Animate SplitPlaceholderView when entering split from overview

Bugs tracked in b/181704764

Bug: 181704764
Test: Tested on phone and large screen in multiple orientations

Change-Id: I07509006ae3d1f4425dc5119d0c8ed52b41a3bc2

src/com/android/launcher3/Utilities.java

@@ -380,6 +380,21 @@ public final class Utilities {
         return scale;
     }
 
+    /**
+     * Similar to {@link #scaleRectAboutCenter(Rect, float)} except this allows different scales
+     * for X and Y
+     */
+    public static void scaleRectFAboutCenter(RectF r, float scaleX, float scaleY) {
+        float px = r.centerX();
+        float py = r.centerY();
+        r.offset(-px, -py);
+        r.left = r.left * scaleX;
+        r.top = r.top * scaleY;
+        r.right = r.right * scaleX;
+        r.bottom = r.bottom * scaleY;
+        r.offset(px, py);
+    }
+
     /**
      * Maps t from one range to another range.
      * @param t The value to map.