FileDocCategorySizeDatePackage
FastScroller.javaAPI DocAndroid 5.1 API58835Thu Mar 12 22:22:10 GMT 2015android.widget

FastScroller

public class FastScroller extends Object
Helper class for AbsListView to draw and control the Fast Scroll thumb

Fields Summary
private static final int
DURATION_FADE_OUT
Duration of fade-out animation.
private static final int
DURATION_FADE_IN
Duration of fade-in animation.
private static final int
DURATION_CROSS_FADE
Duration of transition cross-fade animation.
private static final int
DURATION_RESIZE
Duration of transition resize animation.
private static final long
FADE_TIMEOUT
Inactivity timeout before fading controls.
private static final int
MIN_PAGES
Minimum number of pages to justify showing a fast scroll thumb.
private static final int
STATE_NONE
Scroll thumb and preview not showing.
private static final int
STATE_VISIBLE
Scroll thumb visible and moving along with the scrollbar.
private static final int
STATE_DRAGGING
Scroll thumb and preview being dragged by user.
private static final int
OVERLAY_FLOATING
private static final int
OVERLAY_AT_THUMB
private static final int
OVERLAY_ABOVE_THUMB
private static final int
PREVIEW_LEFT
private static final int
PREVIEW_RIGHT
private static final long
TAP_TIMEOUT
Delay before considering a tap in the thumb area to be a drag.
private final android.graphics.Rect
mTempBounds
private final android.graphics.Rect
mTempMargins
private final android.graphics.Rect
mContainerRect
private final AbsListView
mList
private final android.view.ViewGroupOverlay
mOverlay
private final TextView
mPrimaryText
private final TextView
mSecondaryText
private final ImageView
mThumbImage
private final ImageView
mTrackImage
private final android.view.View
mPreviewImage
private final int[]
mPreviewResId
Preview image resource IDs for left- and right-aligned layouts. See {@link #PREVIEW_LEFT} and {@link #PREVIEW_RIGHT}.
private final int
mMinimumTouchTarget
The minimum touch target size in pixels.
private int
mPreviewPadding
Padding in pixels around the preview text. Applied as layout margins to the preview text and padding to the preview image.
private int
mPreviewMinWidth
private int
mPreviewMinHeight
private int
mThumbMinWidth
private int
mThumbMinHeight
private float
mTextSize
Theme-specified text size. Used only if text appearance is not set.
private android.content.res.ColorStateList
mTextColor
Theme-specified text color. Used only if text appearance is not set.
private android.graphics.drawable.Drawable
mThumbDrawable
private android.graphics.drawable.Drawable
mTrackDrawable
private int
mTextAppearance
private int
mWidth
Total width of decorations.
private android.animation.AnimatorSet
mDecorAnimation
Set containing decoration transition animations.
private android.animation.AnimatorSet
mPreviewAnimation
Set containing preview text transition animations.
private boolean
mShowingPrimary
Whether the primary text is showing.
private boolean
mScrollCompleted
Whether we're waiting for completion of scrollTo().
private int
mFirstVisibleItem
The position of the first visible item in the list.
private int
mHeaderCount
The number of headers at the top of the view.
private int
mCurrentSection
The index of the current section.
private int
mScrollbarPosition
The current scrollbar position.
private boolean
mLongList
Whether the list is long enough to need a fast scroller.
private Object[]
mSections
private boolean
mUpdatingLayout
Whether this view is currently performing layout.
private int
mState
Current decoration state, one of:
  • {@link #STATE_NONE}, nothing visible
  • {@link #STATE_VISIBLE}, showing track and thumb
  • {@link #STATE_DRAGGING}, visible and showing preview
private boolean
mShowingPreview
Whether the preview image is visible.
private Adapter
mListAdapter
private SectionIndexer
mSectionIndexer
private boolean
mLayoutFromRight
Whether decorations should be laid out from right to left.
private boolean
mEnabled
Whether the fast scroller is enabled.
private boolean
mAlwaysShow
Whether the scrollbar and decorations should always be shown.
private int
mOverlayPosition
Position for the preview image and text. One of:
  • {@link #OVERLAY_FLOATING}
  • {@link #OVERLAY_AT_THUMB}
  • {@link #OVERLAY_ABOVE_THUMB}
private int
mScrollBarStyle
Current scrollbar style, including inset and overlay properties.
private boolean
mMatchDragPosition
Whether to precisely match the thumb position to the list.
private float
mInitialTouchY
private long
mPendingDrag
private int
mScaledTouchSlop
private int
mOldItemCount
private int
mOldChildCount
private final Runnable
mDeferHide
Used to delay hiding fast scroll decorations.
private final android.animation.Animator.AnimatorListener
mSwitchPrimaryListener
Used to effect a transition from primary to secondary text.
private static android.util.Property
LEFT
A Property wrapper around the left functionality handled by the {@link View#setLeft(int)} and {@link View#getLeft()} methods.
private static android.util.Property
TOP
A Property wrapper around the top functionality handled by the {@link View#setTop(int)} and {@link View#getTop()} methods.
private static android.util.Property
RIGHT
A Property wrapper around the right functionality handled by the {@link View#setRight(int)} and {@link View#getRight()} methods.
private static android.util.Property
BOTTOM
A Property wrapper around the bottom functionality handled by the {@link View#setBottom(int)} and {@link View#getBottom()} methods.
Constructors Summary
public FastScroller(AbsListView listView, int styleResId)


         
        mList = listView;
        mOldItemCount = listView.getCount();
        mOldChildCount = listView.getChildCount();

        final Context context = listView.getContext();
        mScaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
        mScrollBarStyle = listView.getScrollBarStyle();

        mScrollCompleted = true;
        mState = STATE_VISIBLE;
        mMatchDragPosition =
                context.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.HONEYCOMB;

        mTrackImage = new ImageView(context);
        mTrackImage.setScaleType(ScaleType.FIT_XY);
        mThumbImage = new ImageView(context);
        mThumbImage.setScaleType(ScaleType.FIT_XY);
        mPreviewImage = new View(context);
        mPreviewImage.setAlpha(0f);

