launcher3/folder/Folder.java

/*
 * Copyright (C) 2008 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;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Point;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.Build;
import android.os.Bundle;
import android.text.InputType;
import android.text.Selection;
import android.text.Spannable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.ActionMode;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.AnimationUtils;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputMethodManager;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.android.launcher3.CellLayout.CellInfo;
import com.android.launcher3.DragController.DragListener;
import com.android.launcher3.FolderInfo.FolderListener;
import com.android.launcher3.UninstallDropTarget.UninstallSource;
import com.android.launcher3.Workspace.ItemOperator;
import com.android.launcher3.accessibility.LauncherAccessibilityDelegate.AccessibilityDragSource;
import com.android.launcher3.util.Thunk;
import com.android.launcher3.util.UiThreadCircularReveal;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

/**
 * Represents a set of icons chosen by the user or generated by the system.
 */
public class Folder extends LinearLayout implements DragSource, View.OnClickListener,
        View.OnLongClickListener, DropTarget, FolderListener, TextView.OnEditorActionListener,
        View.OnFocusChangeListener, DragListener, UninstallSource, AccessibilityDragSource,
        Stats.LaunchSourceProvider {
    private static final String TAG = "Launcher.Folder";

    /**
     * We avoid measuring {@link #mContentWrapper} with a 0 width or height, as this
     * results in CellLayout being measured as UNSPECIFIED, which it does not support.
     */
    private static final int MIN_CONTENT_DIMEN = 5;

    static final int STATE_NONE = -1;
    static final int STATE_SMALL = 0;
    static final int STATE_ANIMATING = 1;
    static final int STATE_OPEN = 2;

    /**
     * Time for which the scroll hint is shown before automatically changing page.
     */
    public static final int SCROLL_HINT_DURATION = DragController.SCROLL_DELAY;

    /**
     * Fraction of icon width which behave as scroll region.
     */
    private static final float ICON_OVERSCROLL_WIDTH_FACTOR = 0.45f;

    private static final int FOLDER_NAME_ANIMATION_DURATION = 633;

    private static final int REORDER_DELAY = 250;
    private static final int ON_EXIT_CLOSE_DELAY = 400;
    private static final Rect sTempRect = new Rect();

    private static String sDefaultFolderName;
    private static String sHintText;

    private final Alarm mReorderAlarm = new Alarm();
    private final Alarm mOnExitAlarm = new Alarm();
    private final Alarm mOnScrollHintAlarm = new Alarm();
    @Thunk final Alarm mScrollPauseAlarm = new Alarm();

    @Thunk final ArrayList<View> mItemsInReadingOrder = new ArrayList<View>();

    private final int mExpandDuration;
    private final int mMaterialExpandDuration;
    private final int mMaterialExpandStagger;

    private final InputMethodManager mInputMethodManager;

    protected final Launcher mLauncher;
    protected DragController mDragController;
    protected FolderInfo mInfo;

    @Thunk FolderIcon mFolderIcon;

    @Thunk FolderPagedView mContent;
    @Thunk View mContentWrapper;
    ExtendedEditText mFolderName;

    private View mFooter;
    private int mFooterHeight;

    // Cell ranks used for drag and drop
    @Thunk int mTargetRank, mPrevTargetRank, mEmptyCellRank;

    @Thunk int mState = STATE_NONE;
    private boolean mRearrangeOnClose = false;
    boolean mItemsInvalidated = false;
    private ShortcutInfo mCurrentDragInfo;
    private View mCurrentDragView;
    private boolean mIsExternalDrag;
    boolean mSuppressOnAdd = false;
    private boolean mDragInProgress = false;
    private boolean mDeleteFolderOnDropCompleted = false;
    private boolean mSuppressFolderDeletion = false;
    private boolean mItemAddedBackToSelfViaIcon = false;
    @Thunk float mFolderIconPivotX;
    @Thunk float mFolderIconPivotY;
    private boolean mIsEditingName = false;

    private boolean mDestroyed;

    @Thunk Runnable mDeferredAction;
    private boolean mDeferDropAfterUninstall;
    private boolean mUninstallSuccessful;

    // Folder scrolling
    private int mScrollAreaOffset;

    @Thunk int mScrollHintDir = DragController.SCROLL_NONE;
    @Thunk int mCurrentScrollDir = DragController.SCROLL_NONE;

    /**
     * Used to inflate the Workspace from XML.
     *
     * @param context The application's context.
     * @param attrs The attributes set containing the Workspace's customization values.
     */
    public Folder(Context context, AttributeSet attrs) {
        super(context, attrs);
        setAlwaysDrawnWithCacheEnabled(false);
        mInputMethodManager = (InputMethodManager)
                getContext().getSystemService(Context.INPUT_METHOD_SERVICE);

        Resources res = getResources();
        mExpandDuration = res.getInteger(R.integer.config_folderExpandDuration);
        mMaterialExpandDuration = res.getInteger(R.integer.config_materialFolderExpandDuration);
        mMaterialExpandStagger = res.getInteger(R.integer.config_materialFolderExpandStagger);

        if (sDefaultFolderName == null) {
            sDefaultFolderName = res.getString(R.string.folder_name);
        }
        if (sHintText == null) {
            sHintText = res.getString(R.string.folder_hint_text);
        }
        mLauncher = (Launcher) context;
        // We need this view to be focusable in touch mode so that when text editing of the folder
        // name is complete, we have something to focus on, thus hiding the cursor and giving
        // reliable behavior when clicking the text field (since it will always gain focus on click).
        setFocusableInTouchMode(true);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mContentWrapper = findViewById(R.id.folder_content_wrapper);
        mContent = (FolderPagedView) findViewById(R.id.folder_content);
        mContent.setFolder(this);

        mFolderName = (ExtendedEditText) findViewById(R.id.folder_name);
        mFolderName.setOnBackKeyListener(new ExtendedEditText.OnBackKeyListener() {
            @Override
            public boolean onBackKey() {
                // Close the activity on back key press
                doneEditingFolderName(true);
                return false;
            }
        });
        mFolderName.setOnFocusChangeListener(this);

