use web scroll changes to change top app bar height

android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/reader/WebReader.kt

@@ -67,6 +67,11 @@ fun WebReader(
         settings.domStorageEnabled = true
 
         webViewClient = object : WebViewClient() {
+          override fun onPageFinished(view: WebView?, url: String?) {
+            super.onPageFinished(view, url)
+            // Add padding to top so TopAppBar doesn't cover content
+            view?.loadUrl("javascript:(function(){ document.body.style.paddingTop = '48px'})();");
+          }
         }
 
         val javascriptInterface = AndroidWebKitMessenger { actionID, json ->
@@ -219,10 +224,9 @@ class OmnivoreWebView(context: Context) : WebView(context), OnScrollChangeListen
       Log.d("wv", "outRect: $outRect, View: $view")
       if (viewModel?.lastTapCoordinates != null) {
         val xValue = viewModel!!.lastTapCoordinates!!.tapX.toInt()
-        val yValue = viewModel!!.lastTapCoordinates!!.tapY.toInt() + (viewModel?.currentToolbarHeight ?: 0)
+        val yValue = viewModel!!.lastTapCoordinates!!.tapY.toInt()
         val rect = Rect(xValue, yValue, xValue, yValue)
 
-        Log.d("wvt", "bar height: ${viewModel?.currentToolbarHeight}")
         Log.d("wvt", "setting rect based on last tapped rect: ${viewModel?.lastTapCoordinates.toString()}")
         Log.d("wvt", "rect: $rect")
 
@@ -253,6 +257,7 @@ class OmnivoreWebView(context: Context) : WebView(context), OnScrollChangeListen
 
   override fun onScrollChange(view: View?, x: Int, y: Int, oldX: Int, oldY: Int) {
     viewModel?.scrollY = y
+    viewModel?.onScrollChange((oldY - y).toFloat())
   }
 }
 

android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/reader/WebReaderLoadingContainer.kt

@@ -36,6 +36,7 @@ import androidx.compose.ui.unit.dp
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsCompat
+import androidx.lifecycle.viewmodel.compose.viewModel
 import app.omnivore.omnivore.MainActivity
 import app.omnivore.omnivore.ui.savedItemViews.SavedItemContextMenu
 import app.omnivore.omnivore.ui.theme.OmnivoreTheme
@@ -111,24 +112,12 @@ fun WebReaderLoadingContainer(slug: String? = null, requestID: String? = null, o
   val webReaderParams: WebReaderParams? by webReaderViewModel.webReaderParamsLiveData.observeAsState(null)
   val annotation: String? by webReaderViewModel.annotationLiveData.observeAsState(null)
   val shouldPopView: Boolean by webReaderViewModel.shouldPopViewLiveData.observeAsState(false)
+  val toolbarHeightPx: Float by webReaderViewModel.currentToolbarHeightLiveData.observeAsState(0.0f)
 
   val maxToolbarHeight = 48.dp
-  val maxToolbarHeightPx = with(LocalDensity.current) { maxToolbarHeight.roundToPx().toFloat() }
-  val toolbarHeightPx = remember { mutableStateOf(maxToolbarHeightPx) }
-
-  // Create a connection to the nested scroll system and listen to the scroll happening inside child Column
-  val nestedScrollConnection = remember {
-    object : NestedScrollConnection {
-      override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
-        val delta = available.y
-        val newHeight = toolbarHeightPx.value + delta
-        toolbarHeightPx.value = newHeight.coerceIn(0f, maxToolbarHeightPx)
-        return Offset.Zero
-      }
-    }
-  }
 
   if (webReaderParams == null) {
+    webReaderViewModel.maxToolbarHeightPx = with(LocalDensity.current) { maxToolbarHeight.roundToPx().toFloat() }
     webReaderViewModel.loadItem(slug = slug, requestID = requestID)
   }
 
@@ -136,27 +125,14 @@ fun WebReaderLoadingContainer(slug: String? = null, requestID: String? = null, o
     Box(
       modifier = Modifier
         .fillMaxSize()
-        .nestedScroll(nestedScrollConnection)
     ) {
-      Column(
-        modifier = Modifier
-          .fillMaxSize()
-      ) {
-        Row(
-          modifier = Modifier
-            .fillMaxWidth()
-            .requiredHeight(height = maxToolbarHeight)
-        ) {
-        }
         WebReader(webReaderParams!!, webReaderViewModel.storedWebPreferences(isSystemInDarkTheme()), webReaderViewModel)
-      }
 
       TopAppBar(
         modifier = Modifier
           .height(height = with(LocalDensity.current) {
-            webReaderViewModel.currentToolbarHeight = toolbarHeightPx.value.toInt()
-            toolbarHeightPx.value.roundToInt().toDp()
-          } ),
+            toolbarHeightPx.roundToInt().toDp()
+          }),
         backgroundColor = MaterialTheme.colorScheme.surfaceVariant,
         title = {},
         actions = {

android/Omnivore/app/src/main/java/app/omnivore/omnivore/ui/reader/WebReaderViewModel.kt

@@ -2,6 +2,10 @@ package app.omnivore.omnivore.ui.reader
 
 import android.util.Log
 import androidx.compose.foundation.ScrollState
+import androidx.compose.runtime.remember
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
+import androidx.compose.ui.input.nestedscroll.NestedScrollSource
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -35,13 +39,14 @@ class WebReaderViewModel @Inject constructor(
   var lastJavascriptActionLoopUUID: UUID = UUID.randomUUID()
   var javascriptDispatchQueue: MutableList<String> = mutableListOf()
   var scrollY = 0
-  var currentToolbarHeight = 0
+  var maxToolbarHeightPx = 0.0f
 
   val webReaderParamsLiveData = MutableLiveData<WebReaderParams?>(null)
   val annotationLiveData = MutableLiveData<String?>(null)
   val javascriptActionLoopUUIDLiveData = MutableLiveData(lastJavascriptActionLoopUUID)
-  val shouldPopViewLiveData = MutableLiveData<Boolean>(false)
-  val hasFetchError = MutableLiveData<Boolean>(false)
+  val shouldPopViewLiveData = MutableLiveData(false)
+  val hasFetchError = MutableLiveData(false)
+  val currentToolbarHeightLiveData = MutableLiveData(0.0f)
 
   var hasTappedExistingHighlight = false
   var lastTapCoordinates: TapCoordinates? = null
@@ -53,6 +58,11 @@ class WebReaderViewModel @Inject constructor(
     }
   }
 
+  fun onScrollChange(delta: Float) {
+    val newHeight = (currentToolbarHeightLiveData.value ?: 0.0f) + delta
+    currentToolbarHeightLiveData.value = newHeight.coerceIn(0f, maxToolbarHeightPx)
+  }
+
   private suspend fun loadItemUsingSlug(slug: String) {
     val webReaderParams = loadItemFromServer(slug)