        mPrimaryText = createPreviewTextView(context);
        mSecondaryText = createPreviewTextView(context);

        mMinimumTouchTarget = listView.getResources().getDimensionPixelSize(
                com.android.internal.R.dimen.fast_scroller_minimum_touch_target);

        setStyle(styleResId);

        final ViewGroupOverlay overlay = listView.getOverlay();
        mOverlay = overlay;
        overlay.add(mTrackImage);
        overlay.add(mThumbImage);
        overlay.add(mPreviewImage);
        overlay.add(mPrimaryText);
        overlay.add(mSecondaryText);

        getSectionsFromIndexer();
        updateLongList(mOldChildCount, mOldItemCount);
        setScrollbarPosition(listView.getVerticalScrollbarPosition());
        postAutoHide();
Methods Summary
private static android.animation.AnimatoranimateAlpha(android.view.View v, float alpha)
Returns an animator for the view's alpha value.

        return ObjectAnimator.ofFloat(v, View.ALPHA, alpha);
private static android.animation.AnimatoranimateBounds(android.view.View v, android.graphics.Rect bounds)
Returns an animator for the view's bounds.


                
           
        final PropertyValuesHolder left = PropertyValuesHolder.ofInt(LEFT, bounds.left);
        final PropertyValuesHolder top = PropertyValuesHolder.ofInt(TOP, bounds.top);
        final PropertyValuesHolder right = PropertyValuesHolder.ofInt(RIGHT, bounds.right);
        final PropertyValuesHolder bottom = PropertyValuesHolder.ofInt(BOTTOM, bounds.bottom);
        return ObjectAnimator.ofPropertyValuesHolder(v, left, top, right, bottom);
private static android.animation.AnimatoranimateScaleX(android.view.View v, float target)
Returns an animator for the view's scaleX value.

        return ObjectAnimator.ofFloat(v, View.SCALE_X, target);
private voidapplyLayout(android.view.View view, android.graphics.Rect bounds)
Layouts a view within the specified bounds and pins the pivot point to the appropriate edge.

param
view The view to layout.
param
bounds Bounds at which to layout the view.

        view.layout(bounds.left, bounds.top, bounds.right, bounds.bottom);
        view.setPivotX(mLayoutFromRight ? bounds.right - bounds.left : 0);
private voidbeginDrag()

        mPendingDrag = -1;

        setState(STATE_DRAGGING);

        if (mListAdapter == null && mList != null) {
            getSectionsFromIndexer();
        }

        if (mList != null) {
            mList.requestDisallowInterceptTouchEvent(true);
            mList.reportScrollStateChange(OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
        }

        cancelFling();
private voidcancelFling()
Cancels an ongoing fling event by injecting a {@link MotionEvent#ACTION_CANCEL} into the host view.

        final MotionEvent cancelFling = MotionEvent.obtain(
                0, 0, MotionEvent.ACTION_CANCEL, 0, 0, 0);
        mList.onTouchEvent(cancelFling);
        cancelFling.recycle();
private voidcancelPendingDrag()
Cancels a pending drag.

see
#startPendingDrag()

        mPendingDrag = -1;
private TextViewcreatePreviewTextView(android.content.Context context)
Creates a view into which preview text can be placed.

        final LayoutParams params = new LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        final TextView textView = new TextView(context);
        textView.setLayoutParams(params);
        textView.setSingleLine(true);
        textView.setEllipsize(TruncateAt.MIDDLE);
        textView.setGravity(Gravity.CENTER);
        textView.setAlpha(0f);

        // Manually propagate inherited layout direction.
        textView.setLayoutDirection(mList.getLayoutDirection());

        return textView;
private floatgetPosFromItemCount(int firstVisibleItem, int visibleItemCount, int totalItemCount)
Calculates the thumb position based on the visible items.

param
firstVisibleItem First visible item, >= 0.
param
visibleItemCount Number of visible items, >= 0.
param
totalItemCount Total number of items, >= 0.
return

        final SectionIndexer sectionIndexer = mSectionIndexer;
        if (sectionIndexer == null || mListAdapter == null) {
            getSectionsFromIndexer();
        }

        if (visibleItemCount == 0 || totalItemCount == 0) {
            // No items are visible.
            return 0;
        }

        final boolean hasSections = sectionIndexer != null && mSections != null
                && mSections.length > 0;
        if (!hasSections || !mMatchDragPosition) {
            if (visibleItemCount == totalItemCount) {
                // All items are visible.
                return 0;
            } else {
                return (float) firstVisibleItem / (totalItemCount - visibleItemCount);
            }
        }

        // Ignore headers.
        firstVisibleItem -= mHeaderCount;
        if (firstVisibleItem < 0) {
            return 0;
        }
        totalItemCount -= mHeaderCount;

        // Hidden portion of the first visible row.
        final View child = mList.getChildAt(0);
        final float incrementalPos;
        if (child == null || child.getHeight() == 0) {
            incrementalPos = 0;
        } else {
            incrementalPos = (float) (mList.getPaddingTop() - child.getTop()) / child.getHeight();
        }

        // Number of rows in this section.
        final int section = sectionIndexer.getSectionForPosition(firstVisibleItem);
        final int sectionPos = sectionIndexer.getPositionForSection(section);
        final int sectionCount = mSections.length;
        final int positionsInSection;
        if (section < sectionCount - 1) {
            final int nextSectionPos;
            if (section + 1 < sectionCount) {
                nextSectionPos = sectionIndexer.getPositionForSection(section + 1);
            } else {
                nextSectionPos = totalItemCount - 1;
            }
            positionsInSection = nextSectionPos - sectionPos;
        } else {
            positionsInSection = totalItemCount - sectionPos;
        }

        // Position within this section.
        final float posWithinSection;
        if (positionsInSection == 0) {
            posWithinSection = 0;
        } else {
            posWithinSection = (firstVisibleItem + incrementalPos - sectionPos)
                    / positionsInSection;
        }

        float result = (section + posWithinSection) / sectionCount;

