Adds BackGestureIndicatorView to animate left and right insets

Bug: 146004827
Test: make RunSettingsRoboTests ROBOTEST_FILTER=BackGestureIndicatorViewTest

Change-Id: Id8c01bf047138a1721237f368f269c6def964515
diff --git a/res/layout/back_gesture_indicator_container.xml b/res/layout/back_gesture_indicator_container.xml
new file mode 100644
index 0000000..17b9126
--- /dev/null
+++ b/res/layout/back_gesture_indicator_container.xml
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 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
+  -->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="horizontal"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <ImageView
+        android:layout_width="@dimen/back_gesture_indicator_width"
+        android:layout_height="match_parent"
+        android:id="@+id/indicator_left">
+    </ImageView>
+
+    <Space
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:layout_weight="1" />
+
+    <ImageView
+        android:layout_width="@dimen/back_gesture_indicator_width"
+        android:layout_height="match_parent"
+        android:id="@+id/indicator_right">
+    </ImageView>
+
+</LinearLayout>
+
diff --git a/res/values/colors.xml b/res/values/colors.xml
index a1cb8fc..3fd77e8 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -146,4 +146,6 @@
     <color name="dialog_background">@*android:color/background_device_default_light</color>
 
     <color name="face_intro_outline">#ffdadce0</color>
+
+    <color name="back_gesture_indicator">#4182ef</color>
 </resources>
\ No newline at end of file
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 41c059c..2e71893 100755
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -403,6 +403,8 @@
     <!-- System navigation settings illustration height -->
     <dimen name="system_navigation_illustration_height">320dp</dimen>
 
+    <dimen name="back_gesture_indicator_width">60dp</dimen>
+
     <!-- Header title size of advanced bluetooth device -->
     <dimen name="advanced_bluetooth_header_title_text_size">16sp</dimen>
 
