src/com/android/launcher3/views/RecyclerViewFastScroller.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * 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.launcher3.views;

 import static android.view.HapticFeedbackConstants.CLOCK_TICK;

 import static androidx.recyclerview.widget.RecyclerView.SCROLL_STATE_IDLE;

 import android.animation.ObjectAnimator;
 import android.content.Context;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Insets;
 import android.graphics.Paint;
 import android.graphics.Point;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import android.os.Build;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.util.Property;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.view.WindowInsets;
 import android.widget.TextView;

 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.recyclerview.widget.RecyclerView;

 import com.android.launcher3.BaseRecyclerView;
 import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
 import com.android.launcher3.graphics.FastScrollThumbDrawable;
 import com.android.launcher3.util.Themes;

 import java.util.Collections;
 import java.util.List;

 /**
  * The track and scrollbar that shows when you scroll the list.
  */
 public class RecyclerViewFastScroller extends View {
     private static final String TAG = "RecyclerViewFastScroller";
     private static final boolean DEBUG = false;
     private static final int FASTSCROLL_THRESHOLD_MILLIS = 40;
     private static final int SCROLL_DELTA_THRESHOLD_DP = 4;

     // Track is very narrow to target and correctly. This is especially the case if a user is
     // using a hardware case. Even if x is offset by following amount, we consider it to be valid.
     private static final int SCROLLBAR_LEFT_OFFSET_TOUCH_DELEGATE_DP = 5;
     private static final Rect sTempRect = new Rect();

     private static final Property<RecyclerViewFastScroller, Integer> TRACK_WIDTH =
             new Property<RecyclerViewFastScroller, Integer>(Integer.class, "width") {

                 @Override
                 public Integer get(RecyclerViewFastScroller scrollBar) {
                     return scrollBar.mWidth;
                 }

                 @Override
                 public void set(RecyclerViewFastScroller scrollBar, Integer value) {
                     scrollBar.setTrackWidth(value);
                 }
             };

     private final static int MAX_TRACK_ALPHA = 30;
     private final static int SCROLL_BAR_VIS_DURATION = 150;

     private static final List<Rect> SYSTEM_GESTURE_EXCLUSION_RECT =
             Collections.singletonList(new Rect());

     private final int mMinWidth;
     private final int mMaxWidth;
     private final int mThumbPadding;

     /** Keeps the last known scrolling delta/velocity along y-axis. */
     private int mDy = 0;
     private final float mDeltaThreshold;
     private final float mScrollbarLeftOffsetTouchDelegate;

     private final ViewConfiguration mConfig;

     // Current width of the track
     private int mWidth;
     private ObjectAnimator mWidthAnimator;

     private final Paint mThumbPaint;
     protected final int mThumbHeight;
     private final RectF mThumbBounds = new RectF();
     private final Point mThumbDrawOffset = new Point();

     private final Paint mTrackPaint;

     private float mLastTouchY;
     private boolean mIsDragging;
     private boolean mIsThumbDetached;
     private final boolean mCanThumbDetach;
     private boolean mIgnoreDragGesture;
     private boolean mIsRecyclerViewFirstChildInParent = true;
     private long mDownTimeStampMillis;

     // This is the offset from the top of the scrollbar when the user first starts touching.  To
     // prevent jumping, this offset is applied as the user scrolls.
     protected int mTouchOffsetY;
     protected int mThumbOffsetY;
     protected int mRvOffsetY;

     // Fast scroller popup
     private TextView mPopupView;
     private boolean mPopupVisible;
     private String mPopupSectionName;
     private Insets mSystemGestureInsets;

     protected BaseRecyclerView mRv;
     private RecyclerView.OnScrollListener mOnScrollListener;
     @Nullable private OnFastScrollChangeListener mOnFastScrollChangeListener;

     private int mDownX;
     private int mDownY;
     private int mLastY;

     public RecyclerViewFastScroller(Context context) {
         this(context, null);
     }

     public RecyclerViewFastScroller(Context context, AttributeSet attrs) {
         this(context, attrs, 0);
     }

     public RecyclerViewFastScroller(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);

         mTrackPaint = new Paint();
         mTrackPaint.setColor(Themes.getAttrColor(context, android.R.attr.textColorPrimary));
         mTrackPaint.setAlpha(MAX_TRACK_ALPHA);

         mThumbPaint = new Paint();
         mThumbPaint.setAntiAlias(true);
         mThumbPaint.setColor(Themes.getColorAccent(context));
         mThumbPaint.setStyle(Paint.Style.FILL);