        // We disable action mode for now since it messes up the view on phones
        mFolderName.setCustomSelectionActionModeCallback(mActionModeCallback);
        mFolderName.setOnEditorActionListener(this);
        mFolderName.setSelectAllOnFocus(true);
        mFolderName.setInputType(mFolderName.getInputType() |
                InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS | InputType.TYPE_TEXT_FLAG_CAP_WORDS);

        mFooter = findViewById(R.id.folder_footer);

        // We find out how tall footer wants to be (it is set to wrap_content), so that
        // we can allocate the appropriate amount of space for it.
        int measureSpec = MeasureSpec.UNSPECIFIED;
        mFooter.measure(measureSpec, measureSpec);
        mFooterHeight = mFooter.getMeasuredHeight();
    }

    private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {
        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
            return false;
        }

        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
            return false;
        }

        public void onDestroyActionMode(ActionMode mode) {
        }

        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
            return false;
        }
    };

    public void onClick(View v) {
        Object tag = v.getTag();
        if (tag instanceof ShortcutInfo) {
            mLauncher.onClick(v);
        }
    }

    public boolean onLongClick(View v) {
        // Return if global dragging is not enabled
        if (!mLauncher.isDraggingEnabled()) return true;
        return beginDrag(v, false);
    }

    private boolean beginDrag(View v, boolean accessible) {
        Object tag = v.getTag();
        if (tag instanceof ShortcutInfo) {
            ShortcutInfo item = (ShortcutInfo) tag;
            if (!v.isInTouchMode()) {
                return false;
            }

            mLauncher.getWorkspace().beginDragShared(v, new Point(), this, accessible);

            mCurrentDragInfo = item;
            mEmptyCellRank = item.rank;
            mCurrentDragView = v;

            mContent.removeItem(mCurrentDragView);
            mInfo.remove(mCurrentDragInfo);
            mDragInProgress = true;
            mItemAddedBackToSelfViaIcon = false;
        }
        return true;
    }

    @Override
    public void startDrag(CellInfo cellInfo, boolean accessible) {
        beginDrag(cellInfo.cell, accessible);
    }

    @Override
    public void enableAccessibleDrag(boolean enable) {
        mLauncher.getSearchDropTargetBar().enableAccessibleDrag(enable);
        for (int i = 0; i < mContent.getChildCount(); i++) {
            mContent.getPageAt(i).enableAccessibleDrag(enable, CellLayout.FOLDER_ACCESSIBILITY_DRAG);
        }

        mFooter.setImportantForAccessibility(enable ? IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS :
            IMPORTANT_FOR_ACCESSIBILITY_AUTO);
        mLauncher.getWorkspace().setAddNewPageOnDrag(!enable);
    }

    public boolean isEditingName() {
        return mIsEditingName;
    }

    public void startEditingFolderName() {
        mFolderName.setHint("");
        mIsEditingName = true;
    }

    public void dismissEditingName() {
        mInputMethodManager.hideSoftInputFromWindow(getWindowToken(), 0);
        doneEditingFolderName(true);
    }

    public void doneEditingFolderName(boolean commit) {
        mFolderName.setHint(sHintText);
        // Convert to a string here to ensure that no other state associated with the text field
        // gets saved.
        String newTitle = mFolderName.getText().toString();
        mInfo.setTitle(newTitle);
        LauncherModel.updateItemInDatabase(mLauncher, mInfo);

        if (commit) {
            sendCustomAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED,
                    String.format(getContext().getString(R.string.folder_renamed), newTitle));
        }

        // This ensures that focus is gained every time the field is clicked, which selects all
        // the text and brings up the soft keyboard if necessary.
        mFolderName.clearFocus();

        Selection.setSelection((Spannable) mFolderName.getText(), 0, 0);
        mIsEditingName = false;
    }

    public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
        if (actionId == EditorInfo.IME_ACTION_DONE) {
            dismissEditingName();
            return true;
        }
        return false;
    }

    public View getEditTextRegion() {
        return mFolderName;
    }

    /**
     * We need to handle touch events to prevent them from falling through to the workspace below.
     */
    @SuppressLint("ClickableViewAccessibility")
    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        return true;
    }

    public void setDragController(DragController dragController) {
        mDragController = dragController;
    }

    public void setFolderIcon(FolderIcon icon) {
        mFolderIcon = icon;
    }

    @Override
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        // When the folder gets focus, we don't want to announce the list of items.
        return true;
    }

    /**
     * @return the FolderInfo object associated with this folder
     */
    public FolderInfo getInfo() {
        return mInfo;
    }

    void bind(FolderInfo info) {
        mInfo = info;
        ArrayList<ShortcutInfo> children = info.contents;
        Collections.sort(children, ITEM_POS_COMPARATOR);

        ArrayList<ShortcutInfo> overflow = mContent.bindItems(children);

        // If our folder has too many items we prune them from the list. This is an issue
        // when upgrading from the old Folders implementation which could contain an unlimited
        // number of items.
        for (ShortcutInfo item: overflow) {
            mInfo.remove(item);
            LauncherModel.deleteItemFromDatabase(mLauncher, item);
        }

        DragLayer.LayoutParams lp = (DragLayer.LayoutParams) getLayoutParams();
        if (lp == null) {
            lp = new DragLayer.LayoutParams(0, 0);
            lp.customPosition = true;
            setLayoutParams(lp);
        }
        centerAboutIcon();

        mItemsInvalidated = true;
        updateTextViewFocus();
        mInfo.addListener(this);

        if (!sDefaultFolderName.contentEquals(mInfo.title)) {
            mFolderName.setText(mInfo.title);
        } else {
            mFolderName.setText("");
        }

        // In case any children didn't come across during loading, clean up the folder accordingly
        mFolderIcon.post(new Runnable() {
            public void run() {
                if (getItemCount() <= 1) {
                    replaceFolderWithFinalItem();
                }
            }
        });
    }

    /**
     * Creates a new UserFolder, inflated from R.layout.user_folder.
     *
     * @param launcher The main activity.
     *
     * @return A new UserFolder.
     */
    @SuppressLint("InflateParams")
    static Folder fromXml(Launcher launcher) {
        return (Folder) launcher.getLayoutInflater().inflate(R.layout.user_folder, null);
    }

