Initial commit of taskbar stashing

- Added StashedHandleViewController to provide properties such as ViewOutlineProvider to animate the handle that's shown in place of taskbar while it's stashed
- Added TaskbarStashController to coordinate the stashed state, including orchestrating the animation across taskbar controllers
- Added TaskbarStashInput consumer to detect long press in the nav region when taskbar is stashed

Behavior:
- Long pressing taskbar background animates to the stashed state by morphing the TaskbarView into the stashed handle view and offsetting the background offscreen
- We persist the stashed state across app launches and reboot; to unstash, long press the stashed handle
- We also visually unstash when going back home

Test: long press tasbkar background when in an app to stash it, long press the resulting stashed handle to unstash; while stashed, swipe up to home to also unstash until launching another app
Bug: 189503603
Change-Id: I698eff785388dff1ef717c76879719d6af236c2d

quickstep/src/com/android/launcher3/taskbar/StashedHandleViewController.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2021 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.launcher3.taskbar;
+
+import android.animation.Animator;
+import android.content.res.Resources;
+import android.graphics.Outline;
+import android.graphics.Rect;
+import android.view.View;
+import android.view.ViewOutlineProvider;
+
+import androidx.annotation.Nullable;
+
+import com.android.launcher3.R;
+import com.android.launcher3.anim.RevealOutlineAnimation;
+import com.android.launcher3.anim.RoundedRectRevealOutlineProvider;
+import com.android.quickstep.AnimatedFloat;
+
+/**
+ * Handles properties/data collection, then passes the results to our stashed handle View to render.
+ */
+public class StashedHandleViewController {
+
+    private final TaskbarActivityContext mActivity;
+    private final View mStashedHandleView;
+    private final int mStashedHandleWidth;
+    private final int mStashedHandleHeight;
+    private final AnimatedFloat mTaskbarStashedHandleAlpha = new AnimatedFloat(
+            this::updateStashedHandleAlpha);
+
+    // Initialized in init.
+    private TaskbarControllers mControllers;
+
+    // The bounds we want to clip to in the settled state when showing the stashed handle.
+    private final Rect mStashedHandleBounds = new Rect();
+    private float mStashedHandleRadius;
+
+    private boolean mIsAtStashedRevealBounds = true;
+
+    public StashedHandleViewController(TaskbarActivityContext activity, View stashedHandleView) {
+        mActivity = activity;
+        mStashedHandleView = stashedHandleView;
+        final Resources resources = mActivity.getResources();
+        mStashedHandleWidth = resources.getDimensionPixelSize(R.dimen.taskbar_stashed_handle_width);
+        mStashedHandleHeight = resources.getDimensionPixelSize(
+                R.dimen.taskbar_stashed_handle_height);
+    }
+
+    public void init(TaskbarControllers controllers) {
+        mControllers = controllers;
+        mStashedHandleView.getLayoutParams().height = mActivity.getDeviceProfile().taskbarSize;
+
+        updateStashedHandleAlpha();
+
+        final int stashedTaskbarHeight = mControllers.taskbarStashController.getStashedHeight();
+        mStashedHandleView.setOutlineProvider(new ViewOutlineProvider() {
+            @Override
+            public void getOutline(View view, Outline outline) {
+                final int stashedCenterX = view.getWidth() / 2;
+                final int stashedCenterY = view.getHeight() - stashedTaskbarHeight / 2;
+                mStashedHandleBounds.set(
+                        stashedCenterX - mStashedHandleWidth / 2,
+                        stashedCenterY - mStashedHandleHeight / 2,
+                        stashedCenterX + mStashedHandleWidth / 2,
+                        stashedCenterY + mStashedHandleHeight / 2);
+                mStashedHandleRadius = view.getHeight() / 2f;
+                outline.setRoundRect(mStashedHandleBounds, mStashedHandleRadius);
+            }
+        });
+    }
+
+    public AnimatedFloat getStashedHandleAlpha() {
+        return mTaskbarStashedHandleAlpha;
+    }
+
+    /**
+     * Creates and returns a {@link RevealOutlineAnimation} Animator that updates the stashed handle
+     * shape and size. When stashed, the shape is a thin rounded pill. When unstashed, the shape
+     * morphs into the size of where the taskbar icons will be.
+     */
+    public @Nullable Animator createRevealAnimToIsStashed(boolean isStashed) {
+        if (mIsAtStashedRevealBounds == isStashed) {
+            return null;
+        }
+        mIsAtStashedRevealBounds = isStashed;
+        final RevealOutlineAnimation handleRevealProvider = new RoundedRectRevealOutlineProvider(
+                mStashedHandleRadius, mStashedHandleRadius,
+                mControllers.taskbarViewController.getIconLayoutBounds(), mStashedHandleBounds);
+        return handleRevealProvider.createRevealAnimator(mStashedHandleView, !isStashed);
+    }
+
+    protected void updateStashedHandleAlpha() {
+        mStashedHandleView.setAlpha(mTaskbarStashedHandleAlpha.value);
+    }
+}