         Resources res = getResources();
         mWidth = mMinWidth = res.getDimensionPixelSize(R.dimen.fastscroll_track_min_width);
         mMaxWidth = res.getDimensionPixelSize(R.dimen.fastscroll_track_max_width);

         mThumbPadding = res.getDimensionPixelSize(R.dimen.fastscroll_thumb_padding);
         mThumbHeight = res.getDimensionPixelSize(R.dimen.fastscroll_thumb_height);

         mConfig = ViewConfiguration.get(context);
         mDeltaThreshold = res.getDisplayMetrics().density * SCROLL_DELTA_THRESHOLD_DP;
         mScrollbarLeftOffsetTouchDelegate = res.getDisplayMetrics().density
                 * SCROLLBAR_LEFT_OFFSET_TOUCH_DELEGATE_DP;

         TypedArray ta =
                 context.obtainStyledAttributes(attrs, R.styleable.RecyclerViewFastScroller, defStyleAttr, 0);
         mCanThumbDetach = ta.getBoolean(R.styleable.RecyclerViewFastScroller_canThumbDetach, false);
         ta.recycle();
     }

     public void setRecyclerView(BaseRecyclerView rv, TextView popupView) {
         if (mRv != null && mOnScrollListener != null) {
             mRv.removeOnScrollListener(mOnScrollListener);
         }
         mRv = rv;

         mRv.addOnScrollListener(mOnScrollListener = new RecyclerView.OnScrollListener() {
             @Override
             public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                 mDy = dy;

                 // TODO(winsonc): If we want to animate the section heads while scrolling, we can
                 //                initiate that here if the recycler view scroll state is not
                 //                RecyclerView.SCROLL_STATE_IDLE.

                 mRv.onUpdateScrollbar(dy);
             }
         });

         mPopupView = popupView;
         mPopupView.setBackground(
                 new FastScrollThumbDrawable(mThumbPaint, Utilities.isRtl(getResources())));
     }

     public void reattachThumbToScroll() {
         mIsThumbDetached = false;
     }

     public void setThumbOffsetY(int y) {
         if (mThumbOffsetY == y) {
             int rvCurrentOffsetY = mRv.getCurrentScrollY();
             if (mRvOffsetY != rvCurrentOffsetY) {
                 mRvOffsetY = mRv.getCurrentScrollY();
                 notifyScrollChanged();
             }
             return;
         }
         updatePopupY(y);
         mThumbOffsetY = y;
         invalidate();
         mRvOffsetY = mRv.getCurrentScrollY();
         notifyScrollChanged();
     }

     public int getThumbOffsetY() {
         return mThumbOffsetY;
     }

     private void setTrackWidth(int width) {
         if (mWidth == width) {
             return;
         }
         mWidth = width;
         invalidate();
     }

     public int getThumbHeight() {
         return mThumbHeight;
     }

     public boolean isDraggingThumb() {
         return mIsDragging;
     }

     public boolean isThumbDetached() {
         return mIsThumbDetached;
     }

     /**
      * Handles the touch event and determines whether to show the fast scroller (or updates it if
      * it is already showing).
      */
     public boolean handleTouchEvent(MotionEvent ev, Point offset) {
         int x = (int) ev.getX() - offset.x;
         int y = (int) ev.getY() - offset.y;

         switch (ev.getAction()) {
             case MotionEvent.ACTION_DOWN:
                 // Keep track of the down positions
                 mDownX = x;
                 mDownY = mLastY = y;
                 mDownTimeStampMillis = ev.getDownTime();

                 if ((Math.abs(mDy) < mDeltaThreshold &&
                         mRv.getScrollState() != SCROLL_STATE_IDLE)) {
                     // now the touch events are being passed to the {@link WidgetCell} until the
                     // touch sequence goes over the touch slop.
                     mRv.stopScroll();
                 }
                 if (isNearThumb(x, y)) {
                     mTouchOffsetY = mDownY - mThumbOffsetY;
                 }
                 break;
             case MotionEvent.ACTION_MOVE:
                 mLastY = y;
                 int absDeltaY = Math.abs(y - mDownY);
                 int absDeltaX = Math.abs(x - mDownX);

