fix(Android, Stack): incorrect header height values

android/src/main/java/com/swmansion/rnscreens/Screen.kt

@@ -34,6 +34,7 @@ import com.swmansion.rnscreens.events.SheetDetentChangedEvent
 import com.swmansion.rnscreens.ext.asScreenStackFragment
 import com.swmansion.rnscreens.ext.parentAsViewGroup
 import com.swmansion.rnscreens.gamma.common.FragmentProviding
+import com.swmansion.rnscreens.utils.pxToDp
 import kotlin.math.max
 
 @SuppressLint("ViewConstructor") // Only we construct this view, it is never inflated.
@@ -185,9 +186,6 @@ class Screen(
             val height = b - t
 
             dispatchShadowStateUpdate(width, height, t)
-
-            // FormSheet has no header in current model.
-            notifyHeaderHeightChange(t)
         }
     }
 
@@ -456,12 +454,18 @@ class Screen(
             super.onTouchEvent(event)
         }
 
-    private fun notifyHeaderHeightChange(headerHeight: Int) {
+    fun notifyHeaderHeightChange(headerHeight: Int) {
         val screenContext = context as ReactContext
         val surfaceId = UIManagerHelper.getSurfaceId(screenContext)
         UIManagerHelper
             .getEventDispatcherForReactTag(screenContext, id)
-            ?.dispatchEvent(HeaderHeightChangeEvent(surfaceId, id, headerHeight))
+            ?.dispatchEvent(
+                HeaderHeightChangeEvent(
+                    surfaceId,
+                    id,
+                    pxToDp(screenContext, headerHeight.toFloat()).toDouble(),
+                ),
+            )
     }
 
     internal fun onSheetDetentChanged(

android/src/main/java/com/swmansion/rnscreens/ScreenStackHeaderConfig.kt

@@ -93,6 +93,8 @@ class ScreenStackHeaderConfig(
                 defaultStartInsetWithNavigation
             }
 
+    val headerHeightUpdateProxy = ScreenStackHeaderHeightUpdateProxy(this)
+
     fun destroy() {
         isDestroyed = true
     }
@@ -126,6 +128,8 @@ class ScreenStackHeaderConfig(
 
         val contentInsetEnd = toolbar.currentContentInsetEnd + toolbar.paddingEnd
 
+        headerHeightUpdateProxy.updateHeaderHeightIfNeeded()
+
         // Note that implementation of the callee differs between architectures.
         updateHeaderConfigState(
             toolbar.width,
@@ -162,7 +166,7 @@ class ScreenStackHeaderConfig(
             ?.dispatchEvent(HeaderDetachedEvent(surfaceId, id))
     }
 
-    private val screen: Screen?
+    val screen: Screen?
         get() = parent as? Screen
 
     private val screenStack: ScreenStack?
@@ -216,6 +220,7 @@ class ScreenStackHeaderConfig(
             if (toolbar.parent != null) {
                 screenFragment?.removeToolbar()
             }
+            headerHeightUpdateProxy.updateHeaderHeightIfNeeded()
             return
         }
 
@@ -336,6 +341,8 @@ class ScreenStackHeaderConfig(
             toolbar.addView(view)
             i++
         }
+
+        headerHeightUpdateProxy.updateHeaderHeightIfNeeded()
     }
 
     private fun maybeUpdate() {

android/src/main/java/com/swmansion/rnscreens/ScreenStackHeaderHeightUpdateProxy.kt

@@ -0,0 +1,16 @@
+package com.swmansion.rnscreens
+
+class ScreenStackHeaderHeightUpdateProxy(
+    val config: ScreenStackHeaderConfig,
+) {
+    var previousHeaderHeightInPx: Int? = null
+
+    fun updateHeaderHeightIfNeeded() {
+        val currentHeaderHeightInPx = if (config.isHeaderHidden) 0 else config.toolbar.height
+
+        if (currentHeaderHeightInPx != previousHeaderHeightInPx) {
+            previousHeaderHeightInPx = currentHeaderHeightInPx
+            config.screen?.notifyHeaderHeightChange(currentHeaderHeightInPx)
+        }
+    }
+}

android/src/main/java/com/swmansion/rnscreens/events/HeaderHeightChangeEvent.kt

@@ -7,16 +7,16 @@ import com.facebook.react.uimanager.events.Event
 class HeaderHeightChangeEvent(
     surfaceId: Int,
     viewId: Int,
-    private val headerHeight: Int,
+    private val headerHeightInDp: Double,
 ) : Event<HeaderHeightChangeEvent>(surfaceId, viewId) {
     override fun getEventName() = EVENT_NAME
 
     // As the same header height could appear twice, use header height as a coalescing key.
-    override fun getCoalescingKey(): Short = headerHeight.toShort()
+    override fun getCoalescingKey(): Short = headerHeightInDp.toInt().toShort()
 
     override fun getEventData(): WritableMap? =
         Arguments.createMap().apply {
-            putDouble("headerHeight", headerHeight.toDouble())
+            putDouble("headerHeight", headerHeightInDp)
         }
 
     companion object {

android/src/main/java/com/swmansion/rnscreens/utils/DimensionUtils.kt

@@ -0,0 +1,21 @@
+package com.swmansion.rnscreens.utils
+
+import android.content.Context
+import android.os.Build
+import android.util.TypedValue
+
+fun pxToDp(
+    context: Context,
+    px: Float,
+): Float {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
+        return TypedValue.deriveDimension(
+            TypedValue.COMPLEX_UNIT_DIP,
+            px,
+            context.resources.displayMetrics,
+        )
+    } else {
+        val density = context.resources.displayMetrics.density
+        return px / density
+    }
+}