Using support lib implementation for launcher preference

Bug: 117519297
Change-Id: Icea5e022a337436e48db9376fd441f805dc34e54

src/com/android/launcher3/settings/PreferenceHighlighter.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2018 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.settings;
+
+import static androidx.core.graphics.ColorUtils.setAlphaComponent;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
+import android.animation.ValueAnimator;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.util.Property;
+import android.view.View;
+
+import com.android.launcher3.util.Themes;
+
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.RecyclerView.ItemDecoration;
+import androidx.recyclerview.widget.RecyclerView.State;
+import androidx.recyclerview.widget.RecyclerView.ViewHolder;
+
+/**
+ * Utility class for highlighting a preference
+ */
+public class PreferenceHighlighter extends ItemDecoration implements Runnable {
+
+    private static final Property<PreferenceHighlighter, Integer> HIGHLIGHT_COLOR =
+            new Property<PreferenceHighlighter, Integer>(Integer.TYPE, "highlightColor") {
+
+                @Override
+                public Integer get(PreferenceHighlighter highlighter) {
+                    return highlighter.mHighlightColor;
+                }
+
+                @Override
+                public void set(PreferenceHighlighter highlighter, Integer value) {
+                    highlighter.mHighlightColor = value;
+                    highlighter.mRv.invalidateItemDecorations();
+                }
+            };
+
+    private static final long HIGHLIGHT_DURATION = 15000L;
+    private static final long HIGHLIGHT_FADE_OUT_DURATION = 500L;
+    private static final long HIGHLIGHT_FADE_IN_DURATION = 200L;
+    private static final int END_COLOR = setAlphaComponent(Color.WHITE, 0);
+
+    private final Paint mPaint = new Paint();
+    private final RecyclerView mRv;
+    private final int mIndex;
+
+    private boolean mHighLightStarted = false;
+    private int mHighlightColor = END_COLOR;
+
+
+    public PreferenceHighlighter(RecyclerView rv, int index) {
+        mRv = rv;
+        mIndex = index;
+    }
+
+    @Override
+    public void run() {
+        mRv.addItemDecoration(this);
+        mRv.smoothScrollToPosition(mIndex);
+    }
+
+    @Override
+    public void onDraw(Canvas c, RecyclerView parent, State state) {
+        ViewHolder holder = parent.findViewHolderForAdapterPosition(mIndex);
+        if (holder == null) {
+            return;
+        }
+        if (!mHighLightStarted && state.getRemainingScrollVertical() != 0) {
+            // Wait until scrolling stopped
+            return;
+        }
+
+        if (!mHighLightStarted) {
+            // Start highlight
+            int colorTo = setAlphaComponent(Themes.getColorAccent(mRv.getContext()), 66);
+            ObjectAnimator anim = ObjectAnimator.ofArgb(this, HIGHLIGHT_COLOR, END_COLOR, colorTo);
+            anim.setDuration(HIGHLIGHT_FADE_IN_DURATION);
+            anim.setRepeatMode(ValueAnimator.REVERSE);
+            anim.setRepeatCount(4);
+            anim.addListener(new AnimatorListenerAdapter() {
+                @Override
+                public void onAnimationEnd(Animator animation) {
+                    removeHighlight();
+                }
+            });
+            anim.start();
+            mHighLightStarted = true;
+        }
+
+        View view = holder.itemView;
+        mPaint.setColor(mHighlightColor);
+        c.drawRect(0, view.getY(), parent.getWidth(), view.getY() + view.getHeight(), mPaint);
+    }
+
+    private void removeHighlight() {
+        ObjectAnimator anim = ObjectAnimator.ofArgb(
+                this, HIGHLIGHT_COLOR, mHighlightColor, END_COLOR);
+        anim.setDuration(HIGHLIGHT_FADE_OUT_DURATION);
+        anim.setStartDelay(HIGHLIGHT_DURATION);
+        anim.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mRv.removeItemDecoration(PreferenceHighlighter.this);
+            }
+        });
+        anim.start();
+    }
+}