                 // Check if we should start scrolling, but ignore this fastscroll gesture if we have
                 // exceeded some fixed movement
                 mIgnoreDragGesture |= absDeltaY > mConfig.getScaledPagingTouchSlop();

                 if (!mIsDragging && !mIgnoreDragGesture && mRv.supportsFastScrolling()) {
                     if ((isNearThumb(mDownX, mLastY) && ev.getEventTime() - mDownTimeStampMillis
                                     > FASTSCROLL_THRESHOLD_MILLIS)) {
                         calcTouchOffsetAndPrepToFastScroll(mDownY, mLastY);
                     }
                 }
                 if (mIsDragging) {
                     updateFastScrollSectionNameAndThumbOffset(y);
                 }
                 break;
             case MotionEvent.ACTION_UP:
             case MotionEvent.ACTION_CANCEL:
                 mRv.onFastScrollCompleted();
                 mTouchOffsetY = 0;
                 mLastTouchY = 0;
                 mIgnoreDragGesture = false;
                 if (mIsDragging) {
                     mIsDragging = false;
                     animatePopupVisibility(false);
                     showActiveScrollbar(false);
                 }
                 break;
         }
         if (DEBUG) {
             Log.d(TAG, (ev.getAction() == MotionEvent.ACTION_DOWN ? "\n" : "")
                     + "handleTouchEvent " + MotionEvent.actionToString(ev.getAction())
                     + " (" + x + "," + y + ")" + " isDragging=" + mIsDragging
                     + " mIgnoreDragGesture=" + mIgnoreDragGesture);

         }
         return mIsDragging;
     }

     private void calcTouchOffsetAndPrepToFastScroll(int downY, int lastY) {
         mIsDragging = true;
         if (mCanThumbDetach) {
             mIsThumbDetached = true;
         }
         mTouchOffsetY += (lastY - downY);
         animatePopupVisibility(true);
         showActiveScrollbar(true);
     }

     private void updateFastScrollSectionNameAndThumbOffset(int y) {
         // Update the fastscroller section name at this touch position
         int bottom = mRv.getScrollbarTrackHeight() - mThumbHeight;
         float boundedY = (float) Math.max(0, Math.min(bottom, y - mTouchOffsetY));
         String sectionName = mRv.scrollToPositionAtProgress(boundedY / bottom);
         if (!sectionName.equals(mPopupSectionName)) {
             mPopupSectionName = sectionName;
             mPopupView.setText(sectionName);
             performHapticFeedback(CLOCK_TICK);
         }
         animatePopupVisibility(!sectionName.isEmpty());
         mLastTouchY = boundedY;
         setThumbOffsetY((int) mLastTouchY);
     }

     public void onDraw(Canvas canvas) {
         if (mThumbOffsetY < 0) {
             return;
         }
         int saveCount = canvas.save();
         canvas.translate(getWidth() / 2, mRv.getScrollBarTop());
         mThumbDrawOffset.set(getWidth() / 2, mRv.getScrollBarTop());
         // Draw the track
         float halfW = mWidth / 2;
         canvas.drawRoundRect(-halfW, 0, halfW, mRv.getScrollbarTrackHeight(),
                 mWidth, mWidth, mTrackPaint);

         canvas.translate(0, mThumbOffsetY);
         mThumbDrawOffset.y += mThumbOffsetY;
         halfW += mThumbPadding;
         float r = getScrollThumbRadius();
         mThumbBounds.set(-halfW, 0, halfW, mThumbHeight);
         canvas.drawRoundRect(mThumbBounds, r, r, mThumbPaint);
         if (Utilities.ATLEAST_Q) {
             mThumbBounds.roundOut(SYSTEM_GESTURE_EXCLUSION_RECT.get(0));
             // swiping very close to the thumb area (not just within it's bound)
             // will also prevent back gesture
             SYSTEM_GESTURE_EXCLUSION_RECT.get(0).offset(mThumbDrawOffset.x, mThumbDrawOffset.y);
             if (Utilities.ATLEAST_Q && mSystemGestureInsets != null) {
                 SYSTEM_GESTURE_EXCLUSION_RECT.get(0).left =
                         SYSTEM_GESTURE_EXCLUSION_RECT.get(0).right - mSystemGestureInsets.right;
             }
             setSystemGestureExclusionRects(SYSTEM_GESTURE_EXCLUSION_RECT);
         }
         canvas.restoreToCount(saveCount);
     }

