetFormats(TargetFormat.Dmg, TargetFormat.Msi, TargetFormat.Deb)
+            packageName = "com.flaringapp.compose.topbar.sample.desktop"
+            packageVersion = "1.0.0"
+        }
+    }
+}

sample/desktop/src/main/kotlin/com/flaringapp/compose/topbar/sample/desktop/Main.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2026 Flaringapp
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.flaringapp.compose.topbar.sample.desktop
+
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import com.flaringapp.compose.topbar.sample.shared.App
+
+fun main() = application {
+    Window(
+        onCloseRequest = ::exitApplication,
+        title = "ComposeCollapsingTopBar",
+    ) {
+        App()
+    }
+}

sample/shared/build.gradle.kts

@@ -28,6 +28,8 @@ kotlin {
         }
     }
 
+    jvm()
+
     sourceSets {
         commonMain.dependencies {
             implementation(project(":ComposeCollapsingTopBar"))

sample/shared/src/androidMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/desktopfix/DesktopScrollBoundsNestedScrollFix.android.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2026 Flaringapp
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.flaringapp.compose.topbar.sample.shared.ui.samples.desktopfix
+
+import androidx.compose.ui.Modifier
+import com.flaringapp.compose.topbar.scaffold.CollapsingTopBarScaffoldState
+
+internal actual fun Modifier.desktopScrollBoundsNestedScrollFix(
+    state: CollapsingTopBarScaffoldState,
+    isContentAtTop: () -> Boolean,
+): Modifier = this

sample/shared/src/appleMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/desktopfix/DesktopScrollBoundsNestedScrollFix.apple.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2026 Flaringapp
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.flaringapp.compose.topbar.sample.shared.ui.samples.desktopfix
+
+import androidx.compose.ui.Modifier
+import com.flaringapp.compose.topbar.scaffold.CollapsingTopBarScaffoldState
+
+internal actual fun Modifier.desktopScrollBoundsNestedScrollFix(
+    state: CollapsingTopBarScaffoldState,
+    isContentAtTop: () -> Boolean,
+): Modifier = this

sample/shared/src/commonMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/basic/BasicScaffoldSample.kt

@@ -16,6 +16,7 @@
 
 package com.flaringapp.compose.topbar.sample.shared.ui.samples.basic
 
+import androidx.compose.foundation.rememberScrollState
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
@@ -29,9 +30,11 @@ import com.flaringapp.compose.topbar.sample.shared.ui.samples.CollapsingTopBarSa
 import com.flaringapp.compose.topbar.sample.shared.ui.samples.common.SampleContent
 import com.flaringapp.compose.topbar.sample.shared.ui.samples.common.SampleTopAppBar
 import com.flaringapp.compose.topbar.sample.shared.ui.samples.common.SampleTopBarImage
+import com.flaringapp.compose.topbar.sample.shared.ui.samples.desktopfix.desktopScrollBoundsNestedScrollFix
 import com.flaringapp.compose.topbar.sample.shared.ui.theme.ComposeCollapsingTopBarTheme
 import com.flaringapp.compose.topbar.scaffold.CollapsingTopBarScaffold
 import com.flaringapp.compose.topbar.scaffold.CollapsingTopBarScaffoldScrollMode
+import com.flaringapp.compose.topbar.scaffold.rememberCollapsingTopBarScaffoldState
 
 private const val SCRIM_START_FRACTION = 0.25f
 
@@ -42,8 +45,15 @@ fun BasicScaffoldSampleContent(
     scrollMode: CollapsingTopBarScaffoldScrollMode,
     modifier: Modifier = Modifier,
 ) {
+    val scaffoldState = rememberCollapsingTopBarScaffoldState()
+    val contentScrollState = rememberScrollState()
+
     CollapsingTopBarScaffold(
-        modifier = modifier,
+        modifier = modifier.desktopScrollBoundsNestedScrollFix(
+            state = scaffoldState,
+            isContentAtTop = { contentScrollState.value == 0 },
+        ),
+        state = scaffoldState,
         scrollMode = scrollMode,
         topBar = {
             var topBarColorProgress by remember { mutableFloatStateOf(1f) }
@@ -66,7 +76,9 @@ fun BasicScaffoldSampleContent(
             )
         },
         body = {
-            SampleContent()
+            SampleContent(
+                scrollState = contentScrollState,
+            )
         },
     )
 }

sample/shared/src/commonMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/common/SampleContent.kt

@@ -16,6 +16,7 @@
 
 package com.flaringapp.compose.topbar.sample.shared.ui.samples.common
 
+import androidx.compose.foundation.ScrollState
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.ColumnScope
@@ -39,12 +40,13 @@ import com.flaringapp.compose.topbar.sample.shared.ui.theme.ComposeCollapsingTop
 @Composable
 inline fun SampleContent(
     modifier: Modifier = Modifier,
+    scrollState: ScrollState = rememberScrollState(),
     before: ColumnScope.() -> Unit = {},
 ) {
     Column(
         modifier = modifier
             .fillMaxSize()
-            .verticalScroll(rememberScrollState()),
+            .verticalScroll(scrollState),
     ) {
         before()
 

sample/shared/src/commonMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/common/SampleTopBarImage.kt

@@ -17,6 +17,7 @@
 package com.flaringapp.compose.topbar.sample.shared.ui.samples.common
 
 import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
@@ -47,10 +48,12 @@ fun SampleTopBarImage(
     height: Dp = 300.dp,
 ) {
     Image(
-        modifier = modifier.height(height),
+        modifier = modifier
+            .fillMaxWidth()
+            .height(height),
         painter = painterResource(dog.imageRes),
         contentDescription = null,
-        contentScale = ContentScale.FillHeight,
+        contentScale = ContentScale.Crop,
     )
 }
 

sample/shared/src/commonMain/kotlin/com/flaringapp/compose/topbar/sample/shared/ui/samples/desktopfix/DesktopScrollBoundsNestedScrollFix.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2026 Flaringapp
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.flaringapp.compose.topbar.sample.shared.ui.samples.desktopfix
+
+import androidx.compose.ui.Modifier
+import com.flaringapp.compose.topbar.scaffold.CollapsingTopBarScaffoldState
+
+/**
+ * Sample-only workaround for CMP-10236.
+ *
+ * https://youtrack.jetbrains.com/issue/CMP-10236
+ *
+ * Compose Desktop can skip parent nested-scroll `onPostScroll` when scrollable content is already
+ * at its bounds. This modifier forwards that leftover wheel delta to the scaffold state until
+ * Compose handles the case upstream.
+ */
+internal expect fun Modifier.desktopScrollBoundsNestedScrollFix(
+    state: CollapsingTopBarScaffoldState,
+    isContentAtTop: () -> Boolean,
+): Modifier