Merge pull request #1480 from fansangg/fix/read-nav-height

fix：阅读界面切换深浅色，底部菜单高度抖动的问题

app/src/main/java/io/legado/app/ui/book/read/ReadBookMenuBar.kt

@@ -6,10 +6,8 @@ import androidx.compose.animation.AnimatedContent
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.SizeTransform
 import androidx.compose.animation.animateContentSize
-import androidx.compose.animation.core.LinearOutSlowInEasing
 import androidx.compose.animation.core.animateDpAsState
 import androidx.compose.animation.core.animateFloatAsState
-import androidx.compose.animation.core.tween
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
 import androidx.compose.animation.slideInHorizontally
@@ -79,6 +77,7 @@ import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
@@ -101,6 +100,7 @@ import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.layout.layout
 import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.LocalLayoutDirection
@@ -411,7 +411,13 @@ private fun ReadBookMenuSurface(
         560.dp
     }
     val isFloating = state.menuConfig.readMenuFloatingBottomBar
-    val navBarHeight = with(density) { WindowInsets.navigationBars.getBottom(this).toDp() }
+    val orientation = LocalConfiguration.current.orientation
+    val currentNavBarHeight = with(density) { WindowInsets.navigationBars.getBottom(this).toDp() }
+    var lastValidNavBarHeightValue by rememberSaveable(orientation) { mutableFloatStateOf(currentNavBarHeight.value) }
+    if (currentNavBarHeight.value > 0f && lastValidNavBarHeightValue != currentNavBarHeight.value) {
+        lastValidNavBarHeightValue = currentNavBarHeight.value
+    }
+    val navBarHeight = if (currentNavBarHeight.value > 0f) currentNavBarHeight else lastValidNavBarHeightValue.dp
     val floatingHorizontalMargin = if (isFloating) 16.dp else 0.dp
     val floatingBottomMargin = if (isFloating) 16.dp + navBarHeight else 0.dp
     val mainHorizontalMargin =