Merge "Fix folder preview animation when adding or removing icons." into tm-qpr-dev am: 34958f4bdf

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/18568370

Change-Id: I189846b43af30c3c5166f4495e3184695daa96e2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

src/com/android/launcher3/folder/PreviewItemManager.java

@@ -79,6 +79,8 @@ public class PreviewItemManager {
     private int mPrevTopPadding = -1;
     private Drawable mReferenceDrawable = null;
 
+    private int mNumOfPrevItems = 0;
+
     // These hold the first page preview items
     private ArrayList<PreviewItemDrawingParams> mFirstPageParams = new ArrayList<>();
     // These hold the current page preview items. It is empty if the current page is the first page.
@@ -254,7 +256,6 @@ public class PreviewItemManager {
 
     void buildParamsForPage(int page, ArrayList<PreviewItemDrawingParams> params, boolean animate) {
         List<WorkspaceItemInfo> items = mIcon.getPreviewItemsOnPage(page);
-        int prevNumItems = params.size();
 
         // We adjust the size of the list to match the number of items in the preview.
         while (items.size() < params.size()) {
@@ -278,8 +279,9 @@ public class PreviewItemManager {
                     mReferenceDrawable = p.drawable;
                 }
             } else {
-                FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, i, prevNumItems, i,
-                        numItemsInFirstPagePreview, DROP_IN_ANIMATION_DURATION, null);
+                FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, i,
+                        mNumOfPrevItems, i, numItemsInFirstPagePreview, DROP_IN_ANIMATION_DURATION,
+                        null);
 
                 if (p.anim != null) {
                     if (p.anim.hasEqualFinalState(anim)) {
@@ -318,7 +320,9 @@ public class PreviewItemManager {
     }
 
     void updatePreviewItems(boolean animate) {
+        int numOfPrevItemsAux = mFirstPageParams.size();
         buildParamsForPage(0, mFirstPageParams, animate);
+        mNumOfPrevItems = numOfPrevItemsAux;
     }
 
     void updatePreviewItems(Predicate<WorkspaceItemInfo> itemCheck) {