     @Override
     @RequiresApi(Build.VERSION_CODES.Q)
     public WindowInsets onApplyWindowInsets(WindowInsets insets) {
         if (Utilities.ATLEAST_Q) {
             mSystemGestureInsets = insets.getSystemGestureInsets();
         }
         return super.onApplyWindowInsets(insets);
     }

     private float getScrollThumbRadius() {
         return mWidth + mThumbPadding + mThumbPadding;
     }

     /**
      * Animates the width of the scrollbar.
      */
     private void showActiveScrollbar(boolean isScrolling) {
         if (mWidthAnimator != null) {
             mWidthAnimator.cancel();
         }

         mWidthAnimator = ObjectAnimator.ofInt(this, TRACK_WIDTH,
                 isScrolling ? mMaxWidth : mMinWidth);
         mWidthAnimator.setDuration(SCROLL_BAR_VIS_DURATION);
         mWidthAnimator.start();
     }

     /**
      * Returns whether the specified point is inside the thumb bounds.
      */
     private boolean isNearThumb(int x, int y) {
         int offset = y - mThumbOffsetY;

         return x >= 0 && x < getWidth() && offset >= 0 && offset <= mThumbHeight;
     }

     /**
      * Returns true if AllAppsTransitionController can handle vertical motion
      * beginning at this point.
      */
     public boolean shouldBlockIntercept(int x, int y) {
         return isNearThumb(x, y);
     }

     /**
      * Returns whether the specified x position is near the scroll bar.
      */
     public boolean isNearScrollBar(int x) {
         return x >= (getWidth() - mMaxWidth) / 2 - mScrollbarLeftOffsetTouchDelegate
                 && x <= (getWidth() + mMaxWidth) / 2;
     }

     private void animatePopupVisibility(boolean visible) {
         if (mPopupVisible != visible) {
             mPopupVisible = visible;
             mPopupView.animate().cancel();
             mPopupView.animate().alpha(visible ? 1f : 0f).setDuration(visible ? 200 : 150).start();
         }
     }

     private void updatePopupY(int lastTouchY) {
         int height = mPopupView.getHeight();
         // Aligns the rounded corner of the pop up with the top of the thumb.
         float top = mRv.getScrollBarTop() + lastTouchY + (getScrollThumbRadius() / 2f)
                 - (height / 2f);
         top = Utilities.boundToRange(top, 0,
                 getTop() + mRv.getScrollBarTop() + mRv.getScrollbarTrackHeight() - height);
         mPopupView.setTranslationY(top);
     }

     public boolean isHitInParent(float x, float y, Point outOffset) {
         if (mThumbOffsetY < 0) {
             return false;
         }
         getHitRect(sTempRect);
         if (mIsRecyclerViewFirstChildInParent) {
             sTempRect.top += mRv.getScrollBarTop();
         }
         if (outOffset != null) {
             outOffset.set(sTempRect.left, sTempRect.top);
         }
         return sTempRect.contains((int) x, (int) y);
     }

     @Override
     public boolean hasOverlappingRendering() {
         // There is actually some overlap between the track and the thumb. But since the track
         // alpha is so low, it does not matter.
         return false;
     }

     public void setIsRecyclerViewFirstChildInParent(boolean isRecyclerViewFirstChildInParent) {
         mIsRecyclerViewFirstChildInParent = isRecyclerViewFirstChildInParent;
     }

     public void setOnFastScrollChangeListener(
             @Nullable OnFastScrollChangeListener onFastScrollChangeListener) {
         mOnFastScrollChangeListener = onFastScrollChangeListener;
     }

     private void notifyScrollChanged() {
         if (mOnFastScrollChangeListener != null) {
             mOnFastScrollChangeListener.onScrollChanged();
         }
     }