        // Fake out the scroll bar for the last item. Since the section indexer
        // won't ever actually move the list in this end space, make scrolling
        // across the last item account for whatever space is remaining.
        if (firstVisibleItem > 0 && firstVisibleItem + visibleItemCount == totalItemCount) {
            final View lastChild = mList.getChildAt(visibleItemCount - 1);
            final int bottomPadding = mList.getPaddingBottom();
            final int maxSize;
            final int currentVisibleSize;
            if (mList.getClipToPadding()) {
                maxSize = lastChild.getHeight();
                currentVisibleSize = mList.getHeight() - bottomPadding - lastChild.getTop();
            } else {
                maxSize = lastChild.getHeight() + bottomPadding;
                currentVisibleSize = mList.getHeight() - lastChild.getTop();
            }
            if (currentVisibleSize > 0 && maxSize > 0) {
                result += (1 - result) * ((float) currentVisibleSize / maxSize );
            }
        }

        return result;
private floatgetPosFromMotionEvent(float y)

        final View trackImage = mTrackImage;
        final float min = trackImage.getTop();
        final float max = trackImage.getBottom();
        final float offset = min;
        final float range = max - min;

        // If the list is the same height as the thumbnail or shorter,
        // effectively disable scrolling.
        if (range <= 0) {
            return 0f;
        }

        return MathUtils.constrain((y - offset) / range, 0f, 1f);
private voidgetSectionsFromIndexer()

        mSectionIndexer = null;

        Adapter adapter = mList.getAdapter();
        if (adapter instanceof HeaderViewListAdapter) {
            mHeaderCount = ((HeaderViewListAdapter) adapter).getHeadersCount();
            adapter = ((HeaderViewListAdapter) adapter).getWrappedAdapter();
        }

        if (adapter instanceof ExpandableListConnector) {
            final ExpandableListAdapter expAdapter = ((ExpandableListConnector) adapter)
                    .getAdapter();
            if (expAdapter instanceof SectionIndexer) {
                mSectionIndexer = (SectionIndexer) expAdapter;
                mListAdapter = adapter;
                mSections = mSectionIndexer.getSections();
            }
        } else if (adapter instanceof SectionIndexer) {
            mListAdapter = adapter;
            mSectionIndexer = (SectionIndexer) adapter;
            mSections = mSectionIndexer.getSections();
        } else {
            mListAdapter = adapter;
            mSections = null;
        }
public intgetWidth()

        return mWidth;
private static android.animation.AnimatorgroupAnimatorOfFloat(android.util.Property property, float value, android.view.View views)
Constructs an animator for the specified property on a group of views. See {@link ObjectAnimator#ofFloat(Object, String, float...)} for implementation details.

param
property The property being animated.
param
value The value to which that property should animate.
param
views The target views to animate.
return
An animator for all the specified views.

        AnimatorSet animSet = new AnimatorSet();
        AnimatorSet.Builder builder = null;

        for (int i = views.length - 1; i >= 0; i--) {
            final Animator anim = ObjectAnimator.ofFloat(views[i], property, value);
            if (builder == null) {
                builder = animSet.play(anim);
            } else {
                builder.with(anim);
            }
        }

        return animSet;
public booleanisAlwaysShowEnabled()

return
Whether the fast scroll thumb will always be shown
see
#setAlwaysShow(boolean)

        return mAlwaysShow;
public booleanisEnabled()

return
Whether the fast scroll thumb is enabled.

        return mEnabled && (mLongList || mAlwaysShow);
private booleanisPointInside(float x, float y)
Returns whether a coordinate is inside the scroller's activation area. If there is a track image, touching anywhere within the thumb-width of the track activates scrolling. Otherwise, the user has to touch inside thumb itself.

param
x The x-coordinate.
param
y The y-coordinate.
return
Whether the coordinate is inside the scroller's activation area.

        return isPointInsideX(x) && (mTrackDrawable != null || isPointInsideY(y));
private booleanisPointInsideX(float x)

        final float offset = mThumbImage.getTranslationX();
        final float left = mThumbImage.getLeft() + offset;
        final float right = mThumbImage.getRight() + offset;

        // Apply the minimum touch target size.
        final float targetSizeDiff = mMinimumTouchTarget - (right - left);
        final float adjust = targetSizeDiff > 0 ? targetSizeDiff : 0;

        if (mLayoutFromRight) {
            return x >= mThumbImage.getLeft() - adjust;
        } else {
            return x <= mThumbImage.getRight() + adjust;
        }
private booleanisPointInsideY(float y)

        final float offset = mThumbImage.getTranslationY();
        final float top = mThumbImage.getTop() + offset;
        final float bottom = mThumbImage.getBottom() + offset;

        // Apply the minimum touch target size.
        final float targetSizeDiff = mMinimumTouchTarget - (bottom - top);
        final float adjust = targetSizeDiff > 0 ? targetSizeDiff / 2 : 0;

        return y >= (top - adjust) && y <= (bottom + adjust);
private voidlayoutThumb()
Lays out the thumb according to the current scrollbar position.

        final Rect bounds = mTempBounds;
        measureViewToSide(mThumbImage, null, null, bounds);
        applyLayout(mThumbImage, bounds);
private voidlayoutTrack()
Lays out the track centered on the thumb. Must be called after {@link #layoutThumb}.