    /**
     * This method is intended to make the UserFolder to be visually identical in size and position
     * to its associated FolderIcon. This allows for a seamless transition into the expanded state.
     */
    private void positionAndSizeAsIcon() {
        if (!(getParent() instanceof DragLayer)) return;
        setScaleX(0.8f);
        setScaleY(0.8f);
        setAlpha(0f);
        mState = STATE_SMALL;
    }

    private void prepareReveal() {
        setScaleX(1f);
        setScaleY(1f);
        setAlpha(1f);
        mState = STATE_SMALL;
    }

    public void animateOpen() {
        if (!(getParent() instanceof DragLayer)) return;

        mContent.completePendingPageChanges();
        if (!mDragInProgress) {
            // Open on the first page.
            mContent.snapToPageImmediately(0);
        }

        // This is set to true in close(), but isn't reset to false until onDropCompleted(). This
        // leads to an consistent state if you drag out of the folder and drag back in without
        // dropping. One resulting issue is that replaceFolderWithFinalItem() can be called twice.
        mDeleteFolderOnDropCompleted = false;

        Animator openFolderAnim = null;
        final Runnable onCompleteRunnable;
        if (!Utilities.ATLEAST_LOLLIPOP) {
            positionAndSizeAsIcon();
            centerAboutIcon();

            PropertyValuesHolder alpha = PropertyValuesHolder.ofFloat("alpha", 1);
            PropertyValuesHolder scaleX = PropertyValuesHolder.ofFloat("scaleX", 1.0f);
            PropertyValuesHolder scaleY = PropertyValuesHolder.ofFloat("scaleY", 1.0f);
            final ObjectAnimator oa =
                LauncherAnimUtils.ofPropertyValuesHolder(this, alpha, scaleX, scaleY);
            oa.setDuration(mExpandDuration);
            openFolderAnim = oa;

            setLayerType(LAYER_TYPE_HARDWARE, null);
            onCompleteRunnable = new Runnable() {
                @Override
                public void run() {
                    setLayerType(LAYER_TYPE_NONE, null);
                }
            };
        } else {
            prepareReveal();
            centerAboutIcon();

            AnimatorSet anim = LauncherAnimUtils.createAnimatorSet();
            int width = getPaddingLeft() + getPaddingRight() + mContent.getDesiredWidth();
            int height = getFolderHeight();

            float transX = - 0.075f * (width / 2 - getPivotX());
            float transY = - 0.075f * (height / 2 - getPivotY());
            setTranslationX(transX);
            setTranslationY(transY);
            PropertyValuesHolder tx = PropertyValuesHolder.ofFloat("translationX", transX, 0);
            PropertyValuesHolder ty = PropertyValuesHolder.ofFloat("translationY", transY, 0);

            Animator drift = ObjectAnimator.ofPropertyValuesHolder(this, tx, ty);
            drift.setDuration(mMaterialExpandDuration);
            drift.setStartDelay(mMaterialExpandStagger);
            drift.setInterpolator(new LogDecelerateInterpolator(100, 0));

            int rx = (int) Math.max(Math.max(width - getPivotX(), 0), getPivotX());
            int ry = (int) Math.max(Math.max(height - getPivotY(), 0), getPivotY());
            float radius = (float) Math.hypot(rx, ry);

            Animator reveal = UiThreadCircularReveal.createCircularReveal(this, (int) getPivotX(),
                    (int) getPivotY(), 0, radius);
            reveal.setDuration(mMaterialExpandDuration);
            reveal.setInterpolator(new LogDecelerateInterpolator(100, 0));

            mContentWrapper.setAlpha(0f);
            Animator iconsAlpha = ObjectAnimator.ofFloat(mContentWrapper, "alpha", 0f, 1f);
            iconsAlpha.setDuration(mMaterialExpandDuration);
            iconsAlpha.setStartDelay(mMaterialExpandStagger);
            iconsAlpha.setInterpolator(new AccelerateInterpolator(1.5f));

            mFooter.setAlpha(0f);
            Animator textAlpha = ObjectAnimator.ofFloat(mFooter, "alpha", 0f, 1f);
            textAlpha.setDuration(mMaterialExpandDuration);
            textAlpha.setStartDelay(mMaterialExpandStagger);
            textAlpha.setInterpolator(new AccelerateInterpolator(1.5f));

            anim.play(drift);
            anim.play(iconsAlpha);
            anim.play(textAlpha);
            anim.play(reveal);

            openFolderAnim = anim;

            mContentWrapper.setLayerType(LAYER_TYPE_HARDWARE, null);
            mFooter.setLayerType(LAYER_TYPE_HARDWARE, null);
            onCompleteRunnable = new Runnable() {
                @Override
                public void run() {
                    mContentWrapper.setLayerType(LAYER_TYPE_NONE, null);
                    mContentWrapper.setLayerType(LAYER_TYPE_NONE, null);
                }
            };
        }
        openFolderAnim.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationStart(Animator animation) {
                sendCustomAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED,
                        mContent.getAccessibilityDescription());
                mState = STATE_ANIMATING;
            }
            @Override
            public void onAnimationEnd(Animator animation) {
                mState = STATE_OPEN;

                onCompleteRunnable.run();
                mContent.setFocusOnFirstChild();
            }
        });

        // Footer animation
        if (mContent.getPageCount() > 1 && !mInfo.hasOption(FolderInfo.FLAG_MULTI_PAGE_ANIMATION)) {
            int footerWidth = mContent.getDesiredWidth()
                    - mFooter.getPaddingLeft() - mFooter.getPaddingRight();

            float textWidth =  mFolderName.getPaint().measureText(mFolderName.getText().toString());
            float translation = (footerWidth - textWidth) / 2;
            mFolderName.setTranslationX(mContent.mIsRtl ? -translation : translation);
            mContent.setMarkerScale(0);

            // Do not update the flag if we are in drag mode. The flag will be updated, when we
            // actually drop the icon.
            final boolean updateAnimationFlag = !mDragInProgress;
            openFolderAnim.addListener(new AnimatorListenerAdapter() {