     /**
      * A callback that is invoked when there is a scroll change in {@link RecyclerViewFastScroller}.
      */
     public interface OnFastScrollChangeListener {
         /** Called when the recycler view scroll has changed. */
         void onScrollChanged();
     }
 }
	/*
	* 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.launcher3.views;

	import static android.view.HapticFeedbackConstants.CLOCK_TICK;

	import static androidx.recyclerview.widget.RecyclerView.SCROLL_STATE_IDLE;

	import android.animation.ObjectAnimator;
	import android.content.Context;
	import android.content.res.Resources;
	import android.content.res.TypedArray;
	import android.graphics.Canvas;
	import android.graphics.Insets;
	import android.graphics.Paint;
	import android.graphics.Point;
	import android.graphics.Rect;
	import android.graphics.RectF;
	import android.os.Build;
	import android.util.AttributeSet;
	import android.util.Log;
	import android.util.Property;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewConfiguration;
	import android.view.WindowInsets;
	import android.widget.TextView;

	import androidx.annotation.Nullable;
	import androidx.annotation.RequiresApi;
	import androidx.recyclerview.widget.RecyclerView;

	import com.android.launcher3.BaseRecyclerView;
	import com.android.launcher3.R;
	import com.android.launcher3.Utilities;
	import com.android.launcher3.graphics.FastScrollThumbDrawable;
	import com.android.launcher3.util.Themes;

	import java.util.Collections;
	import java.util.List;

	/**
	* The track and scrollbar that shows when you scroll the list.
	*/
	public class RecyclerViewFastScroller extends View {
	private static final String TAG = "RecyclerViewFastScroller";
	private static final boolean DEBUG = false;
	private static final int FASTSCROLL_THRESHOLD_MILLIS = 40;
	private static final int SCROLL_DELTA_THRESHOLD_DP = 4;

	// Track is very narrow to target and correctly. This is especially the case if a user is
	// using a hardware case. Even if x is offset by following amount, we consider it to be valid.
	private static final int SCROLLBAR_LEFT_OFFSET_TOUCH_DELEGATE_DP = 5;
	private static final Rect sTempRect = new Rect();

	private static final Property<RecyclerViewFastScroller, Integer> TRACK_WIDTH =
	new Property<RecyclerViewFastScroller, Integer>(Integer.class, "width") {

	@Override
	public Integer get(RecyclerViewFastScroller scrollBar) {
	return scrollBar.mWidth;
	}

	@Override
	public void set(RecyclerViewFastScroller scrollBar, Integer value) {
	scrollBar.setTrackWidth(value);
	}
	};

	private final static int MAX_TRACK_ALPHA = 30;
	private final static int SCROLL_BAR_VIS_DURATION = 150;

	private static final List<Rect> SYSTEM_GESTURE_EXCLUSION_RECT =
	Collections.singletonList(new Rect());

	private final int mMinWidth;
	private final int mMaxWidth;
	private final int mThumbPadding;

	/** Keeps the last known scrolling delta/velocity along y-axis. */
	private int mDy = 0;
	private final float mDeltaThreshold;
	private final float mScrollbarLeftOffsetTouchDelegate;

	private final ViewConfiguration mConfig;

	// Current width of the track
	private int mWidth;
	private ObjectAnimator mWidthAnimator;

	private final Paint mThumbPaint;
	protected final int mThumbHeight;
	private final RectF mThumbBounds = new RectF();
	private final Point mThumbDrawOffset = new Point();

	private final Paint mTrackPaint;

	private float mLastTouchY;
	private boolean mIsDragging;
	private boolean mIsThumbDetached;
	private final boolean mCanThumbDetach;
	private boolean mIgnoreDragGesture;
	private boolean mIsRecyclerViewFirstChildInParent = true;
	private long mDownTimeStampMillis;

	// This is the offset from the top of the scrollbar when the user first starts touching. To
	// prevent jumping, this offset is applied as the user scrolls.
	protected int mTouchOffsetY;
	protected int mThumbOffsetY;
	protected int mRvOffsetY;

	// Fast scroller popup
	private TextView mPopupView;
	private boolean mPopupVisible;
	private String mPopupSectionName;
	private Insets mSystemGestureInsets;

	protected BaseRecyclerView mRv;
	private RecyclerView.OnScrollListener mOnScrollListener;
	@Nullable private OnFastScrollChangeListener mOnFastScrollChangeListener;

	private int mDownX;
	private int mDownY;
	private int mLastY;

	public RecyclerViewFastScroller(Context context) {
	this(context, null);
	}

	public RecyclerViewFastScroller(Context context, AttributeSet attrs) {
	this(context, attrs, 0);
	}

	public RecyclerViewFastScroller(Context context, AttributeSet attrs, int defStyleAttr) {
	super(context, attrs, defStyleAttr);

	mTrackPaint = new Paint();
	mTrackPaint.setColor(Themes.getAttrColor(context, android.R.attr.textColorPrimary));
	mTrackPaint.setAlpha(MAX_TRACK_ALPHA);

	mThumbPaint = new Paint();
	mThumbPaint.setAntiAlias(true);
	mThumbPaint.setColor(Themes.getColorAccent(context));
	mThumbPaint.setStyle(Paint.Style.FILL);

