Fix bug when dragging FolderIcon between Workspace/Hotseat.

Bug: 63902464
Change-Id: I7995295d5c350720030abc6651af681c880464f8
diff --git a/src/com/android/launcher3/folder/FolderIcon.java b/src/com/android/launcher3/folder/FolderIcon.java
index c63eeb3..84ec184 100644
--- a/src/com/android/launcher3/folder/FolderIcon.java
+++ b/src/com/android/launcher3/folder/FolderIcon.java
@@ -446,6 +446,8 @@
 
         if (!mBackgroundIsVisible) return;
 
+        mPreviewItemManager.recomputePreviewDrawingParams();
+
         if (!mBackground.drawingDelegated()) {
             mBackground.drawBackground(canvas);
         }
diff --git a/src/com/android/launcher3/folder/PreviewItemManager.java b/src/com/android/launcher3/folder/PreviewItemManager.java
index bb23207..2ecb54c 100644
--- a/src/com/android/launcher3/folder/PreviewItemManager.java
+++ b/src/com/android/launcher3/folder/PreviewItemManager.java
@@ -90,8 +90,11 @@
         return animateDrawable;
     }
 
-    private void computePreviewDrawingParams(Drawable d) {
-        computePreviewDrawingParams(d.getIntrinsicWidth(), mIcon.getMeasuredWidth());
+    public void recomputePreviewDrawingParams() {
+        if (mReferenceDrawable != null) {
+            computePreviewDrawingParams(mReferenceDrawable.getIntrinsicWidth(),
+                    mIcon.getMeasuredWidth());
+        }
     }
 
     private void computePreviewDrawingParams(int drawableSize, int totalSize) {
@@ -143,8 +146,6 @@
     }
 
     public void draw(Canvas canvas) {
-        computePreviewDrawingParams(mReferenceDrawable);
-
         float firstPageItemsTransX = 0;
         if (mShouldSlideInFirstPage) {
             drawParams(canvas, mCurrentPageParams, mCurrentPageItemsTransX);