                @Override
                public void onAnimationEnd(Animator animation) {
                    mFolderName.animate().setDuration(FOLDER_NAME_ANIMATION_DURATION)
                        .translationX(0)
                        .setInterpolator(Utilities.ATLEAST_LOLLIPOP ?
                                AnimationUtils.loadInterpolator(mLauncher,
                                        android.R.interpolator.fast_out_slow_in)
                                : new LogDecelerateInterpolator(100, 0));
                    mContent.animateMarkers();

                    if (updateAnimationFlag) {
                        mInfo.setOption(FolderInfo.FLAG_MULTI_PAGE_ANIMATION, true, mLauncher);
                    }
                }
            });
        } else {
            mFolderName.setTranslationX(0);
            mContent.setMarkerScale(1);
        }

        openFolderAnim.start();

        // Make sure the folder picks up the last drag move even if the finger doesn't move.
        if (mDragController.isDragging()) {
            mDragController.forceTouchMove();
        }

        FolderPagedView pages = (FolderPagedView) mContent;
        pages.verifyVisibleHighResIcons(pages.getNextPage());
    }

    public void beginExternalDrag(ShortcutInfo item) {
        mCurrentDragInfo = item;
        mEmptyCellRank = mContent.allocateRankForNewItem(item);
        mIsExternalDrag = true;
        mDragInProgress = true;

        // Since this folder opened by another controller, it might not get onDrop or
        // onDropComplete. Perform cleanup once drag-n-drop ends.
        mDragController.addDragListener(this);
    }

    @Override
    public void onDragStart(DragSource source, Object info, int dragAction) { }

    @Override
    public void onDragEnd() {
        if (mIsExternalDrag && mDragInProgress) {
            completeDragExit();
        }
        mDragController.removeDragListener(this);
    }

    @Thunk void sendCustomAccessibilityEvent(int type, String text) {
        AccessibilityManager accessibilityManager = (AccessibilityManager)
                getContext().getSystemService(Context.ACCESSIBILITY_SERVICE);
        if (accessibilityManager.isEnabled()) {
            AccessibilityEvent event = AccessibilityEvent.obtain(type);
            onInitializeAccessibilityEvent(event);
            event.getText().add(text);
            accessibilityManager.sendAccessibilityEvent(event);
        }
    }

    public void animateClosed() {
        if (!(getParent() instanceof DragLayer)) return;
        PropertyValuesHolder alpha = PropertyValuesHolder.ofFloat("alpha", 0);
        PropertyValuesHolder scaleX = PropertyValuesHolder.ofFloat("scaleX", 0.9f);
        PropertyValuesHolder scaleY = PropertyValuesHolder.ofFloat("scaleY", 0.9f);
        final ObjectAnimator oa =
                LauncherAnimUtils.ofPropertyValuesHolder(this, alpha, scaleX, scaleY);

        oa.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                setLayerType(LAYER_TYPE_NONE, null);
                close(true);
            }
            @Override
            public void onAnimationStart(Animator animation) {
                sendCustomAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED,
                        getContext().getString(R.string.folder_closed));
                mState = STATE_ANIMATING;
            }
        });
        oa.setDuration(mExpandDuration);
        setLayerType(LAYER_TYPE_HARDWARE, null);
        oa.start();
    }

    public void close(boolean wasAnimated) {
        // TODO: Clear all active animations.
        DragLayer parent = (DragLayer) getParent();
        if (parent != null) {
            parent.removeView(this);
        }
        mDragController.removeDropTarget(this);
        clearFocus();
        if (wasAnimated) {
            mFolderIcon.requestFocus();
        }

        if (mRearrangeOnClose) {
            rearrangeChildren();
            mRearrangeOnClose = false;
        }
        if (getItemCount() <= 1) {
            if (!mDragInProgress && !mSuppressFolderDeletion) {
                replaceFolderWithFinalItem();
            } else if (mDragInProgress) {
                mDeleteFolderOnDropCompleted = true;
            }
        }
        mSuppressFolderDeletion = false;
        clearDragInfo();
        mState = STATE_SMALL;
    }

    public boolean acceptDrop(DragObject d) {
        final ItemInfo item = (ItemInfo) d.dragInfo;
        final int itemType = item.itemType;
        return ((itemType == LauncherSettings.Favorites.ITEM_TYPE_APPLICATION ||
                    itemType == LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT) &&
                    !isFull());
    }

    public void onDragEnter(DragObject d) {
        mPrevTargetRank = -1;
        mOnExitAlarm.cancelAlarm();
        // Get the area offset such that the folder only closes if half the drag icon width
        // is outside the folder area
        mScrollAreaOffset = d.dragView.getDragRegionWidth() / 2 - d.xOffset;
    }

    OnAlarmListener mReorderAlarmListener = new OnAlarmListener() {
        public void onAlarm(Alarm alarm) {
            mContent.realTimeReorder(mEmptyCellRank, mTargetRank);
            mEmptyCellRank = mTargetRank;
        }
    };

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
    public boolean isLayoutRtl() {
        return (getLayoutDirection() == LAYOUT_DIRECTION_RTL);
    }

    @Override
    public void onDragOver(DragObject d) {
        onDragOver(d, REORDER_DELAY);
    }

    private int getTargetRank(DragObject d, float[] recycle) {
        recycle = d.getVisualCenter(recycle);
        return mContent.findNearestArea(
                (int) recycle[0] - getPaddingLeft(), (int) recycle[1] - getPaddingTop());
    }

    @Thunk void onDragOver(DragObject d, int reorderDelay) {
        if (mScrollPauseAlarm.alarmPending()) {
            return;
        }
        final float[] r = new float[2];
        mTargetRank = getTargetRank(d, r);

        if (mTargetRank != mPrevTargetRank) {
            mReorderAlarm.cancelAlarm();
            mReorderAlarm.setOnAlarmListener(mReorderAlarmListener);
            mReorderAlarm.setAlarm(REORDER_DELAY);
            mPrevTargetRank = mTargetRank;

            if (d.stateAnnouncer != null) {
                d.stateAnnouncer.announce(getContext().getString(R.string.move_to_position,
                        mTargetRank + 1));
            }
        }

        float x = r[0];
        int currentPage = mContent.getNextPage();

        float cellOverlap = mContent.getCurrentCellLayout().getCellWidth()
                * ICON_OVERSCROLL_WIDTH_FACTOR;
        boolean isOutsideLeftEdge = x < cellOverlap;
        boolean isOutsideRightEdge = x > (getWidth() - cellOverlap);

        if (currentPage > 0 && (mContent.mIsRtl ? isOutsideRightEdge : isOutsideLeftEdge)) {
            showScrollHint(DragController.SCROLL_LEFT, d);
        } else if (currentPage < (mContent.getPageCount() - 1)
                && (mContent.mIsRtl ? isOutsideLeftEdge : isOutsideRightEdge)) {
            showScrollHint(DragController.SCROLL_RIGHT, d);
        } else {
            mOnScrollHintAlarm.cancelAlarm();
            if (mScrollHintDir != DragController.SCROLL_NONE) {
                mContent.clearScrollHint();
                mScrollHintDir = DragController.SCROLL_NONE;
            }
        }
    }

    private void showScrollHint(int direction, DragObject d) {
        // Show scroll hint on the right
        if (mScrollHintDir != direction) {
            mContent.showScrollHint(direction);
            mScrollHintDir = direction;
        }

