Reduce jank around loading view when opening data usage UI

Change-Id: I3d23d8160b046de8fe125ba0697b7b3d7786453c
Fix: 28181319
Test: robotests

src/com/android/settings/widget/LoadingViewController.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2017 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.settings.widget;
+
+import android.os.Handler;
+import android.os.Looper;
+import android.view.View;
+import android.view.animation.Animation;
+import android.view.animation.AnimationUtils;
+
+/**
+ * A helper class that manages show/hide loading spinner.
+ */
+public class LoadingViewController {
+
+    private static final long DELAY_SHOW_LOADING_CONTAINER_THRESHOLD_MS = 100L;
+
+    public final Handler mFgHandler;
+    public final View mLoadingView;
+    public final View mContentView;
+
+    public LoadingViewController(View loadingView, View contentView) {
+        mLoadingView = loadingView;
+        mContentView = contentView;
+        mFgHandler = new Handler(Looper.getMainLooper());
+    }
+
+    private Runnable mShowLoadingContainerRunnable = new Runnable() {
+        public void run() {
+            handleLoadingContainer(false /* done */, false /* animate */);
+        }
+    };
+
+    public void showContent(boolean animate) {
+        // Cancel any pending task to show the loading animation and show the list of
+        // apps directly.
+        mFgHandler.removeCallbacks(mShowLoadingContainerRunnable);
+        handleLoadingContainer(true /* show */, animate);
+    }
+
+    public void showLoadingViewDelayed() {
+        mFgHandler.postDelayed(
+                mShowLoadingContainerRunnable, DELAY_SHOW_LOADING_CONTAINER_THRESHOLD_MS);
+    }
+
+    public void handleLoadingContainer(boolean done, boolean animate) {
+        handleLoadingContainer(mLoadingView, mContentView, done, animate);
+    }
+
+    /**
+     * Show/hide loading view and content view.
+     *
+     * @param loading The loading spinner view
+     * @param content The content view
+     * @param done    If true, content is set visible and loading is set invisible.
+     * @param animate Whether or not content/loading views should animate in/out.
+     */
+    public static void handleLoadingContainer(View loading, View content, boolean done,
+            boolean animate) {
+        setViewShown(loading, !done, animate);
+        setViewShown(content, done, animate);
+    }
+
+    private static void setViewShown(final View view, boolean shown, boolean animate) {
+        if (animate) {
+            Animation animation = AnimationUtils.loadAnimation(view.getContext(),
+                    shown ? android.R.anim.fade_in : android.R.anim.fade_out);
+            if (shown) {
+                view.setVisibility(View.VISIBLE);
+            } else {
+                animation.setAnimationListener(new Animation.AnimationListener() {
+                    @Override
+                    public void onAnimationStart(Animation animation) {
+                    }
+
+                    @Override
+                    public void onAnimationRepeat(Animation animation) {
+                    }
+
+                    @Override
+                    public void onAnimationEnd(Animation animation) {
+                        view.setVisibility(View.INVISIBLE);
+                    }
+                });
+            }
+            view.startAnimation(animation);
+        } else {
+            view.clearAnimation();
+            view.setVisibility(shown ? View.VISIBLE : View.INVISIBLE);
+        }
+    }
+}