Merge "Snapshot display empty state once on creation of HistoryFragment." into ub-calculator-euler

4 files changed, 31 insertions, 46 deletions

diff --git a/src/com/android/calculator2/DragController.java b/src/com/android/calculator2/DragController.java
index 8810e7d..1716cc9 100644
--- a/src/com/android/calculator2/DragController.java
+++ b/src/com/android/calculator2/DragController.java
@@ -57,6 +57,7 @@ public final class DragController {
     private boolean mAnimationInitialized;
 
     private boolean mOneLine;
+    private boolean mIsDisplayEmpty;
 
     private AnimationController mAnimationController;
 
@@ -66,9 +67,10 @@ public final class DragController {
         mEvaluator = evaluator;
     }
 
-    public void initializeController(boolean isResult, boolean oneLine) {
+    public void initializeController(boolean isResult, boolean oneLine, boolean isDisplayEmpty) {
         mOneLine = oneLine;
-        if (EvaluatorStateUtils.isDisplayEmpty(mEvaluator)) {
+        mIsDisplayEmpty = isDisplayEmpty;
+        if (mIsDisplayEmpty) {
             // Empty display
             mAnimationController = new EmptyAnimationController();
         } else if (isResult) {
@@ -107,7 +109,8 @@ public final class DragController {
         if (yFraction > 0 && vh != null) {
             recyclerView.setVisibility(View.VISIBLE);
         }
-        if (vh != null && !EvaluatorStateUtils.isDisplayEmpty(mEvaluator)) {
+        if (vh != null && !mIsDisplayEmpty
+                && vh.getItemViewType() == HistoryAdapter.HISTORY_VIEW_TYPE) {
             final AlignedTextView formula = vh.getFormula();
             final CalculatorResult result = vh.getResult();
             final TextView date = vh.getDate();
@@ -157,7 +160,7 @@ public final class DragController {
 
             date.setTranslationY(mAnimationController.getDateTranslationY(yFraction));
             divider.setTranslationY(mAnimationController.getDateTranslationY(yFraction));
-        } else if (EvaluatorStateUtils.isDisplayEmpty(mEvaluator)) {
+        } else if (mIsDisplayEmpty) {
             // There is no current expression but we still need to collect information
             // to translate the other viewholders.
             if (!mAnimationInitialized) {
@@ -186,9 +189,9 @@ public final class DragController {
     /**
      * Reset all initialized values.
      */
-    public void initializeAnimation(boolean isResult, boolean oneLine) {
+    public void initializeAnimation(boolean isResult, boolean oneLine, boolean isDisplayEmpty) {
         mAnimationInitialized = false;
-        initializeController(isResult, oneLine);
+        initializeController(isResult, oneLine, isDisplayEmpty);
     }
 
     public interface AnimateTextInterface {
diff --git a/src/com/android/calculator2/EvaluatorStateUtils.java b/src/com/android/calculator2/EvaluatorStateUtils.java
deleted file mode 100644
index 2d8eddc..0000000
--- a/src/com/android/calculator2/EvaluatorStateUtils.java
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
- * Copyright (C) 2016 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.calculator2;
-
-/**
- * Utils class to get the state of the passed-in Evaluator.
- */
-
-public class EvaluatorStateUtils {
-    public static boolean isDisplayEmpty(Evaluator evaluator) {
-        if (evaluator != null) {
-            final CalculatorExpr mainExpr = evaluator.getExpr(Evaluator.MAIN_INDEX);
-            return mainExpr == null || mainExpr.isEmpty();
-        } else {
-            return true;
-        }
-    }
-}
diff --git a/src/com/android/calculator2/HistoryAdapter.java b/src/com/android/calculator2/HistoryAdapter.java
index fe2f2c0..629abe9 100644
--- a/src/com/android/calculator2/HistoryAdapter.java
+++ b/src/com/android/calculator2/HistoryAdapter.java
@@ -34,7 +34,7 @@ public class HistoryAdapter extends RecyclerView.Adapter<HistoryAdapter.ViewHold
     private static final String TAG = "HistoryAdapter";
 
     private static final int EMPTY_VIEW_TYPE = 0;
-    private static final int HISTORY_VIEW_TYPE = 1;
+    public static final int HISTORY_VIEW_TYPE = 1;
 
     private Evaluator mEvaluator;
 