        // Set alarm for when the hint is complete
        if (!mOnScrollHintAlarm.alarmPending() || mCurrentScrollDir != direction) {
            mCurrentScrollDir = direction;
            mOnScrollHintAlarm.cancelAlarm();
            mOnScrollHintAlarm.setOnAlarmListener(new OnScrollHintListener(d));
            mOnScrollHintAlarm.setAlarm(SCROLL_HINT_DURATION);

            mReorderAlarm.cancelAlarm();
            mTargetRank = mEmptyCellRank;
        }
    }

    OnAlarmListener mOnExitAlarmListener = new OnAlarmListener() {
        public void onAlarm(Alarm alarm) {
            completeDragExit();
        }
    };

    public void completeDragExit() {
        if (mInfo.opened) {
            mLauncher.closeFolder();
            mRearrangeOnClose = true;
        } else if (mState == STATE_ANIMATING) {
            mRearrangeOnClose = true;
        } else {
            rearrangeChildren();
            clearDragInfo();
        }
    }

    private void clearDragInfo() {
        mCurrentDragInfo = null;
        mCurrentDragView = null;
        mSuppressOnAdd = false;
        mIsExternalDrag = false;
    }

    public void onDragExit(DragObject d) {
        // We only close the folder if this is a true drag exit, ie. not because
        // a drop has occurred above the folder.
        if (!d.dragComplete) {
            mOnExitAlarm.setOnAlarmListener(mOnExitAlarmListener);
            mOnExitAlarm.setAlarm(ON_EXIT_CLOSE_DELAY);
        }
        mReorderAlarm.cancelAlarm();

        mOnScrollHintAlarm.cancelAlarm();
        mScrollPauseAlarm.cancelAlarm();
        if (mScrollHintDir != DragController.SCROLL_NONE) {
            mContent.clearScrollHint();
            mScrollHintDir = DragController.SCROLL_NONE;
        }
    }

    /**
     * When performing an accessibility drop, onDrop is sent immediately after onDragEnter. So we
     * need to complete all transient states based on timers.
     */
    @Override
    public void prepareAccessibilityDrop() {
        if (mReorderAlarm.alarmPending()) {
            mReorderAlarm.cancelAlarm();
            mReorderAlarmListener.onAlarm(mReorderAlarm);
        }
    }

    public void onDropCompleted(final View target, final DragObject d,
            final boolean isFlingToDelete, final boolean success) {
        if (mDeferDropAfterUninstall) {
            Log.d(TAG, "Deferred handling drop because waiting for uninstall.");
            mDeferredAction = new Runnable() {
                    public void run() {
                        onDropCompleted(target, d, isFlingToDelete, success);
                        mDeferredAction = null;
                    }
                };
            return;
        }

        boolean beingCalledAfterUninstall = mDeferredAction != null;
        boolean successfulDrop =
                success && (!beingCalledAfterUninstall || mUninstallSuccessful);

        if (successfulDrop) {
            if (mDeleteFolderOnDropCompleted && !mItemAddedBackToSelfViaIcon && target != this) {
                replaceFolderWithFinalItem();
            }
        } else {
            // The drag failed, we need to return the item to the folder
            ShortcutInfo info = (ShortcutInfo) d.dragInfo;
            View icon = (mCurrentDragView != null && mCurrentDragView.getTag() == info)
                    ? mCurrentDragView : mContent.createNewView(info);
            ArrayList<View> views = getItemsInReadingOrder();
            views.add(info.rank, icon);
            mContent.arrangeChildren(views, views.size());
            mItemsInvalidated = true;

            mSuppressOnAdd = true;
            mFolderIcon.onDrop(d);
            mSuppressOnAdd = false;
        }

        if (target != this) {
            if (mOnExitAlarm.alarmPending()) {
                mOnExitAlarm.cancelAlarm();
                if (!successfulDrop) {
                    mSuppressFolderDeletion = true;
                }
                mScrollPauseAlarm.cancelAlarm();
                completeDragExit();
            }
        }

        mDeleteFolderOnDropCompleted = false;
        mDragInProgress = false;
        mItemAddedBackToSelfViaIcon = false;
        mCurrentDragInfo = null;
        mCurrentDragView = null;
        mSuppressOnAdd = false;

        // Reordering may have occured, and we need to save the new item locations. We do this once
        // at the end to prevent unnecessary database operations.
        updateItemLocationsInDatabaseBatch();

        // Use the item count to check for multi-page as the folder UI may not have
        // been refreshed yet.
        if (getItemCount() <= mContent.itemsPerPage()) {
            // Show the animation, next time something is added to the folder.
            mInfo.setOption(FolderInfo.FLAG_MULTI_PAGE_ANIMATION, false, mLauncher);
        }
    }

    @Override
    public void deferCompleteDropAfterUninstallActivity() {
        mDeferDropAfterUninstall = true;
    }

    @Override
    public void onUninstallActivityReturned(boolean success) {
        mDeferDropAfterUninstall = false;
        mUninstallSuccessful = success;
        if (mDeferredAction != null) {
            mDeferredAction.run();
        }
    }

    @Override
    public float getIntrinsicIconScaleFactor() {
        return 1f;
    }

    @Override
    public boolean supportsFlingToDelete() {
        return true;
    }

    @Override
    public boolean supportsAppInfoDropTarget() {
        return false;
    }

    @Override
    public boolean supportsDeleteDropTarget() {
        return true;
    }

    @Override
    public void onFlingToDelete(DragObject d, PointF vec) {
        // Do nothing
    }