        final View track = mTrackImage;
        final View thumb = mThumbImage;
        final Rect container = mContainerRect;
        final int containerWidth = container.width();
        final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(containerWidth, MeasureSpec.AT_MOST);
        final int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        track.measure(widthMeasureSpec, heightMeasureSpec);

        final int trackWidth = track.getMeasuredWidth();
        final int thumbHalfHeight = thumb == null ? 0 : thumb.getHeight() / 2;
        final int left = thumb.getLeft() + (thumb.getWidth() - trackWidth) / 2;
        final int right = left + trackWidth;
        final int top = container.top + thumbHalfHeight;
        final int bottom = container.bottom - thumbHalfHeight;
        track.layout(left, top, right, bottom);
private voidmeasureFloating(android.view.View preview, android.graphics.Rect margins, android.graphics.Rect out)

        final int marginLeft;
        final int marginTop;
        final int marginRight;
        if (margins == null) {
            marginLeft = 0;
            marginTop = 0;
            marginRight = 0;
        } else {
            marginLeft = margins.left;
            marginTop = margins.top;
            marginRight = margins.right;
        }

        final Rect container = mContainerRect;
        final int containerWidth = container.width();
        final int adjMaxWidth = containerWidth - marginLeft - marginRight;
        final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(adjMaxWidth, MeasureSpec.AT_MOST);
        final int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        preview.measure(widthMeasureSpec, heightMeasureSpec);

        // Align at the vertical center, 10% from the top.
        final int containerHeight = container.height();
        final int width = preview.getMeasuredWidth();
        final int top = containerHeight / 10 + marginTop + container.top;
        final int bottom = top + preview.getMeasuredHeight();
        final int left = (containerWidth - width) / 2 + container.left;
        final int right = left + width;
        out.set(left, top, right, bottom);
private voidmeasurePreview(android.view.View v, android.graphics.Rect out)
Measures the preview text bounds, taking preview image padding into account. This method should only be called after {@link #layoutThumb()} and {@link #layoutTrack()} have both been called at least once.

param
v The preview text view to measure.
param
out Rectangle into which measured bounds are placed.

        // Apply the preview image's padding as layout margins.
        final Rect margins = mTempMargins;
        margins.left = mPreviewImage.getPaddingLeft();
        margins.top = mPreviewImage.getPaddingTop();
        margins.right = mPreviewImage.getPaddingRight();
        margins.bottom = mPreviewImage.getPaddingBottom();

        if (mOverlayPosition == OVERLAY_FLOATING) {
            measureFloating(v, margins, out);
        } else {
            measureViewToSide(v, mThumbImage, margins, out);
        }
private voidmeasureViewToSide(android.view.View view, android.view.View adjacent, android.graphics.Rect margins, android.graphics.Rect out)
Measures the bounds for a view that should be laid out against the edge of an adjacent view. If no adjacent view is provided, lays out against the list edge.

param
view The view to measure for layout.
param
adjacent (Optional) The adjacent view, may be null to align to the list edge.
param
margins Layout margins to apply to the view.
param
out Rectangle into which measured bounds are placed.

        final int marginLeft;
        final int marginTop;
        final int marginRight;
        if (margins == null) {
            marginLeft = 0;
            marginTop = 0;
            marginRight = 0;
        } else {
            marginLeft = margins.left;
            marginTop = margins.top;
            marginRight = margins.right;
        }

        final Rect container = mContainerRect;
        final int containerWidth = container.width();
        final int maxWidth;
        if (adjacent == null) {
            maxWidth = containerWidth;
        } else if (mLayoutFromRight) {
            maxWidth = adjacent.getLeft();
        } else {
            maxWidth = containerWidth - adjacent.getRight();
        }

        final int adjMaxWidth = maxWidth - marginLeft - marginRight;
        final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(adjMaxWidth, MeasureSpec.AT_MOST);
        final int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        view.measure(widthMeasureSpec, heightMeasureSpec);

        // Align to the left or right.
        final int width = Math.min(adjMaxWidth, view.getMeasuredWidth());
        final int left;
        final int right;
        if (mLayoutFromRight) {
            right = (adjacent == null ? container.right : adjacent.getLeft()) - marginRight;
            left = right - width;
        } else {
            left = (adjacent == null ? container.left : adjacent.getRight()) + marginLeft;
            right = left + width;
        }

        // Don't adjust the vertical position.
        final int top = marginTop;
        final int bottom = top + view.getMeasuredHeight();
        out.set(left, top, right, bottom);
public booleanonInterceptHoverEvent(android.view.MotionEvent ev)

        if (!isEnabled()) {
            return false;
        }

        final int actionMasked = ev.getActionMasked();
        if ((actionMasked == MotionEvent.ACTION_HOVER_ENTER
                || actionMasked == MotionEvent.ACTION_HOVER_MOVE) && mState == STATE_NONE
                && isPointInside(ev.getX(), ev.getY())) {
            setState(STATE_VISIBLE);
            postAutoHide();
        }

        return false;
public booleanonInterceptTouchEvent(android.view.MotionEvent ev)

        if (!isEnabled()) {
            return false;
        }

        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                if (isPointInside(ev.getX(), ev.getY())) {
                    // If the parent has requested that its children delay
                    // pressed state (e.g. is a scrolling container) then we
                    // need to allow the parent time to decide whether it wants
                    // to intercept events. If it does, we will receive a CANCEL
                    // event.
                    if (!mList.isInScrollingContainer()) {
                        beginDrag();
                        return true;
                    }

                    mInitialTouchY = ev.getY();
                    startPendingDrag();
                }
                break;
            case MotionEvent.ACTION_MOVE:
                if (!isPointInside(ev.getX(), ev.getY())) {
                    cancelPendingDrag();
                } else if (mPendingDrag >= 0 && mPendingDrag <= SystemClock.uptimeMillis()) {
                    beginDrag();

                    final float pos = getPosFromMotionEvent(mInitialTouchY);
                    scrollTo(pos);

                    return onTouchEvent(ev);
                }
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                cancelPendingDrag();
                break;
        }

        return false;
public voidonItemCountChanged(int childCount, int itemCount)

        if (mOldItemCount != itemCount || mOldChildCount != childCount) {
            mOldItemCount = itemCount;
            mOldChildCount = childCount;

            final boolean hasMoreItems = itemCount - childCount > 0;
            if (hasMoreItems && mState != STATE_DRAGGING) {
                final int firstVisibleItem = mList.getFirstVisiblePosition();
                setThumbPos(getPosFromItemCount(firstVisibleItem, childCount, itemCount));
            }

            updateLongList(childCount, itemCount);
        }
public voidonScroll(int firstVisibleItem, int visibleItemCount, int totalItemCount)

        if (!isEnabled()) {
            setState(STATE_NONE);
            return;
        }

        final boolean hasMoreItems = totalItemCount - visibleItemCount > 0;
        if (hasMoreItems && mState != STATE_DRAGGING) {
            setThumbPos(getPosFromItemCount(firstVisibleItem, visibleItemCount, totalItemCount));
        }

        mScrollCompleted = true;

        if (mFirstVisibleItem != firstVisibleItem) {
            mFirstVisibleItem = firstVisibleItem;

