Launch split tasks at beginning of animation instead of the end

* Ideally we animate the live leashes from the placeholder tasks,
that's a lot more changes at this moment so we don't do that
* Instead we just hold off fading in the leashes until the very
end of the animation
* This way taskbar can scale down correctly in both contextual and
app pair launch cases since now launcher visibility will be changed
at the same time

Bug: 308851855
Test: Launches are a bit snappier from workspace/all apps compared
to overview, but in a good way!(?)

Change-Id: I73a9284a2b1a993c5a020396e2aca8499fc5eb09
diff --git a/quickstep/src/com/android/launcher3/taskbar/LauncherTaskbarUIController.java b/quickstep/src/com/android/launcher3/taskbar/LauncherTaskbarUIController.java
index 8c8dd1f..ed89889 100644
--- a/quickstep/src/com/android/launcher3/taskbar/LauncherTaskbarUIController.java
+++ b/quickstep/src/com/android/launcher3/taskbar/LauncherTaskbarUIController.java
@@ -225,11 +225,7 @@
         }
 
         mTaskbarLauncherStateController.updateStateForFlag(FLAG_VISIBLE, isVisible);
-        // TODO(b/308851855): Skip animation for launching split from home, will refine later
-        boolean skipAnimForSplit = enableSplitContextually() &&
-                mLauncher.areBothSplitAppsConfirmed() &&
-                mLauncher.getStateManager().getState() == LauncherState.NORMAL;
-        if (skipAnimForSplit || fromInit) {
+        if (fromInit) {
             duration = 0;
         }
         return mTaskbarLauncherStateController.applyState(duration, startAnimation);
diff --git a/quickstep/src/com/android/quickstep/util/SplitAnimationController.kt b/quickstep/src/com/android/quickstep/util/SplitAnimationController.kt
index a2d3859..bfebfdc 100644
--- a/quickstep/src/com/android/quickstep/util/SplitAnimationController.kt
+++ b/quickstep/src/com/android/quickstep/util/SplitAnimationController.kt
@@ -880,11 +880,30 @@
             }
         }
 
+        if (splitRoot1 != null) {
+            // Set the highest level split root alpha; we could technically use the parent of
+            // either splitRoot1 or splitRoot2
+            val parentToken = splitRoot1.parent
+            var rootLayer: Change? = null
+            if (parentToken != null) {
+                rootLayer = transitionInfo.getChange(parentToken)
+            }
+            if (rootLayer != null && rootLayer.leash != null) {
+                openingTargets.add(rootLayer.leash)
+            }
+        }
+
         val animTransaction = Transaction()
         val animator = ValueAnimator.ofFloat(0f, 1f)
         animator.setDuration(QuickstepTransitionManager.SPLIT_LAUNCH_DURATION.toLong())
         animator.addUpdateListener { valueAnimator: ValueAnimator ->
-            val progress = valueAnimator.animatedFraction
+            val progress =
+                    Interpolators.clampToProgress(
+                            Interpolators.LINEAR,
+                            valueAnimator.animatedFraction,
+                            0.8f,
+                            1f
+                    )
             for (leash in openingTargets) {
                 animTransaction.setAlpha(leash, progress)
             }
@@ -906,19 +925,6 @@
             }
         )
 
-        if (splitRoot1 != null) {
-            // Set the highest level split root alpha; we could technically use the parent of
-            // either splitRoot1 or splitRoot2
-            val parentToken = splitRoot1.parent
-            var rootLayer: Change? = null
-            if (parentToken != null) {
-                rootLayer = transitionInfo.getChange(parentToken)
-            }
-            if (rootLayer != null && rootLayer.leash != null) {
-                t.setAlpha(rootLayer.leash, 1f)
-            }
-        }
-
         t.apply()
         animator.start()
     }
diff --git a/quickstep/src/com/android/quickstep/util/SplitToWorkspaceController.java b/quickstep/src/com/android/quickstep/util/SplitToWorkspaceController.java
index 16d707b..9dc8ad6 100644
--- a/quickstep/src/com/android/quickstep/util/SplitToWorkspaceController.java
+++ b/quickstep/src/com/android/quickstep/util/SplitToWorkspaceController.java
@@ -172,6 +172,11 @@
             private boolean mIsCancelled = false;
 
             @Override
+            public void onAnimationStart(Animator animation) {
+                mController.launchSplitTasks(aBoolean -> cleanUp());
+            }
+
+            @Override
             public void onAnimationCancel(Animator animation) {
                 mIsCancelled = true;
                 cleanUp();
@@ -180,7 +185,6 @@
             @Override
             public void onAnimationEnd(Animator animation) {
                 if (!mIsCancelled) {
-                    mController.launchSplitTasks(aBoolean -> cleanUp());
                     InteractionJankMonitorWrapper.end(Cuj.CUJ_SPLIT_SCREEN_ENTER);
                 }
             }