	Resources res = getResources();
	mWidth = mMinWidth = res.getDimensionPixelSize(R.dimen.fastscroll_track_min_width);
	mMaxWidth = res.getDimensionPixelSize(R.dimen.fastscroll_track_max_width);

	mThumbPadding = res.getDimensionPixelSize(R.dimen.fastscroll_thumb_padding);
	mThumbHeight = res.getDimensionPixelSize(R.dimen.fastscroll_thumb_height);

	mConfig = ViewConfiguration.get(context);
	mDeltaThreshold = res.getDisplayMetrics().density * SCROLL_DELTA_THRESHOLD_DP;
	mScrollbarLeftOffsetTouchDelegate = res.getDisplayMetrics().density
	* SCROLLBAR_LEFT_OFFSET_TOUCH_DELEGATE_DP;

	TypedArray ta =
	context.obtainStyledAttributes(attrs, R.styleable.RecyclerViewFastScroller, defStyleAttr, 0);
	mCanThumbDetach = ta.getBoolean(R.styleable.RecyclerViewFastScroller_canThumbDetach, false);
	ta.recycle();
	}

	public void setRecyclerView(BaseRecyclerView rv, TextView popupView) {
	if (mRv != null && mOnScrollListener != null) {
	mRv.removeOnScrollListener(mOnScrollListener);
	}
	mRv = rv;

	mRv.addOnScrollListener(mOnScrollListener = new RecyclerView.OnScrollListener() {
	@Override
	public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
	mDy = dy;

	// TODO(winsonc): If we want to animate the section heads while scrolling, we can
	// initiate that here if the recycler view scroll state is not
	// RecyclerView.SCROLL_STATE_IDLE.

	mRv.onUpdateScrollbar(dy);
	}
	});

	mPopupView = popupView;
	mPopupView.setBackground(
	new FastScrollThumbDrawable(mThumbPaint, Utilities.isRtl(getResources())));
	}

	public void reattachThumbToScroll() {
	mIsThumbDetached = false;
	}

	public void setThumbOffsetY(int y) {
	if (mThumbOffsetY == y) {
	int rvCurrentOffsetY = mRv.getCurrentScrollY();
	if (mRvOffsetY != rvCurrentOffsetY) {
	mRvOffsetY = mRv.getCurrentScrollY();
	notifyScrollChanged();
	}
	return;
	}
	updatePopupY(y);
	mThumbOffsetY = y;
	invalidate();
	mRvOffsetY = mRv.getCurrentScrollY();
	notifyScrollChanged();
	}

	public int getThumbOffsetY() {
	return mThumbOffsetY;
	}

	private void setTrackWidth(int width) {
	if (mWidth == width) {
	return;
	}
	mWidth = width;
	invalidate();
	}

	public int getThumbHeight() {
	return mThumbHeight;
	}

	public boolean isDraggingThumb() {
	return mIsDragging;
	}

	public boolean isThumbDetached() {
	return mIsThumbDetached;
	}

	/**
	* Handles the touch event and determines whether to show the fast scroller (or updates it if
	* it is already showing).
	*/
	public boolean handleTouchEvent(MotionEvent ev, Point offset) {
	int x = (int) ev.getX() - offset.x;
	int y = (int) ev.getY() - offset.y;

	switch (ev.getAction()) {
	case MotionEvent.ACTION_DOWN:
	// Keep track of the down positions
	mDownX = x;
	mDownY = mLastY = y;
	mDownTimeStampMillis = ev.getDownTime();

	if ((Math.abs(mDy) < mDeltaThreshold &&
	mRv.getScrollState() != SCROLL_STATE_IDLE)) {
	// now the touch events are being passed to the {@link WidgetCell} until the
	// touch sequence goes over the touch slop.
	mRv.stopScroll();
	}
	if (isNearThumb(x, y)) {
	mTouchOffsetY = mDownY - mThumbOffsetY;
	}
	break;
	case MotionEvent.ACTION_MOVE:
	mLastY = y;
	int absDeltaY = Math.abs(y - mDownY);
	int absDeltaX = Math.abs(x - mDownX);