            // Show the thumb, if necessary, and set up auto-fade.
            if (mState != STATE_DRAGGING) {
                setState(STATE_VISIBLE);
                postAutoHide();
            }
        }
public voidonSectionsChanged()

        mListAdapter = null;
public voidonSizeChanged(int w, int h, int oldw, int oldh)

        updateLayout();
private voidonStateDependencyChanged(boolean peekIfEnabled)
Called when one of the variables affecting enabled state changes.

param
peekIfEnabled whether the thumb should peek, if enabled

        if (isEnabled()) {
            if (isAlwaysShowEnabled()) {
                setState(STATE_VISIBLE);
            } else if (mState == STATE_VISIBLE) {
                postAutoHide();
            } else if (peekIfEnabled) {
                setState(STATE_VISIBLE);
                postAutoHide();
            }
        } else {
            stop();
        }

        mList.resolvePadding();
public booleanonTouchEvent(android.view.MotionEvent me)

        if (!isEnabled()) {
            return false;
        }

        switch (me.getActionMasked()) {
            case MotionEvent.ACTION_UP: {
                if (mPendingDrag >= 0) {
                    // Allow a tap to scroll.
                    beginDrag();

                    final float pos = getPosFromMotionEvent(me.getY());
                    setThumbPos(pos);
                    scrollTo(pos);

                    // Will hit the STATE_DRAGGING check below
                }

                if (mState == STATE_DRAGGING) {
                    if (mList != null) {
                        // ViewGroup does the right thing already, but there might
                        // be other classes that don't properly reset on touch-up,
                        // so do this explicitly just in case.
                        mList.requestDisallowInterceptTouchEvent(false);
                        mList.reportScrollStateChange(OnScrollListener.SCROLL_STATE_IDLE);
                    }

                    setState(STATE_VISIBLE);
                    postAutoHide();

                    return true;
                }
            } break;

            case MotionEvent.ACTION_MOVE: {
                if (mPendingDrag >= 0 && Math.abs(me.getY() - mInitialTouchY) > mScaledTouchSlop) {
                    beginDrag();

                    // Will hit the STATE_DRAGGING check below
                }

                if (mState == STATE_DRAGGING) {
                    // TODO: Ignore jitter.
                    final float pos = getPosFromMotionEvent(me.getY());
                    setThumbPos(pos);

                    // If the previous scrollTo is still pending
                    if (mScrollCompleted) {
                        scrollTo(pos);
                    }

                    return true;
                }
            } break;

            case MotionEvent.ACTION_CANCEL: {
                cancelPendingDrag();
            } break;
        }

        return false;
private voidpostAutoHide()

        mList.removeCallbacks(mDeferHide);
        mList.postDelayed(mDeferHide, FADE_TIMEOUT);
private voidrefreshDrawablePressedState()

        final boolean isPressed = mState == STATE_DRAGGING;
        mThumbImage.setPressed(isPressed);
        mTrackImage.setPressed(isPressed);
public voidremove()
Removes this FastScroller overlay from the host view.

        mOverlay.remove(mTrackImage);
        mOverlay.remove(mThumbImage);
        mOverlay.remove(mPreviewImage);
        mOverlay.remove(mPrimaryText);
        mOverlay.remove(mSecondaryText);
private voidscrollTo(float position)
Scrolls to a specific position within the section

param
position

        mScrollCompleted = false;

        final int count = mList.getCount();
        final Object[] sections = mSections;
        final int sectionCount = sections == null ? 0 : sections.length;
        int sectionIndex;
        if (sections != null && sectionCount > 1) {
            final int exactSection = MathUtils.constrain(
                    (int) (position * sectionCount), 0, sectionCount - 1);
            int targetSection = exactSection;
            int targetIndex = mSectionIndexer.getPositionForSection(targetSection);
            sectionIndex = targetSection;

            // Given the expected section and index, the following code will
            // try to account for missing sections (no names starting with..)
            // It will compute the scroll space of surrounding empty sections
            // and interpolate the currently visible letter's range across the
            // available space, so that there is always some list movement while
            // the user moves the thumb.
            int nextIndex = count;
            int prevIndex = targetIndex;
            int prevSection = targetSection;
            int nextSection = targetSection + 1;

            // Assume the next section is unique
            if (targetSection < sectionCount - 1) {
                nextIndex = mSectionIndexer.getPositionForSection(targetSection + 1);
            }

            // Find the previous index if we're slicing the previous section
            if (nextIndex == targetIndex) {
                // Non-existent letter
                while (targetSection > 0) {
                    targetSection--;
                    prevIndex = mSectionIndexer.getPositionForSection(targetSection);
                    if (prevIndex != targetIndex) {
                        prevSection = targetSection;
                        sectionIndex = targetSection;
                        break;
                    } else if (targetSection == 0) {
                        // When section reaches 0 here, sectionIndex must follow it.
                        // Assuming mSectionIndexer.getPositionForSection(0) == 0.
                        sectionIndex = 0;
                        break;
                    }
                }
            }

            // Find the next index, in case the assumed next index is not
            // unique. For instance, if there is no P, then request for P's
            // position actually returns Q's. So we need to look ahead to make
            // sure that there is really a Q at Q's position. If not, move
            // further down...
            int nextNextSection = nextSection + 1;
            while (nextNextSection < sectionCount &&
                    mSectionIndexer.getPositionForSection(nextNextSection) == nextIndex) {
                nextNextSection++;
                nextSection++;
            }

