feat(common-ui): connect scroll view inside web view to top bar (#15)

core-commonui/src/androidMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/commonui/components/CustomWebView.kt

@@ -8,6 +8,10 @@ import android.webkit.WebViewClient
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
+import androidx.compose.ui.input.nestedscroll.NestedScrollSource
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.viewinterop.AndroidView
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
@@ -15,9 +19,10 @@ import kotlinx.coroutines.flow.onEach
 @SuppressLint("SetJavaScriptEnabled")
 @Composable
 actual fun CustomWebView(
-    navigator: WebViewNavigator,
-    modifier: Modifier,
     url: String,
+    modifier: Modifier,
+    navigator: WebViewNavigator,
+    scrollConnection: NestedScrollConnection?,
 ) {
     var webView: WebView? = null
 
@@ -29,6 +34,7 @@ actual fun CustomWebView(
         }.launchIn(this)
     }
 
+    val density = LocalDensity.current.density
     AndroidView(
         modifier = modifier,
         factory = { context ->
@@ -44,7 +50,17 @@ actual fun CustomWebView(
                 }
                 settings.javaScriptEnabled = true
 
+                setOnScrollChangeListener { _, scrollX, scrollY, oldScrollX, oldScrollY ->
+                    scrollConnection?.onPreScroll(
+                        available = Offset(
+                            x = (oldScrollX - scrollX) / density,
+                            y = (oldScrollY - scrollY) / density,
+                        ), source = NestedScrollSource.Drag
+                    )
+                }
+
                 loadUrl(url)
+
                 webView = this
             }
         },

core-commonui/src/commonMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/commonui/components/CustomWebView.kt

@@ -2,10 +2,12 @@ package com.github.diegoberaldin.raccoonforlemmy.core.commonui.components
 
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
 
 @Composable
 expect fun CustomWebView(
-    navigator: WebViewNavigator = rememberWebViewNavigator(),
-    modifier: Modifier = Modifier,
     url: String,
+    modifier: Modifier = Modifier,
+    navigator: WebViewNavigator = rememberWebViewNavigator(),
+    scrollConnection: NestedScrollConnection? = null,
 )

core-commonui/src/commonMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/commonui/web/WebViewScreen.kt

@@ -10,6 +10,7 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.remember
@@ -28,10 +29,12 @@ class WebViewScreen(
     @Composable
     override fun Content() {
         val navigator = remember { getNavigationCoordinator().getRootNavigator() }
+        val scrollBehavior = TopAppBarDefaults.enterAlwaysScrollBehavior()
         Scaffold(
             topBar = {
                 TopAppBar(
                     title = {},
+                    scrollBehavior = scrollBehavior,
                     navigationIcon = {
                         Image(
                             modifier = Modifier.onClick {
@@ -68,6 +71,7 @@ class WebViewScreen(
                 CustomWebView(
                     modifier = Modifier.fillMaxSize(),
                     navigator = webNavigator,
+                    scrollConnection = scrollBehavior.nestedScrollConnection,
                     url = url,
                 )
             }

core-commonui/src/iosMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/commonui/components/CustomWebView.kt

@@ -2,12 +2,23 @@ package com.github.diegoberaldin.raccoonforlemmy.core.commonui.components
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
+import androidx.compose.ui.input.nestedscroll.NestedScrollSource
 import androidx.compose.ui.interop.UIKitView
+import androidx.compose.ui.platform.LocalDensity
 import kotlinx.cinterop.readValue
+import kotlinx.cinterop.useContents
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import platform.CoreGraphics.CGRectZero
+import platform.UIKit.UIScrollView
+import platform.UIKit.UIScrollViewDelegateProtocol
 import platform.WebKit.WKNavigation
 import platform.WebKit.WKNavigationDelegateProtocol
 import platform.WebKit.WKWebView
@@ -16,9 +27,10 @@ import platform.darwin.NSObject
 
 @Composable
 actual fun CustomWebView(
-    navigator: WebViewNavigator,
-    modifier: Modifier,
     url: String,
+    modifier: Modifier,
+    navigator: WebViewNavigator,
+    scrollConnection: NestedScrollConnection?,
 ) {
     var webView: WKWebView? = null
 
@@ -30,6 +42,10 @@ actual fun CustomWebView(
         }.launchIn(this)
     }
 
+    val density = LocalDensity.current.density
+    var lastOffsetX by remember { mutableStateOf(0f) }
+    var lastOffsetY by remember { mutableStateOf(0f) }
+
     UIKitView(
         factory = {
             val config = WKWebViewConfiguration().apply {
@@ -42,7 +58,6 @@ actual fun CustomWebView(
                 userInteractionEnabled = true
                 allowsBackForwardNavigationGestures = true
                 val navigationDelegate = object : NSObject(), WKNavigationDelegateProtocol {
-
                     override fun webView(
                         webView: WKWebView,
                         didFinishNavigation: WKNavigation?,
@@ -51,6 +66,21 @@ actual fun CustomWebView(
                     }
                 }
                 this.navigationDelegate = navigationDelegate
+                this.scrollView.delegate = object : NSObject(), UIScrollViewDelegateProtocol {
+                    override fun scrollViewDidScroll(scrollView: UIScrollView) {
+                        scrollView.contentOffset.useContents {
+                            val offsetX = (lastOffsetX - x).toFloat() / density
+                            val offsetY = (lastOffsetY - y).toFloat() / density
+                            scrollConnection?.onPreScroll(
+                                available = Offset(offsetX, offsetY),
+                                source = NestedScrollSource.Drag,
+                            )
+                            lastOffsetX = x.toFloat()
+                            lastOffsetY = y.toFloat()
+                        }
+                    }
+                }
+
             }.also {
                 webView = it
             }