    @Override
    public void onFlingToDeleteCompleted() {
        // Do nothing
    }

    private void updateItemLocationsInDatabaseBatch() {
        ArrayList<View> list = getItemsInReadingOrder();
        ArrayList<ItemInfo> items = new ArrayList<ItemInfo>();
        for (int i = 0; i < list.size(); i++) {
            View v = list.get(i);
            ItemInfo info = (ItemInfo) v.getTag();
            info.rank = i;
            items.add(info);
        }

        LauncherModel.moveItemsInDatabase(mLauncher, items, mInfo.id, 0);
    }

    public void addItemLocationsInDatabase() {
        ArrayList<View> list = getItemsInReadingOrder();
        for (int i = 0; i < list.size(); i++) {
            View v = list.get(i);
            ItemInfo info = (ItemInfo) v.getTag();
            LauncherModel.addItemToDatabase(mLauncher, info, mInfo.id, 0,
                    info.cellX, info.cellY);
        }
    }

    public void notifyDrop() {
        if (mDragInProgress) {
            mItemAddedBackToSelfViaIcon = true;
        }
    }

    public boolean isDropEnabled() {
        return true;
    }

    public boolean isFull() {
        return mContent.isFull();
    }

    private void centerAboutIcon() {
        DragLayer.LayoutParams lp = (DragLayer.LayoutParams) getLayoutParams();

        DragLayer parent = (DragLayer) mLauncher.findViewById(R.id.drag_layer);
        int width = getPaddingLeft() + getPaddingRight() + mContent.getDesiredWidth();
        int height = getFolderHeight();

        float scale = parent.getDescendantRectRelativeToSelf(mFolderIcon, sTempRect);

        DeviceProfile grid = mLauncher.getDeviceProfile();

        int centerX = (int) (sTempRect.left + sTempRect.width() * scale / 2);
        int centerY = (int) (sTempRect.top + sTempRect.height() * scale / 2);
        int centeredLeft = centerX - width / 2;
        int centeredTop = centerY - height / 2;

        // We need to bound the folder to the currently visible workspace area
        mLauncher.getWorkspace().getPageAreaRelativeToDragLayer(sTempRect);
        int left = Math.min(Math.max(sTempRect.left, centeredLeft),
                sTempRect.left + sTempRect.width() - width);
        int top = Math.min(Math.max(sTempRect.top, centeredTop),
                sTempRect.top + sTempRect.height() - height);
        if (grid.isPhone && (grid.availableWidthPx - width) < grid.iconSizePx) {
            // Center the folder if it is full (on phones only)
            left = (grid.availableWidthPx - width) / 2;
        } else if (width >= sTempRect.width()) {
            // If the folder doesn't fit within the bounds, center it about the desired bounds
            left = sTempRect.left + (sTempRect.width() - width) / 2;
        }
        if (height >= sTempRect.height()) {
            top = sTempRect.top + (sTempRect.height() - height) / 2;
        }

        int folderPivotX = width / 2 + (centeredLeft - left);
        int folderPivotY = height / 2 + (centeredTop - top);
        setPivotX(folderPivotX);
        setPivotY(folderPivotY);
        mFolderIconPivotX = (int) (mFolderIcon.getMeasuredWidth() *
                (1.0f * folderPivotX / width));
        mFolderIconPivotY = (int) (mFolderIcon.getMeasuredHeight() *
                (1.0f * folderPivotY / height));

        lp.width = width;
        lp.height = height;
        lp.x = left;
        lp.y = top;
    }

    float getPivotXForIconAnimation() {
        return mFolderIconPivotX;
    }
    float getPivotYForIconAnimation() {
        return mFolderIconPivotY;
    }

    private int getContentAreaHeight() {
        DeviceProfile grid = mLauncher.getDeviceProfile();
        Rect workspacePadding = grid.getWorkspacePadding(mContent.mIsRtl);
        int maxContentAreaHeight = grid.availableHeightPx -
                workspacePadding.top - workspacePadding.bottom -
                mFooterHeight;
        int height = Math.min(maxContentAreaHeight,
                mContent.getDesiredHeight());
        return Math.max(height, MIN_CONTENT_DIMEN);
    }

    private int getContentAreaWidth() {
        return Math.max(mContent.getDesiredWidth(), MIN_CONTENT_DIMEN);
    }

    private int getFolderHeight() {
        return getFolderHeight(getContentAreaHeight());
    }

    private int getFolderHeight(int contentAreaHeight) {
        return getPaddingTop() + getPaddingBottom() + contentAreaHeight + mFooterHeight;
    }

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int contentWidth = getContentAreaWidth();
        int contentHeight = getContentAreaHeight();

        int contentAreaWidthSpec = MeasureSpec.makeMeasureSpec(contentWidth, MeasureSpec.EXACTLY);
        int contentAreaHeightSpec = MeasureSpec.makeMeasureSpec(contentHeight, MeasureSpec.EXACTLY);

        mContent.setFixedSize(contentWidth, contentHeight);
        mContentWrapper.measure(contentAreaWidthSpec, contentAreaHeightSpec);

        if (mContent.getChildCount() > 0) {
            int cellIconGap = (mContent.getPageAt(0).getCellWidth()
                    - mLauncher.getDeviceProfile().iconSizePx) / 2;
            mFooter.setPadding(mContent.getPaddingLeft() + cellIconGap,
                    mFooter.getPaddingTop(),
                    mContent.getPaddingRight() + cellIconGap,
                    mFooter.getPaddingBottom());
        }
        mFooter.measure(contentAreaWidthSpec,
                MeasureSpec.makeMeasureSpec(mFooterHeight, MeasureSpec.EXACTLY));

        int folderWidth = getPaddingLeft() + getPaddingRight() + contentWidth;
        int folderHeight = getFolderHeight(contentHeight);
        setMeasuredDimension(folderWidth, folderHeight);
    }

    /**
     * Rearranges the children based on their rank.
     */
    public void rearrangeChildren() {
        rearrangeChildren(-1);
    }

    /**
     * Rearranges the children based on their rank.
     * @param itemCount if greater than the total children count, empty spaces are left at the end,
     * otherwise it is ignored.
     */
    public void rearrangeChildren(int itemCount) {
        ArrayList<View> views = getItemsInReadingOrder();
        mContent.arrangeChildren(views, Math.max(itemCount, views.size()));
        mItemsInvalidated = true;
    }

