Merge 3c7e485659 into e846078f9d

core/designsystem/src/main/kotlin/com/google/samples/apps/nowinandroid/core/designsystem/component/scrollbar/LazyScrollbarUtilities.kt

@@ -74,6 +74,19 @@ internal fun itemVisibilityPercentage(
     viewportEndOffset: Int,
 ): Float {
     if (itemSize == 0) return 0f
+    // TODO: Workaround due to issue b/353143657, monitor if compose team will agree it's an issue
+    //  and fix it, if so, below safeguard probably can be removed
+    if (
+        isItemOutOfViewport(
+            itemSize = itemSize,
+            itemStartOffset = itemStartOffset,
+            viewportStartOffset = viewportStartOffset,
+            viewportEndOffset = viewportEndOffset,
+        )
+    ) {
+        return 0f
+    }
+
     val itemEnd = itemStartOffset + itemSize
     val startOffset = when {
         itemStartOffset > viewportStartOffset -> 0
@@ -86,3 +99,28 @@ internal fun itemVisibilityPercentage(
     val size = itemSize.toFloat()
     return (size - startOffset - endOffset) / size
 }
+
+private fun isItemOutOfViewport(
+    itemSize: Int,
+    itemStartOffset: Int,
+    viewportStartOffset: Int,
+    viewportEndOffset: Int,
+) = isItemBeforeViewport(
+    itemSize = itemSize,
+    itemStartOffset = itemStartOffset,
+    viewportStartOffset = viewportStartOffset,
+) || isItemAfterViewport(
+    itemStartOffset = itemStartOffset,
+    viewportEndOffset = viewportEndOffset,
+)
+
+private fun isItemBeforeViewport(
+    itemSize: Int,
+    itemStartOffset: Int,
+    viewportStartOffset: Int,
+) = (viewportStartOffset - itemStartOffset) > itemSize
+
+private fun isItemAfterViewport(
+    itemStartOffset: Int,
+    viewportEndOffset: Int,
+) = itemStartOffset > viewportEndOffset

core/designsystem/src/main/kotlin/com/google/samples/apps/nowinandroid/core/designsystem/component/scrollbar/ScrollbarExt.kt

@@ -115,7 +115,10 @@ fun LazyGridState.scrollbarState(
 
             val firstIndex = min(
                 a = interpolateFirstItemIndex(
-                    visibleItems = visibleItemsInfo,
+                    visibleItems = when (layoutInfo.orientation) {
+                        Orientation.Vertical -> layoutInfo.visibleItemsInfo.filter { it.row == 0 }
+                        Orientation.Horizontal -> layoutInfo.visibleItemsInfo.filter { it.column == 0 }
+                    },
                     itemSize = { layoutInfo.orientation.valueOf(it.size) },
                     offset = { layoutInfo.orientation.valueOf(it.offset) },
                     nextItemOnMainAxis = { first ->
@@ -189,7 +192,7 @@ fun LazyStaggeredGridState.scrollbarState(
 
             val firstIndex = min(
                 a = interpolateFirstItemIndex(
-                    visibleItems = visibleItemsInfo,
+                    visibleItems = layoutInfo.visibleItemsInfo.filter { it.lane == 0 },
                     itemSize = { layoutInfo.orientation.valueOf(it.size) },
                     offset = { layoutInfo.orientation.valueOf(it.offset) },
                     nextItemOnMainAxis = { first ->