[fenix] Prevent flash when navigating to home

app/src/main/java/org/mozilla/fenix/browser/BaseBrowserFragment.kt

@@ -320,6 +320,7 @@ abstract class BaseBrowserFragment :
             engineView = binding.engineView,
             homeViewModel = homeViewModel,
             customTabSessionId = customTabSessionId,
+            browserAnimator = browserAnimator,
             onTabCounterClicked = {
                 thumbnailsFeature.get()?.requestScreenshot()
                 findNavController().nav(

app/src/main/java/org/mozilla/fenix/browser/BrowserAnimator.kt

@@ -42,8 +42,14 @@ class BrowserAnimator(
     }
 
     /**
-     * Makes the swipeRefresh background a screenshot of the engineView in its current state.
+     * Captures a screenshot of the current web page and sets the bitmap
-     * This allows us to "animate" the engineView.
+     * as a background of the engine view's parent (the swipeRefresh view).
+     *
+     * This is a workaround to prevent the home screen from flashing behind
+     * the browser fragment when navigating away. We've also found this to
+     * make transitions from the browser fragment to the home fragment
+     * smoother. So, in addition, we are currently also using it as a
+     * workaround to prevent flashes during those navigations.
      */
     fun captureEngineViewAndDrawStatically(onComplete: () -> Unit) {
         unwrappedEngineView?.asView()?.context.let {

app/src/main/java/org/mozilla/fenix/components/toolbar/BrowserToolbarController.kt

@@ -18,6 +18,7 @@ import mozilla.components.ui.tabcounter.TabCounterMenu
 import org.mozilla.fenix.FeatureFlags
 import org.mozilla.fenix.HomeActivity
 import org.mozilla.fenix.R
+import org.mozilla.fenix.browser.BrowserAnimator
 import org.mozilla.fenix.browser.BrowserAnimator.Companion.getToolbarNavOptions
 import org.mozilla.fenix.browser.BrowserFragmentDirections
 import org.mozilla.fenix.browser.browsingmode.BrowsingMode
@@ -58,6 +59,7 @@ class DefaultBrowserToolbarController(
     private val engineView: EngineView,
     private val homeViewModel: HomeScreenViewModel,
     private val customTabSessionId: String?,
+    private val browserAnimator: BrowserAnimator,
     private val onTabCounterClicked: () -> Unit,
     private val onCloseTab: (SessionState) -> Unit
 ) : BrowserToolbarController {
@@ -97,16 +99,25 @@ class DefaultBrowserToolbarController(
         // If we don't, there's a visual flickr as we navigate to Home and then display search
         // results on top it.
         if (FeatureFlags.showHomeBehindSearch && currentSession?.content?.searchTerms.isNullOrBlank()) {
+            browserAnimator.captureEngineViewAndDrawStatically {
+                navController.navigate(
+                    BrowserFragmentDirections.actionGlobalHome()
+                )
+                navController.navigate(
+                    BrowserFragmentDirections.actionGlobalSearchDialog(
+                        currentSession?.id
+                    ),
+                    getToolbarNavOptions(activity)
+                )
+            }
+        } else {
             navController.navigate(
-                BrowserFragmentDirections.actionGlobalHome()
+                BrowserFragmentDirections.actionGlobalSearchDialog(
+                    currentSession?.id
+                ),
+                getToolbarNavOptions(activity)
             )
         }
-        navController.navigate(
-            BrowserFragmentDirections.actionGlobalSearchDialog(
-                currentSession?.id
-            ),
-            getToolbarNavOptions(activity)
-        )
     }
 
     override fun handleTabCounterClick() {
@@ -163,9 +174,11 @@ class DefaultBrowserToolbarController(
     override fun handleHomeButtonClick() {
         metrics.track(Event.BrowserToolbarHomeButtonClicked)
 
-        navController.navigate(
+        browserAnimator.captureEngineViewAndDrawStatically {
-            BrowserFragmentDirections.actionGlobalHome()
+            navController.navigate(
-        )
+                BrowserFragmentDirections.actionGlobalHome()
+            )
+        }
     }
 
     companion object {

app/src/test/java/org/mozilla/fenix/components/toolbar/DefaultBrowserToolbarControllerTest.kt

@@ -356,6 +356,7 @@ class DefaultBrowserToolbarControllerTest {
         homeViewModel = homeViewModel,
         customTabSessionId = customTabSessionId,
         readerModeController = readerModeController,
+        browserAnimator = browserAnimator,
         onTabCounterClicked = {
             tabCounterClicked = true
         },