    // TODO remove this once GSA code fix is submitted
    public ViewGroup getContent() {
        return (ViewGroup) mContent;
    }

    public int getItemCount() {
        return mContent.getItemCount();
    }

    @Thunk void replaceFolderWithFinalItem() {
        // Add the last remaining child to the workspace in place of the folder
        Runnable onCompleteRunnable = new Runnable() {
            @Override
            public void run() {
                int itemCount = mInfo.contents.size();
                if (itemCount <= 1) {
                    View newIcon = null;

                    if (itemCount == 1) {
                        // Move the item from the folder to the workspace, in the position of the
                        // folder
                        CellLayout cellLayout = mLauncher.getCellLayout(mInfo.container,
                                mInfo.screenId);
                        ShortcutInfo finalItem = mInfo.contents.remove(0);
                        newIcon = mLauncher.createShortcut(cellLayout, finalItem);
                        LauncherModel.addOrMoveItemInDatabase(mLauncher, finalItem, mInfo.container,
                                mInfo.screenId, mInfo.cellX, mInfo.cellY);
                    }

                    // Remove the folder
                    mLauncher.removeItem(mFolderIcon, mInfo, true /* deleteFromDb */);
                    if (mFolderIcon instanceof DropTarget) {
                        mDragController.removeDropTarget((DropTarget) mFolderIcon);
                    }

                    if (newIcon != null) {
                        // We add the child after removing the folder to prevent both from existing
                        // at the same time in the CellLayout.  We need to add the new item with
                        // addInScreenFromBind() to ensure that hotseat items are placed correctly.
                        mLauncher.getWorkspace().addInScreenFromBind(newIcon, mInfo.container,
                                mInfo.screenId, mInfo.cellX, mInfo.cellY, mInfo.spanX, mInfo.spanY);

                        // Focus the newly created child
                        newIcon.requestFocus();
                    }
                }
            }
        };
        View finalChild = mContent.getLastItem();
        if (finalChild != null) {
            mFolderIcon.performDestroyAnimation(finalChild, onCompleteRunnable);
        } else {
            onCompleteRunnable.run();
        }
        mDestroyed = true;
    }

    boolean isDestroyed() {
        return mDestroyed;
    }

    // This method keeps track of the first and last item in the folder for the purposes
    // of keyboard focus
    public void updateTextViewFocus() {
        final View firstChild = mContent.getFirstItem();
        final View lastChild = mContent.getLastItem();
        if (firstChild != null && lastChild != null) {
            mFolderName.setNextFocusDownId(lastChild.getId());
            mFolderName.setNextFocusRightId(lastChild.getId());
            mFolderName.setNextFocusLeftId(lastChild.getId());
            mFolderName.setNextFocusUpId(lastChild.getId());
            // Hitting TAB from the folder name wraps around to the first item on the current
            // folder page, and hitting SHIFT+TAB from that item wraps back to the folder name.
            mFolderName.setNextFocusForwardId(firstChild.getId());
            // When clicking off the folder when editing the name, this Folder gains focus. When
            // pressing an arrow key from that state, give the focus to the first item.
            this.setNextFocusDownId(firstChild.getId());
            this.setNextFocusRightId(firstChild.getId());
            this.setNextFocusLeftId(firstChild.getId());
            this.setNextFocusUpId(firstChild.getId());
            // When pressing shift+tab in the above state, give the focus to the last item.
            setOnKeyListener(new OnKeyListener() {
                @Override
                public boolean onKey(View v, int keyCode, KeyEvent event) {
                    boolean isShiftPlusTab = keyCode == KeyEvent.KEYCODE_TAB &&
                            event.hasModifiers(KeyEvent.META_SHIFT_ON);
                    if (isShiftPlusTab && Folder.this.isFocused()) {
                        return lastChild.requestFocus();
                    }
                    return false;
                }
            });
        }
    }

    public void onDrop(DragObject d) {
        Runnable cleanUpRunnable = null;

        // If we are coming from All Apps space, we defer removing the extra empty screen
        // until the folder closes
        if (d.dragSource != mLauncher.getWorkspace() && !(d.dragSource instanceof Folder)) {
            cleanUpRunnable = new Runnable() {
                @Override
                public void run() {
                    mLauncher.exitSpringLoadedDragModeDelayed(true,
                            Launcher.EXIT_SPRINGLOADED_MODE_SHORT_TIMEOUT,
                            null);
                }
            };
        }

        // If the icon was dropped while the page was being scrolled, we need to compute
        // the target location again such that the icon is placed of the final page.
        if (!mContent.rankOnCurrentPage(mEmptyCellRank)) {
            // Reorder again.
            mTargetRank = getTargetRank(d, null);

            // Rearrange items immediately.
            mReorderAlarmListener.onAlarm(mReorderAlarm);

            mOnScrollHintAlarm.cancelAlarm();
            mScrollPauseAlarm.cancelAlarm();
        }
        mContent.completePendingPageChanges();

        View currentDragView;
        ShortcutInfo si = mCurrentDragInfo;
        if (mIsExternalDrag) {
            currentDragView = mContent.createAndAddViewForRank(si, mEmptyCellRank);
            // Actually move the item in the database if it was an external drag. Call this
            // before creating the view, so that ShortcutInfo is updated appropriately.
            LauncherModel.addOrMoveItemInDatabase(
                    mLauncher, si, mInfo.id, 0, si.cellX, si.cellY);

            // We only need to update the locations if it doesn't get handled in #onDropCompleted.
            if (d.dragSource != this) {
                updateItemLocationsInDatabaseBatch();
            }
            mIsExternalDrag = false;
        } else {
            currentDragView = mCurrentDragView;
            mContent.addViewForRank(currentDragView, si, mEmptyCellRank);
        }

        if (d.dragView.hasDrawn()) {

            // Temporarily reset the scale such that the animation target gets calculated correctly.
            float scaleX = getScaleX();
            float scaleY = getScaleY();
            setScaleX(1.0f);
            setScaleY(1.0f);
            mLauncher.getDragLayer().animateViewIntoPosition(d.dragView, currentDragView,
                    cleanUpRunnable, null);
            setScaleX(scaleX);
            setScaleY(scaleY);
        } else {
            d.deferDragViewCleanupPostAnimation = false;
            currentDragView.setVisibility(VISIBLE);
        }
        mItemsInvalidated = true;
        rearrangeChildren();