            // Compute the beginning and ending scroll range percentage of the
            // currently visible section. This could be equal to or greater than
            // (1 / nSections). If the target position is near the previous
            // position, snap to the previous position.
            final float prevPosition = (float) prevSection / sectionCount;
            final float nextPosition = (float) nextSection / sectionCount;
            final float snapThreshold = (count == 0) ? Float.MAX_VALUE : .125f / count;
            if (prevSection == exactSection && position - prevPosition < snapThreshold) {
                targetIndex = prevIndex;
            } else {
                targetIndex = prevIndex + (int) ((nextIndex - prevIndex) * (position - prevPosition)
                    / (nextPosition - prevPosition));
            }

            // Clamp to valid positions.
            targetIndex = MathUtils.constrain(targetIndex, 0, count - 1);

            if (mList instanceof ExpandableListView) {
                final ExpandableListView expList = (ExpandableListView) mList;
                expList.setSelectionFromTop(expList.getFlatListPosition(
                        ExpandableListView.getPackedPositionForGroup(targetIndex + mHeaderCount)),
                        0);
            } else if (mList instanceof ListView) {
                ((ListView) mList).setSelectionFromTop(targetIndex + mHeaderCount, 0);
            } else {
                mList.setSelection(targetIndex + mHeaderCount);
            }
        } else {
            final int index = MathUtils.constrain((int) (position * count), 0, count - 1);

            if (mList instanceof ExpandableListView) {
                ExpandableListView expList = (ExpandableListView) mList;
                expList.setSelectionFromTop(expList.getFlatListPosition(
                        ExpandableListView.getPackedPositionForGroup(index + mHeaderCount)), 0);
            } else if (mList instanceof ListView) {
                ((ListView)mList).setSelectionFromTop(index + mHeaderCount, 0);
            } else {
                mList.setSelection(index + mHeaderCount);
            }

            sectionIndex = -1;
        }

        if (mCurrentSection != sectionIndex) {
            mCurrentSection = sectionIndex;

            final boolean hasPreview = transitionPreviewLayout(sectionIndex);
            if (!mShowingPreview && hasPreview) {
                transitionToDragging();
            } else if (mShowingPreview && !hasPreview) {
                transitionToVisible();
            }
        }
public voidsetAlwaysShow(boolean alwaysShow)

param
alwaysShow Whether the fast scroll thumb should always be shown

        if (mAlwaysShow != alwaysShow) {
            mAlwaysShow = alwaysShow;

            onStateDependencyChanged(false);
        }
public voidsetEnabled(boolean enabled)

param
enabled Whether the fast scroll thumb is enabled.

        if (mEnabled != enabled) {
            mEnabled = enabled;

            onStateDependencyChanged(true);
        }
public voidsetScrollBarStyle(int style)

        if (mScrollBarStyle != style) {
            mScrollBarStyle = style;

            updateLayout();
        }
public voidsetScrollbarPosition(int position)

        if (position == View.SCROLLBAR_POSITION_DEFAULT) {
            position = mList.isLayoutRtl() ?
                    View.SCROLLBAR_POSITION_LEFT : View.SCROLLBAR_POSITION_RIGHT;
        }

        if (mScrollbarPosition != position) {
            mScrollbarPosition = position;
            mLayoutFromRight = position != View.SCROLLBAR_POSITION_LEFT;

            final int previewResId = mPreviewResId[mLayoutFromRight ? PREVIEW_RIGHT : PREVIEW_LEFT];
            mPreviewImage.setBackgroundResource(previewResId);

            // Add extra padding for text.
            final Drawable background = mPreviewImage.getBackground();
            if (background != null) {
                final Rect padding = mTempBounds;
                background.getPadding(padding);
                padding.offset(mPreviewPadding, mPreviewPadding);
                mPreviewImage.setPadding(padding.left, padding.top, padding.right, padding.bottom);
            }

            // Requires re-layout.
            updateLayout();
        }
private voidsetState(int state)

        mList.removeCallbacks(mDeferHide);

        if (mAlwaysShow && state == STATE_NONE) {
            state = STATE_VISIBLE;
        }

        if (state == mState) {
            return;
        }

        switch (state) {
            case STATE_NONE:
                transitionToHidden();
                break;
            case STATE_VISIBLE:
                transitionToVisible();
                break;
            case STATE_DRAGGING:
                if (transitionPreviewLayout(mCurrentSection)) {
                    transitionToDragging();
                } else {
                    transitionToVisible();
                }
                break;
        }

        mState = state;

        refreshDrawablePressedState();
public voidsetStyle(int resId)

        final Context context = mList.getContext();
        final TypedArray ta = context.obtainStyledAttributes(null,
                com.android.internal.R.styleable.FastScroll, android.R.attr.fastScrollStyle, resId);
        final int N = ta.getIndexCount();
        for (int i = 0; i < N; i++) {
            final int index = ta.getIndex(i);
            switch (index) {
                case com.android.internal.R.styleable.FastScroll_position:
                    mOverlayPosition = ta.getInt(index, OVERLAY_FLOATING);
                    break;
                case com.android.internal.R.styleable.FastScroll_backgroundLeft:
                    mPreviewResId[PREVIEW_LEFT] = ta.getResourceId(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_backgroundRight:
                    mPreviewResId[PREVIEW_RIGHT] = ta.getResourceId(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_thumbDrawable:
                    mThumbDrawable = ta.getDrawable(index);
                    break;
                case com.android.internal.R.styleable.FastScroll_trackDrawable:
                    mTrackDrawable = ta.getDrawable(index);
                    break;
                case com.android.internal.R.styleable.FastScroll_textAppearance:
                    mTextAppearance = ta.getResourceId(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_textColor:
                    mTextColor = ta.getColorStateList(index);
                    break;
                case com.android.internal.R.styleable.FastScroll_textSize:
                    mTextSize = ta.getDimensionPixelSize(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_minWidth:
                    mPreviewMinWidth = ta.getDimensionPixelSize(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_minHeight:
                    mPreviewMinHeight = ta.getDimensionPixelSize(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_thumbMinWidth:
                    mThumbMinWidth = ta.getDimensionPixelSize(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_thumbMinHeight:
                    mThumbMinHeight = ta.getDimensionPixelSize(index, 0);
                    break;
                case com.android.internal.R.styleable.FastScroll_padding:
                    mPreviewPadding = ta.getDimensionPixelSize(index, 0);
                    break;
            }
        }

        updateAppearance();
private voidsetThumbPos(float position)
Positions the thumb and preview widgets.