	// Check if we should start scrolling, but ignore this fastscroll gesture if we have
	// exceeded some fixed movement
	mIgnoreDragGesture \|= absDeltaY > mConfig.getScaledPagingTouchSlop();

	if (!mIsDragging && !mIgnoreDragGesture && mRv.supportsFastScrolling()) {
	if ((isNearThumb(mDownX, mLastY) && ev.getEventTime() - mDownTimeStampMillis
	> FASTSCROLL_THRESHOLD_MILLIS)) {
	calcTouchOffsetAndPrepToFastScroll(mDownY, mLastY);
	}
	}
	if (mIsDragging) {
	updateFastScrollSectionNameAndThumbOffset(y);
	}
	break;
	case MotionEvent.ACTION_UP:
	case MotionEvent.ACTION_CANCEL:
	mRv.onFastScrollCompleted();
	mTouchOffsetY = 0;
	mLastTouchY = 0;
	mIgnoreDragGesture = false;
	if (mIsDragging) {
	mIsDragging = false;
	animatePopupVisibility(false);
	showActiveScrollbar(false);
	}
	break;
	}
	if (DEBUG) {
	Log.d(TAG, (ev.getAction() == MotionEvent.ACTION_DOWN ? "\n" : "")
	+ "handleTouchEvent " + MotionEvent.actionToString(ev.getAction())
	+ " (" + x + "," + y + ")" + " isDragging=" + mIsDragging
	+ " mIgnoreDragGesture=" + mIgnoreDragGesture);

	}
	return mIsDragging;
	}

	private void calcTouchOffsetAndPrepToFastScroll(int downY, int lastY) {
	mIsDragging = true;
	if (mCanThumbDetach) {
	mIsThumbDetached = true;
	}
	mTouchOffsetY += (lastY - downY);
	animatePopupVisibility(true);
	showActiveScrollbar(true);
	}

	private void updateFastScrollSectionNameAndThumbOffset(int y) {
	// Update the fastscroller section name at this touch position
	int bottom = mRv.getScrollbarTrackHeight() - mThumbHeight;
	float boundedY = (float) Math.max(0, Math.min(bottom, y - mTouchOffsetY));
	String sectionName = mRv.scrollToPositionAtProgress(boundedY / bottom);
	if (!sectionName.equals(mPopupSectionName)) {
	mPopupSectionName = sectionName;
	mPopupView.setText(sectionName);
	performHapticFeedback(CLOCK_TICK);
	}
	animatePopupVisibility(!sectionName.isEmpty());
	mLastTouchY = boundedY;
	setThumbOffsetY((int) mLastTouchY);
	}

	public void onDraw(Canvas canvas) {
	if (mThumbOffsetY < 0) {
	return;
	}
	int saveCount = canvas.save();
	canvas.translate(getWidth() / 2, mRv.getScrollBarTop());
	mThumbDrawOffset.set(getWidth() / 2, mRv.getScrollBarTop());
	// Draw the track
	float halfW = mWidth / 2;
	canvas.drawRoundRect(-halfW, 0, halfW, mRv.getScrollbarTrackHeight(),
	mWidth, mWidth, mTrackPaint);

	canvas.translate(0, mThumbOffsetY);
	mThumbDrawOffset.y += mThumbOffsetY;
	halfW += mThumbPadding;
	float r = getScrollThumbRadius();
	mThumbBounds.set(-halfW, 0, halfW, mThumbHeight);
	canvas.drawRoundRect(mThumbBounds, r, r, mThumbPaint);
	if (Utilities.ATLEAST_Q) {
	mThumbBounds.roundOut(SYSTEM_GESTURE_EXCLUSION_RECT.get(0));
	// swiping very close to the thumb area (not just within it's bound)
	// will also prevent back gesture
	SYSTEM_GESTURE_EXCLUSION_RECT.get(0).offset(mThumbDrawOffset.x, mThumbDrawOffset.y);
	if (Utilities.ATLEAST_Q && mSystemGestureInsets != null) {
	SYSTEM_GESTURE_EXCLUSION_RECT.get(0).left =
	SYSTEM_GESTURE_EXCLUSION_RECT.get(0).right - mSystemGestureInsets.right;
	}
	setSystemGestureExclusionRects(SYSTEM_GESTURE_EXCLUSION_RECT);
	}
	canvas.restoreToCount(saveCount);
	}