@@ -44,6 +44,7 @@ public class HistoryAdapter extends RecyclerView.Adapter<HistoryAdapter.ViewHold
 
     private boolean mIsResultLayout;
     private boolean mIsOneLine;
+    private boolean mIsDisplayEmpty;
 
     public HistoryAdapter(ArrayList<HistoryItem> dataSet) {
         mDataSet = dataSet;
@@ -135,12 +136,16 @@ public class HistoryAdapter extends RecyclerView.Adapter<HistoryAdapter.ViewHold
         mIsOneLine = isOneLine;
     }
 
+    public void setIsDisplayEmpty(boolean isDisplayEmpty) {
+        mIsDisplayEmpty = isDisplayEmpty;
+    }
+
     public void setEvaluator(Evaluator evaluator) {
         mEvaluator = evaluator;
     }
 
     private int getEvaluatorIndex(int position) {
-        if (EvaluatorStateUtils.isDisplayEmpty(mEvaluator) || mIsResultLayout) {
+        if (mIsDisplayEmpty || mIsResultLayout) {
             return (int) (mEvaluator.getMaxIndex() - position);
         } else {
             // Account for the additional "Current Expression" with the +1.
diff --git a/src/com/android/calculator2/HistoryFragment.java b/src/com/android/calculator2/HistoryFragment.java
index 7da375d..6847cc9 100644
--- a/src/com/android/calculator2/HistoryFragment.java
+++ b/src/com/android/calculator2/HistoryFragment.java
@@ -47,6 +47,8 @@ public class HistoryFragment extends Fragment implements DragLayout.DragCallback
 
     private ArrayList<HistoryItem> mDataSet = new ArrayList<>();
 
+    private boolean mIsDisplayEmpty;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -113,13 +115,19 @@ public class HistoryFragment extends Fragment implements DragLayout.DragCallback
         final boolean isResultLayout = activity.isResultLayout();
         final boolean isOneLine = activity.isOneLine();
 
-        initializeController(isResultLayout, isOneLine);
+        // Snapshot display state here. For the rest of the lifecycle of this current
+        // HistoryFragment, this is what we will consider the display state.
+        // In rare cases, the display state can change after our adapter is initialized.
+        final CalculatorExpr mainExpr = mEvaluator.getExpr(Evaluator.MAIN_INDEX);
+        mIsDisplayEmpty = mainExpr == null || mainExpr.isEmpty();
+
+        initializeController(isResultLayout, isOneLine, mIsDisplayEmpty);
 
         final long maxIndex = mEvaluator.getMaxIndex();
 
         final ArrayList<HistoryItem> newDataSet = new ArrayList<>();
 
-        if (!EvaluatorStateUtils.isDisplayEmpty(mEvaluator) && !isResultLayout) {
+        if (!mIsDisplayEmpty && !isResultLayout) {
             // Add the current expression as the first element in the list (the layout is
             // reversed and we want the current expression to be the last one in the
             // RecyclerView).
@@ -142,7 +150,7 @@ public class HistoryFragment extends Fragment implements DragLayout.DragCallback
         mAdapter.setDataSet(mDataSet);
         mAdapter.setIsResultLayout(isResultLayout);
         mAdapter.setIsOneLine(activity.isOneLine());
-
+        mAdapter.setIsDisplayEmpty(mIsDisplayEmpty);
         mAdapter.notifyDataSetChanged();
     }
 
@@ -151,7 +159,8 @@ public class HistoryFragment extends Fragment implements DragLayout.DragCallback
         super.onStart();
 
         final Calculator activity = (Calculator) getActivity();
-        mDragController.initializeAnimation(activity.isResultLayout(), activity.isOneLine());
+        mDragController.initializeAnimation(activity.isResultLayout(), activity.isOneLine(), 
+                mIsDisplayEmpty);
     }
 
     @Override
@@ -181,14 +190,14 @@ public class HistoryFragment extends Fragment implements DragLayout.DragCallback
         }
     }
 
-    private void initializeController(boolean isResult, boolean isOneLine) {
+    private void initializeController(boolean isResult, boolean isOneLine, boolean isDisplayEmpty) {
         mDragController.setDisplayFormula(
                 (CalculatorFormula) getActivity().findViewById(R.id.formula));
         mDragController.setDisplayResult(
                 (CalculatorResult) getActivity().findViewById(R.id.result));
         mDragController.setToolbar(getActivity().findViewById(R.id.toolbar));
         mDragController.setEvaluator(mEvaluator);
-        mDragController.initializeController(isResult, isOneLine);
+        mDragController.initializeController(isResult, isOneLine, isDisplayEmpty);
     }
 
     public boolean stopActionModeOrContextMenu() {