param
position The position, between 0 and 1, along the track at which to place the thumb.

        final Rect container = mContainerRect;
        final int top = container.top;
        final int bottom = container.bottom;

        final View trackImage = mTrackImage;
        final View thumbImage = mThumbImage;
        final float min = trackImage.getTop();
        final float max = trackImage.getBottom();
        final float offset = min;
        final float range = max - min;
        final float thumbMiddle = position * range + offset;
        thumbImage.setTranslationY(thumbMiddle - thumbImage.getHeight() / 2);

        final View previewImage = mPreviewImage;
        final float previewHalfHeight = previewImage.getHeight() / 2f;
        final float previewPos;
        switch (mOverlayPosition) {
            case OVERLAY_AT_THUMB:
                previewPos = thumbMiddle;
                break;
            case OVERLAY_ABOVE_THUMB:
                previewPos = thumbMiddle - previewHalfHeight;
                break;
            case OVERLAY_FLOATING:
            default:
                previewPos = 0;
                break;
        }

        // Center the preview on the thumb, constrained to the list bounds.
        final float minP = top + previewHalfHeight;
        final float maxP = bottom - previewHalfHeight;
        final float previewMiddle = MathUtils.constrain(previewPos, minP, maxP);
        final float previewTop = previewMiddle - previewHalfHeight;
        previewImage.setTranslationY(previewTop);

        mPrimaryText.setTranslationY(previewTop);
        mSecondaryText.setTranslationY(previewTop);
private voidstartPendingDrag()
Delays dragging until after the framework has determined that the user is scrolling, rather than tapping.

        mPendingDrag = SystemClock.uptimeMillis() + TAP_TIMEOUT;
public voidstop()
Immediately transitions the fast scroller decorations to a hidden state.

        setState(STATE_NONE);
private booleantransitionPreviewLayout(int sectionIndex)
Transitions the preview text to a new section. Handles animation, measurement, and layout. If the new preview text is empty, returns false.

param
sectionIndex The section index to which the preview should transition.
return
False if the new preview text is empty.

        final Object[] sections = mSections;
        String text = null;
        if (sections != null && sectionIndex >= 0 && sectionIndex < sections.length) {
            final Object section = sections[sectionIndex];
            if (section != null) {
                text = section.toString();
            }
        }

        final Rect bounds = mTempBounds;
        final View preview = mPreviewImage;
        final TextView showing;
        final TextView target;
        if (mShowingPrimary) {
            showing = mPrimaryText;
            target = mSecondaryText;
        } else {
            showing = mSecondaryText;
            target = mPrimaryText;
        }

        // Set and layout target immediately.
        target.setText(text);
        measurePreview(target, bounds);
        applyLayout(target, bounds);

        if (mPreviewAnimation != null) {
            mPreviewAnimation.cancel();
        }

        // Cross-fade preview text.
        final Animator showTarget = animateAlpha(target, 1f).setDuration(DURATION_CROSS_FADE);
        final Animator hideShowing = animateAlpha(showing, 0f).setDuration(DURATION_CROSS_FADE);
        hideShowing.addListener(mSwitchPrimaryListener);

        // Apply preview image padding and animate bounds, if necessary.
        bounds.left -= preview.getPaddingLeft();
        bounds.top -= preview.getPaddingTop();
        bounds.right += preview.getPaddingRight();
        bounds.bottom += preview.getPaddingBottom();
        final Animator resizePreview = animateBounds(preview, bounds);
        resizePreview.setDuration(DURATION_RESIZE);

        mPreviewAnimation = new AnimatorSet();
        final AnimatorSet.Builder builder = mPreviewAnimation.play(hideShowing).with(showTarget);
        builder.with(resizePreview);

        // The current preview size is unaffected by hidden or showing. It's
        // used to set starting scales for things that need to be scaled down.
        final int previewWidth = preview.getWidth() - preview.getPaddingLeft()
                - preview.getPaddingRight();

        // If target is too large, shrink it immediately to fit and expand to
        // target size. Otherwise, start at target size.
        final int targetWidth = target.getWidth();
        if (targetWidth > previewWidth) {
            target.setScaleX((float) previewWidth / targetWidth);
            final Animator scaleAnim = animateScaleX(target, 1f).setDuration(DURATION_RESIZE);
            builder.with(scaleAnim);
        } else {
            target.setScaleX(1f);
        }

        // If showing is larger than target, shrink to target size.
        final int showingWidth = showing.getWidth();
        if (showingWidth > targetWidth) {
            final float scale = (float) targetWidth / showingWidth;
            final Animator scaleAnim = animateScaleX(showing, scale).setDuration(DURATION_RESIZE);
            builder.with(scaleAnim);
        }

        mPreviewAnimation.start();

        return !TextUtils.isEmpty(text);
private voidtransitionToDragging()
Shows the thumb, preview, and track.

        if (mDecorAnimation != null) {
            mDecorAnimation.cancel();
        }

        final Animator fadeIn = groupAnimatorOfFloat(
                View.ALPHA, 1f, mThumbImage, mTrackImage, mPreviewImage)
                .setDuration(DURATION_FADE_IN);
        final Animator slideIn = groupAnimatorOfFloat(
                View.TRANSLATION_X, 0f, mThumbImage, mTrackImage).setDuration(DURATION_FADE_IN);

        mDecorAnimation = new AnimatorSet();
        mDecorAnimation.playTogether(fadeIn, slideIn);
        mDecorAnimation.start();

        mShowingPreview = true;
private voidtransitionToHidden()
Shows nothing.