	@Override
	@RequiresApi(Build.VERSION_CODES.Q)
	public WindowInsets onApplyWindowInsets(WindowInsets insets) {
	if (Utilities.ATLEAST_Q) {
	mSystemGestureInsets = insets.getSystemGestureInsets();
	}
	return super.onApplyWindowInsets(insets);
	}

	private float getScrollThumbRadius() {
	return mWidth + mThumbPadding + mThumbPadding;
	}

	/**
	* Animates the width of the scrollbar.
	*/
	private void showActiveScrollbar(boolean isScrolling) {
	if (mWidthAnimator != null) {
	mWidthAnimator.cancel();
	}

	mWidthAnimator = ObjectAnimator.ofInt(this, TRACK_WIDTH,
	isScrolling ? mMaxWidth : mMinWidth);
	mWidthAnimator.setDuration(SCROLL_BAR_VIS_DURATION);
	mWidthAnimator.start();
	}

	/**
	* Returns whether the specified point is inside the thumb bounds.
	*/
	private boolean isNearThumb(int x, int y) {
	int offset = y - mThumbOffsetY;

	return x >= 0 && x < getWidth() && offset >= 0 && offset <= mThumbHeight;
	}

	/**
	* Returns true if AllAppsTransitionController can handle vertical motion
	* beginning at this point.
	*/
	public boolean shouldBlockIntercept(int x, int y) {
	return isNearThumb(x, y);
	}

	/**
	* Returns whether the specified x position is near the scroll bar.
	*/
	public boolean isNearScrollBar(int x) {
	return x >= (getWidth() - mMaxWidth) / 2 - mScrollbarLeftOffsetTouchDelegate
	&& x <= (getWidth() + mMaxWidth) / 2;
	}

	private void animatePopupVisibility(boolean visible) {
	if (mPopupVisible != visible) {
	mPopupVisible = visible;
	mPopupView.animate().cancel();
	mPopupView.animate().alpha(visible ? 1f : 0f).setDuration(visible ? 200 : 150).start();
	}
	}

	private void updatePopupY(int lastTouchY) {
	int height = mPopupView.getHeight();
	// Aligns the rounded corner of the pop up with the top of the thumb.
	float top = mRv.getScrollBarTop() + lastTouchY + (getScrollThumbRadius() / 2f)
	- (height / 2f);
	top = Utilities.boundToRange(top, 0,
	getTop() + mRv.getScrollBarTop() + mRv.getScrollbarTrackHeight() - height);
	mPopupView.setTranslationY(top);
	}

	public boolean isHitInParent(float x, float y, Point outOffset) {
	if (mThumbOffsetY < 0) {
	return false;
	}
	getHitRect(sTempRect);
	if (mIsRecyclerViewFirstChildInParent) {
	sTempRect.top += mRv.getScrollBarTop();
	}
	if (outOffset != null) {
	outOffset.set(sTempRect.left, sTempRect.top);
	}
	return sTempRect.contains((int) x, (int) y);
	}

	@Override
	public boolean hasOverlappingRendering() {
	// There is actually some overlap between the track and the thumb. But since the track
	// alpha is so low, it does not matter.
	return false;
	}

	public void setIsRecyclerViewFirstChildInParent(boolean isRecyclerViewFirstChildInParent) {
	mIsRecyclerViewFirstChildInParent = isRecyclerViewFirstChildInParent;
	}

	public void setOnFastScrollChangeListener(
	@Nullable OnFastScrollChangeListener onFastScrollChangeListener) {
	mOnFastScrollChangeListener = onFastScrollChangeListener;
	}

	private void notifyScrollChanged() {
	if (mOnFastScrollChangeListener != null) {
	mOnFastScrollChangeListener.onScrollChanged();
	}
	}

	/**
	* A callback that is invoked when there is a scroll change in {@link RecyclerViewFastScroller}.
	*/
	public interface OnFastScrollChangeListener {
	/** Called when the recycler view scroll has changed. */
	void onScrollChanged();
	}
	}