diff --git a/src/com/android/settings/gestures/BackGestureIndicatorDrawable.java b/src/com/android/settings/gestures/BackGestureIndicatorDrawable.java
new file mode 100644
index 0000000..2d09e6b
--- /dev/null
+++ b/src/com/android/settings/gestures/BackGestureIndicatorDrawable.java
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2019 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.gestures;
+
+import android.animation.TimeAnimator;
+import android.annotation.IntRange;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.ColorFilter;
+import android.graphics.Paint;
+import android.graphics.Rect;
+import android.graphics.drawable.Drawable;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.settings.R;
+
+/** A drawable to animate the inset back gesture in both edges of the screen */
+public class BackGestureIndicatorDrawable extends Drawable {
+
+    private static final String TAG = "BackGestureIndicatorDrawable";
+
+    private static final int MSG_SET_INDICATOR_WIDTH = 1;
+    private static final int MSG_HIDE_INDICATOR = 3;
+
+    private static final long ANIMATION_DURATION_MS = 200L;
+    private static final long HIDE_DELAY_MS = 700L;
+
+    private static final int ALPHA_MAX = 64;
+
+    private Context mContext;
+
+    private Paint mPaint = new Paint();
+    private boolean mReversed;
+
+    private float mFinalWidth;
+    private float mCurrentWidth;
+    private float mWidthChangePerMs;
+
+    private TimeAnimator mTimeAnimator = new TimeAnimator();
+
+    private final Handler mHandler = new Handler(Looper.getMainLooper()) {
+        @Override
+        public void handleMessage(Message msg) {
+            switch(msg.what) {
+                case MSG_SET_INDICATOR_WIDTH:
+                    mTimeAnimator.end();
+                    mFinalWidth = msg.arg1;
+                    mWidthChangePerMs = Math.abs(mCurrentWidth - mFinalWidth)
+                            / ANIMATION_DURATION_MS;
+                    mTimeAnimator.start();
+                    break;
+                case MSG_HIDE_INDICATOR:
+                    mCurrentWidth = mFinalWidth;
+                    removeMessages(MSG_SET_INDICATOR_WIDTH);
+                    sendMessageDelayed(obtainMessage(MSG_SET_INDICATOR_WIDTH, 0, 0), HIDE_DELAY_MS);
+                    invalidateSelf();
+                    break;
+                default:
+                    break;
+            }
+        }
+    };
+
+    /**
+     * Creates an indicator drawable that responds to back gesture inset size change
+     * @param reversed If false, indicator will expand right. If true, indicator will expand left
+     */
+    public BackGestureIndicatorDrawable(Context context, boolean reversed) {
+        mContext = context;
+        mReversed = reversed;
+
+        // Restart the timer whenever a change is detected, so we can shrink/fade the indicators
+        mTimeAnimator.setTimeListener((TimeAnimator animation, long totalTime, long deltaTime) -> {
+            updateCurrentWidth(totalTime, deltaTime);
+            invalidateSelf();
+        });
+    }
+
+    private void updateCurrentWidth(long totalTime, long deltaTime) {
+        synchronized (mTimeAnimator) {
+            float step = deltaTime * mWidthChangePerMs;
+            if (totalTime >= ANIMATION_DURATION_MS
+                    || step >= Math.abs(mFinalWidth - mCurrentWidth)) {
+                mCurrentWidth = mFinalWidth;
+                mTimeAnimator.end();
+            } else {
+                float direction = mCurrentWidth < mFinalWidth ? 1 : -1;
+                mCurrentWidth += direction * step;
+            }
+        }
+    }
+
+    @Override
+    public void draw(@NonNull Canvas canvas) {
+
+        mPaint.setAntiAlias(true);
+        mPaint.setColor(mContext.getResources().getColor(R.color.back_gesture_indicator));
+        mPaint.setAlpha(ALPHA_MAX);
+
+        final int top = 0;
+        final int bottom = canvas.getHeight();
+        final int width = (int) mCurrentWidth;
+
+        Rect rect = new Rect(0, top, width, bottom);
+        if (mReversed) {
+            rect.offset(canvas.getWidth() - width, 0);
+        }
+
+        canvas.drawRect(rect, mPaint);
+    }
+
+    @Override
+    public void setAlpha(@IntRange(from = 0, to = 255) int alpha) {
+
+    }
+
+    @Override
+    public void setColorFilter(@Nullable ColorFilter colorFilter) {
+
+    }
+
+    @Override
+    public int getOpacity() {
+        return 0;
+    }
+
+    /**
+     * Sets the visible width of the indicator in pixels.
+     */
+    public void setWidth(int width) {
+        if (width == 0) {
+            mHandler.sendEmptyMessage(MSG_HIDE_INDICATOR);
+        } else {
+            mHandler.sendMessage(mHandler.obtainMessage(MSG_SET_INDICATOR_WIDTH, width, 0));
+        }
+    }
+
+    @VisibleForTesting
+    public int getWidth() {
+        return (int) mFinalWidth;
+    }
+}
diff --git a/src/com/android/settings/gestures/BackGestureIndicatorView.java b/src/com/android/settings/gestures/BackGestureIndicatorView.java
new file mode 100644
index 0000000..2bb8435
--- /dev/null
+++ b/src/com/android/settings/gestures/BackGestureIndicatorView.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2019 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.gestures;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.PixelFormat;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.WindowManager;
+import android.widget.ImageView;
+import android.widget.LinearLayout;
+
+import com.android.settings.R;
+
+/**
+ * A linear layout containing the left and right location indicators.
+ */
+public class BackGestureIndicatorView extends LinearLayout {
+    private ViewGroup mLayout;
+    private ImageView mLeftIndicator;
+    private ImageView mRightIndicator;
+    private BackGestureIndicatorDrawable mLeftDrawable;
+    private BackGestureIndicatorDrawable mRightDrawable;
+
+    public BackGestureIndicatorView(Context context) {
+        super(context);
+
+        LayoutInflater factory = LayoutInflater.from(context);
+        mLayout = (ViewGroup) factory.inflate(R.layout.back_gesture_indicator_container,
+                this, false);
+
+        if (mLayout == null) {
+            return;
+        }
+
+        addView(mLayout);
+
+        mLeftDrawable = new BackGestureIndicatorDrawable(context, false);
+        mRightDrawable = new BackGestureIndicatorDrawable(context, true);
+
+        mLeftIndicator = mLayout.findViewById(R.id.indicator_left);
+        mRightIndicator = mLayout.findViewById(R.id.indicator_right);
+
+        mLeftIndicator.setImageDrawable(mLeftDrawable);
+        mRightIndicator.setImageDrawable(mRightDrawable);
+
+        TypedArray a = context.obtainStyledAttributes(new int[] {
+                android.R.attr.windowLightNavigationBar,
+                android.R.attr.windowLightStatusBar});
+        if (a.getBoolean(0, false)) {
+            setSystemUiVisibility(
+                    getSystemUiVisibility() | View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR);
+        }
+        if (a.getBoolean(1, false)) {
+            setSystemUiVisibility(
+                    getSystemUiVisibility() | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
+        }
+        a.recycle();
+    }
+
+    public void setIndicatorWidth(int width, boolean leftIndicator) {
+        BackGestureIndicatorDrawable indicator = leftIndicator ? mLeftDrawable : mRightDrawable;
+        indicator.setWidth(width);
+    }
+
+    public WindowManager.LayoutParams getLayoutParams(
+            WindowManager.LayoutParams parentWindowAttributes) {
+        int copiedFlags = (parentWindowAttributes.flags
+                & WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
+        final WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
+                ViewGroup.LayoutParams.MATCH_PARENT,
+                ViewGroup.LayoutParams.MATCH_PARENT,
+                WindowManager.LayoutParams.TYPE_APPLICATION,
+                WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED
+                        | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
+                        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
+                        | copiedFlags,
+                PixelFormat.TRANSLUCENT);
+
+        lp.setTitle("BackGestureIndicatorView");
+        lp.token = getContext().getActivityToken();
+        return lp;
+    }
+}
diff --git a/tests/robotests/src/com/android/settings/gestures/BackGestureIndicatorViewTest.java b/tests/robotests/src/com/android/settings/gestures/BackGestureIndicatorViewTest.java
new file mode 100644
index 0000000..8d43aaa
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/gestures/BackGestureIndicatorViewTest.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2019 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.gestures;
+
+import static org.junit.Assert.assertEquals;
+
+import android.content.Context;
+import android.widget.ImageView;
+
+import com.android.settings.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class BackGestureIndicatorViewTest {
+
+    private Context mContext;
+
+    private BackGestureIndicatorDrawable mLeftDrawable;
+    private BackGestureIndicatorDrawable mRightDrawable;
+
+    private BackGestureIndicatorView mView;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        mContext = RuntimeEnvironment.application;
+        mView = new BackGestureIndicatorView(mContext);
+
+        mLeftDrawable = (BackGestureIndicatorDrawable) ((ImageView) mView.findViewById(
+                R.id.indicator_left)).getDrawable();
+        mRightDrawable = (BackGestureIndicatorDrawable) ((ImageView) mView.findViewById(
+                R.id.indicator_right)).getDrawable();
+    }
+
+    @Test
+    public void testSetIndicatoreWidth() {
+        mView.setIndicatorWidth(25, true);
+        mView.setIndicatorWidth(52, false);
+
+        assertEquals(25, mLeftDrawable.getWidth());
+        assertEquals(52, mRightDrawable.getWidth());
+    }
+}