        if (mDecorAnimation != null) {
            mDecorAnimation.cancel();
        }

        final Animator fadeOut = groupAnimatorOfFloat(View.ALPHA, 0f, mThumbImage, mTrackImage,
                mPreviewImage, mPrimaryText, mSecondaryText).setDuration(DURATION_FADE_OUT);

        // Push the thumb and track outside the list bounds.
        final float offset = mLayoutFromRight ? mThumbImage.getWidth() : -mThumbImage.getWidth();
        final Animator slideOut = groupAnimatorOfFloat(
                View.TRANSLATION_X, offset, mThumbImage, mTrackImage)
                .setDuration(DURATION_FADE_OUT);

        mDecorAnimation = new AnimatorSet();
        mDecorAnimation.playTogether(fadeOut, slideOut);
        mDecorAnimation.start();

        mShowingPreview = false;
private voidtransitionToVisible()
Shows the thumb and track.

        if (mDecorAnimation != null) {
            mDecorAnimation.cancel();
        }

        final Animator fadeIn = groupAnimatorOfFloat(View.ALPHA, 1f, mThumbImage, mTrackImage)
                .setDuration(DURATION_FADE_IN);
        final Animator fadeOut = groupAnimatorOfFloat(
                View.ALPHA, 0f, mPreviewImage, mPrimaryText, mSecondaryText)
                .setDuration(DURATION_FADE_OUT);
        final Animator slideIn = groupAnimatorOfFloat(
                View.TRANSLATION_X, 0f, mThumbImage, mTrackImage).setDuration(DURATION_FADE_IN);

        mDecorAnimation = new AnimatorSet();
        mDecorAnimation.playTogether(fadeIn, fadeOut, slideIn);
        mDecorAnimation.start();

        mShowingPreview = false;
private voidupdateAppearance()

        final Context context = mList.getContext();
        int width = 0;

        // Add track to overlay if it has an image.
        mTrackImage.setImageDrawable(mTrackDrawable);
        if (mTrackDrawable != null) {
            width = Math.max(width, mTrackDrawable.getIntrinsicWidth());
        }

        // Add thumb to overlay if it has an image.
        mThumbImage.setImageDrawable(mThumbDrawable);
        mThumbImage.setMinimumWidth(mThumbMinWidth);
        mThumbImage.setMinimumHeight(mThumbMinHeight);
        if (mThumbDrawable != null) {
            width = Math.max(width, mThumbDrawable.getIntrinsicWidth());
        }

        // Account for minimum thumb width.
        mWidth = Math.max(width, mThumbMinWidth);

        mPreviewImage.setMinimumWidth(mPreviewMinWidth);
        mPreviewImage.setMinimumHeight(mPreviewMinHeight);

        if (mTextAppearance != 0) {
            mPrimaryText.setTextAppearance(context, mTextAppearance);
            mSecondaryText.setTextAppearance(context, mTextAppearance);
        }

        if (mTextColor != null) {
            mPrimaryText.setTextColor(mTextColor);
            mSecondaryText.setTextColor(mTextColor);
        }

        if (mTextSize > 0) {
            mPrimaryText.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
            mSecondaryText.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
        }

        final int textMinSize = Math.max(0, mPreviewMinHeight);
        mPrimaryText.setMinimumWidth(textMinSize);
        mPrimaryText.setMinimumHeight(textMinSize);
        mPrimaryText.setIncludeFontPadding(false);
        mSecondaryText.setMinimumWidth(textMinSize);
        mSecondaryText.setMinimumHeight(textMinSize);
        mSecondaryText.setIncludeFontPadding(false);

        refreshDrawablePressedState();
private voidupdateContainerRect()
Updates the container rectangle used for layout.

        final AbsListView list = mList;
        list.resolvePadding();

        final Rect container = mContainerRect;
        container.left = 0;
        container.top = 0;
        container.right = list.getWidth();
        container.bottom = list.getHeight();

        final int scrollbarStyle = mScrollBarStyle;
        if (scrollbarStyle == View.SCROLLBARS_INSIDE_INSET
                || scrollbarStyle == View.SCROLLBARS_INSIDE_OVERLAY) {
            container.left += list.getPaddingLeft();
            container.top += list.getPaddingTop();
            container.right -= list.getPaddingRight();
            container.bottom -= list.getPaddingBottom();

            // In inset mode, we need to adjust for padded scrollbar width.
            if (scrollbarStyle == View.SCROLLBARS_INSIDE_INSET) {
                final int width = getWidth();
                if (mScrollbarPosition == View.SCROLLBAR_POSITION_RIGHT) {
                    container.right += width;
                } else {
                    container.left -= width;
                }
            }
        }
public voidupdateLayout()
Measures and layouts the scrollbar and decorations.

        // Prevent re-entry when RTL properties change as a side-effect of
        // resolving padding.
        if (mUpdatingLayout) {
            return;
        }

        mUpdatingLayout = true;

        updateContainerRect();

        layoutThumb();
        layoutTrack();

        final Rect bounds = mTempBounds;
        measurePreview(mPrimaryText, bounds);
        applyLayout(mPrimaryText, bounds);
        measurePreview(mSecondaryText, bounds);
        applyLayout(mSecondaryText, bounds);

        if (mPreviewImage != null) {
            // Apply preview image padding.
            bounds.left -= mPreviewImage.getPaddingLeft();
            bounds.top -= mPreviewImage.getPaddingTop();
            bounds.right += mPreviewImage.getPaddingRight();
            bounds.bottom += mPreviewImage.getPaddingBottom();
            applyLayout(mPreviewImage, bounds);
        }

        mUpdatingLayout = false;
private voidupdateLongList(int childCount, int itemCount)

        final boolean longList = childCount > 0 && itemCount / childCount >= MIN_PAGES;
        if (mLongList != longList) {
            mLongList = longList;

            onStateDependencyChanged(false);
        }