        // Temporarily suppress the listener, as we did all the work already here.
        mSuppressOnAdd = true;
        mInfo.add(si);
        mSuppressOnAdd = false;
        // Clear the drag info, as it is no longer being dragged.
        mCurrentDragInfo = null;
        mDragInProgress = false;

        if (mContent.getPageCount() > 1) {
            // The animation has already been shown while opening the folder.
            mInfo.setOption(FolderInfo.FLAG_MULTI_PAGE_ANIMATION, true, mLauncher);
        }
    }

    // This is used so the item doesn't immediately appear in the folder when added. In one case
    // we need to create the illusion that the item isn't added back to the folder yet, to
    // to correspond to the animation of the icon back into the folder. This is
    public void hideItem(ShortcutInfo info) {
        View v = getViewForInfo(info);
        v.setVisibility(INVISIBLE);
    }
    public void showItem(ShortcutInfo info) {
        View v = getViewForInfo(info);
        v.setVisibility(VISIBLE);
    }

    @Override
    public void onAdd(ShortcutInfo item) {
        // If the item was dropped onto this open folder, we have done the work associated
        // with adding the item to the folder, as indicated by mSuppressOnAdd being set
        if (mSuppressOnAdd) return;
        mContent.createAndAddViewForRank(item, mContent.allocateRankForNewItem(item));
        mItemsInvalidated = true;
        LauncherModel.addOrMoveItemInDatabase(
                mLauncher, item, mInfo.id, 0, item.cellX, item.cellY);
    }

    public void onRemove(ShortcutInfo item) {
        mItemsInvalidated = true;
        // If this item is being dragged from this open folder, we have already handled
        // the work associated with removing the item, so we don't have to do anything here.
        if (item == mCurrentDragInfo) return;
        View v = getViewForInfo(item);
        mContent.removeItem(v);
        if (mState == STATE_ANIMATING) {
            mRearrangeOnClose = true;
        } else {
            rearrangeChildren();
        }
        if (getItemCount() <= 1) {
            if (mInfo.opened) {
                mLauncher.closeFolder(this, true);
            } else {
                replaceFolderWithFinalItem();
            }
        }
    }

    private View getViewForInfo(final ShortcutInfo item) {
        return mContent.iterateOverItems(new ItemOperator() {

            @Override
            public boolean evaluate(ItemInfo info, View view, View parent) {
                return info == item;
            }
        });
    }

    public void onItemsChanged() {
        updateTextViewFocus();
    }

    public void onTitleChanged(CharSequence title) {
    }

    public ArrayList<View> getItemsInReadingOrder() {
        if (mItemsInvalidated) {
            mItemsInReadingOrder.clear();
            mContent.iterateOverItems(new ItemOperator() {

                @Override
                public boolean evaluate(ItemInfo info, View view, View parent) {
                    mItemsInReadingOrder.add(view);
                    return false;
                }
            });
            mItemsInvalidated = false;
        }
        return mItemsInReadingOrder;
    }

    public void getLocationInDragLayer(int[] loc) {
        mLauncher.getDragLayer().getLocationInDragLayer(this, loc);
    }

    public void onFocusChange(View v, boolean hasFocus) {
        if (v == mFolderName) {
            if (hasFocus) {
                startEditingFolderName();
            } else {
                dismissEditingName();
            }
        }
    }

    @Override
    public void getHitRectRelativeToDragLayer(Rect outRect) {
        getHitRect(outRect);
        outRect.left -= mScrollAreaOffset;
        outRect.right += mScrollAreaOffset;
    }

    @Override
    public void fillInLaunchSourceData(View v, Bundle sourceData) {
        // Fill in from the folder icon's launch source provider first
        Stats.LaunchSourceUtils.populateSourceDataFromAncestorProvider(mFolderIcon, sourceData);
        sourceData.putString(Stats.SOURCE_EXTRA_SUB_CONTAINER, Stats.SUB_CONTAINER_FOLDER);
        sourceData.putInt(Stats.SOURCE_EXTRA_SUB_CONTAINER_PAGE, mContent.getCurrentPage());
    }

    private class OnScrollHintListener implements OnAlarmListener {

        private final DragObject mDragObject;

        OnScrollHintListener(DragObject object) {
            mDragObject = object;
        }

        /**
         * Scroll hint has been shown long enough. Now scroll to appropriate page.
         */
        @Override
        public void onAlarm(Alarm alarm) {
            if (mCurrentScrollDir == DragController.SCROLL_LEFT) {
                mContent.scrollLeft();
                mScrollHintDir = DragController.SCROLL_NONE;
            } else if (mCurrentScrollDir == DragController.SCROLL_RIGHT) {
                mContent.scrollRight();
                mScrollHintDir = DragController.SCROLL_NONE;
            } else {
                // This should not happen
                return;
            }
            mCurrentScrollDir = DragController.SCROLL_NONE;

            // Pause drag event until the scrolling is finished
            mScrollPauseAlarm.setOnAlarmListener(new OnScrollFinishedListener(mDragObject));
            mScrollPauseAlarm.setAlarm(DragController.RESCROLL_DELAY);
        }
    }

    private class OnScrollFinishedListener implements OnAlarmListener {

        private final DragObject mDragObject;

        OnScrollFinishedListener(DragObject object) {
            mDragObject = object;
        }

        /**
         * Page scroll is complete.
         */
        @Override
        public void onAlarm(Alarm alarm) {
            // Reorder immediately on page change.
            onDragOver(mDragObject, 1);
        }
    }

    // Compares item position based on rank and position giving priority to the rank.
    public static final Comparator<ItemInfo> ITEM_POS_COMPARATOR = new Comparator<ItemInfo>() {

        @Override
        public int compare(ItemInfo lhs, ItemInfo rhs) {
            if (lhs.rank != rhs.rank) {
                return lhs.rank - rhs.rank;
            } else if (lhs.cellY != rhs.cellY) {
                return lhs.cellY - rhs.cellY;
            } else {
                return lhs.cellX - rhs.cellX;
            }
        }
    };
}