perf(Android): recycle replaced shadow bitmaps

android/src/main/java/com/reactnativenavigation/views/bottomtabs/ShadowLayout.kt

@@ -36,8 +36,8 @@ open class ShadowLayout(context: Context) : FrameLayout(context) {
 
     override fun onDetachedFromWindow() {
         super.onDetachedFromWindow()
-        bitmap?.recycle()
-        bitmap = null
+        recycleShadowBitmap()
+        invalidateShadow = true
     }
 
     var isShadowed: Boolean = false
@@ -108,6 +108,7 @@ open class ShadowLayout(context: Context) : FrameLayout(context) {
         if (isShadowed) {
             if (invalidateShadow) {
                 if (bounds.width() != 0 && bounds.height() != 0) {
+                    recycleShadowBitmap()
                     bitmap = Bitmap.createBitmap(bounds.width(), bounds.height(), Bitmap.Config.ARGB_8888).also {
                         mainCanvas.setBitmap(it)
                         invalidateShadow = false
@@ -132,4 +133,10 @@ open class ShadowLayout(context: Context) : FrameLayout(context) {
 
         super.dispatchDraw(canvas)
     }
+
+    private fun recycleShadowBitmap() {
+        mainCanvas.setBitmap(null)
+        bitmap?.recycle()
+        bitmap = null
+    }
 }

android/src/test/java/com/reactnativenavigation/views/bottomtabs/ShadowLayoutTest.kt

@@ -0,0 +1,41 @@
+package com.reactnativenavigation.views.bottomtabs
+
+import android.graphics.Bitmap
+import android.graphics.Canvas
+import android.view.View
+import com.reactnativenavigation.BaseTest
+import org.junit.Assert.assertNotSame
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class ShadowLayoutTest : BaseTest() {
+    @Test
+    fun regeneratingShadowRecyclesPreviousBitmap() {
+        val view = ShadowLayout(newActivity()).apply { isShadowed = true }
+        val output = Bitmap.createBitmap(40, 40, Bitmap.Config.ARGB_8888)
+
+        measureAndDraw(view, output)
+        val firstShadow = shadowBitmap(view)
+
+        view.requestLayout()
+        measureAndDraw(view, output)
+        val secondShadow = shadowBitmap(view)
+
+        assertNotSame(firstShadow, secondShadow)
+        assertTrue(firstShadow.isRecycled)
+        output.recycle()
+    }
+
+    private fun measureAndDraw(view: ShadowLayout, output: Bitmap) {
+        val size = View.MeasureSpec.makeMeasureSpec(40, View.MeasureSpec.EXACTLY)
+        view.measure(size, size)
+        view.layout(0, 0, 40, 40)
+        view.draw(Canvas(output))
+    }
+
+    private fun shadowBitmap(view: ShadowLayout): Bitmap {
+        val field = ShadowLayout::class.java.getDeclaredField("bitmap")
+        field.isAccessible = true
+        return field.get(view) as Bitmap
+    }
+}