Handle page offset for grid overview

- Use TaskView's actual position with grid/fullscreen translation considered for taskPosition calculation
- Shift taskPosition by midpoint scroll, and no longer assumes midpoint is on middle of the screen
- Handle situation that TaskView is on left/right of midpoint, making the calculation generic to be able to handle grid situation

Bug: 175939487
Test: Launch modal view with wide/, RTL/non-RTL, orientation/simulated landscape combinations
Change-Id: Idd0cc9c5e24f453d830e1420319a38d3d784270d

quickstep/src/com/android/quickstep/views/TaskView.java

@@ -987,20 +987,30 @@ public class TaskView extends FrameLayout implements Reusable {
 
     private void applyTranslationX() {
         setTranslationX(mDismissTranslationX + mTaskOffsetTranslationX + mTaskResistanceTranslationX
-                + getFullscreenTrans(mFullscreenTranslationX)
-                + getNonFullscreenTrans(mNonFullscreenTranslationX)
-                + getGridTrans(mGridTranslationX));
+                + getPersistentTranslationX());
     }
 
     private void applyTranslationY() {
-        setTranslationY(
-                mDismissTranslationY + mTaskOffsetTranslationY + mTaskResistanceTranslationY
-                        + getGridTrans(mGridTranslationY) + mBoxTranslationY);
+        setTranslationY(mDismissTranslationY + mTaskOffsetTranslationY + mTaskResistanceTranslationY
+                + getPersistentTranslationY());
     }
 
-    private float getGridTrans(float endTranslation) {
-        float progress = ACCEL_DEACCEL.getInterpolation(mGridProgress);
-        return Utilities.mapRange(progress, 0, endTranslation);
+    /**
+     * Returns addition of translationX that is persistent (e.g. fullscreen and grid), and does not
+     * change according to a temporary state (e.g. task offset).
+     */
+    public float getPersistentTranslationX() {
+        return getFullscreenTrans(mFullscreenTranslationX)
+                + getNonFullscreenTrans(mNonFullscreenTranslationX)
+                + getGridTrans(mGridTranslationX);
+    }
+
+    /**
+     * Returns addition of translationY that is persistent (e.g. fullscreen and grid), and does not
+     * change according to a temporary state (e.g. task offset).
+     */
+    public float getPersistentTranslationY() {
+        return getGridTrans(mGridTranslationY) + mBoxTranslationY;
     }
 
     public FloatProperty<TaskView> getPrimaryDismissTranslationProperty() {
@@ -1275,6 +1285,11 @@ public class TaskView extends FrameLayout implements Reusable {
         return endTranslation - getFullscreenTrans(endTranslation);
     }
 
+    private float getGridTrans(float endTranslation) {
+        float progress = ACCEL_DEACCEL.getInterpolation(mGridProgress);
+        return Utilities.mapRange(progress, 0, endTranslation);
+    }
+
     public boolean isRunningTask() {
         if (getRecentsView() == null) {
             return false;