xref: /frameworks/base/core/java/com/android/internal/widget/LockPatternView.java

/*
 * Copyright (C) 2007 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.internal.widget;


import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.os.Debug;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.view.HapticFeedbackConstants;
import android.view.MotionEvent;
import android.view.View;
import android.view.accessibility.AccessibilityManager;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;

import com.android.internal.R;

import java.util.ArrayList;
import java.util.List;

/**
 * Displays and detects the user's unlock attempt, which is a drag of a finger
 * across 9 regions of the screen.
 *
 * Is also capable of displaying a static pattern in "in progress", "wrong" or
 * "correct" states.
 */
public class LockPatternView extends View {
    // Aspect to use when rendering this view
    private static final int ASPECT_SQUARE = 0; // View will be the minimum of width/height
    private static final int ASPECT_LOCK_WIDTH = 1; // Fixed width; height will be minimum of (w,h)
    private static final int ASPECT_LOCK_HEIGHT = 2; // Fixed height; width will be minimum of (w,h)

    private static final boolean PROFILE_DRAWING = false;
    private final CellState[][] mCellStates;

    private final int mDotSize;
    private final int mDotSizeActivated;
    private final int mPathWidth;

    private boolean mDrawingProfilingStarted = false;

    private final Paint mPaint = new Paint();
    private final Paint mPathPaint = new Paint();

    /**
     * How many milliseconds we spend animating each circle of a lock pattern
     * if the animating mode is set.  The entire animation should take this
     * constant * the length of the pattern to complete.
     */
    private static final int MILLIS_PER_CIRCLE_ANIMATING = 700;

    /**
     * This can be used to avoid updating the display for very small motions or noisy panels.
     * It didn't seem to have much impact on the devices tested, so currently set to 0.
     */
    private static final float DRAG_THRESHHOLD = 0.0f;

    private OnPatternListener mOnPatternListener;
    private final ArrayList<Cell> mPattern = new ArrayList<Cell>(9);

    /**
     * Lookup table for the circles of the pattern we are currently drawing.
     * This will be the cells of the complete pattern unless we are animating,
     * in which case we use this to hold the cells we are drawing for the in
     * progress animation.
     */
    private final boolean[][] mPatternDrawLookup = new boolean[3][3];

    /**
     * the in progress point:
     * - during interaction: where the user's finger is
     * - during animation: the current tip of the animating line
     */
    private float mInProgressX = -1;
    private float mInProgressY = -1;

    private long mAnimatingPeriodStart;

    private DisplayMode mPatternDisplayMode = DisplayMode.Correct;
    private boolean mInputEnabled = true;
    private boolean mInStealthMode = false;
    private boolean mEnableHapticFeedback = true;
    private boolean mPatternInProgress = false;

    private float mHitFactor = 0.6f;

    private float mSquareWidth;
    private float mSquareHeight;

    private final Path mCurrentPath = new Path();
    private final Rect mInvalidate = new Rect();
    private final Rect mTmpInvalidateRect = new Rect();

    private int mAspect;
    private int mRegularColor;
    private int mErrorColor;
    private int mSuccessColor;

    private final Interpolator mFastOutSlowInInterpolator;
    private final Interpolator mLinearOutSlowInInterpolator;

    /**
     * Represents a cell in the 3 X 3 matrix of the unlock pattern view.
     */
    public static final class Cell {
        final int row;
        final int column;

        // keep # objects limited to 9
        private static final Cell[][] sCells = createCells();

        private static Cell[][] createCells() {
            Cell[][] res = new Cell[3][3];
            for (int i = 0; i < 3; i++) {
                for (int j = 0; j < 3; j++) {
                    res[i][j] = new Cell(i, j);
                }
            }
            return res;
        }

        /**
         * @param row The row of the cell.
         * @param column The column of the cell.
         */
        private Cell(int row, int column) {
            checkRange(row, column);
            this.row = row;
            this.column = column;
        }

        public int getRow() {
            return row;
        }

        public int getColumn() {
            return column;
        }

        public static Cell of(int row, int column) {
            checkRange(row, column);
            return sCells[row][column];
        }

        private static void checkRange(int row, int column) {
            if (row < 0 || row > 2) {
                throw new IllegalArgumentException("row must be in range 0-2");
            }
            if (column < 0 || column > 2) {
                throw new IllegalArgumentException("column must be in range 0-2");
            }
        }

        @Override
        public String toString() {
            return "(row=" + row + ",clmn=" + column + ")";
        }
    }

    public static class CellState {
        public float scale = 1.0f;
        public float translateY = 0.0f;
        public float alpha = 1.0f;
        public float size;
        public float lineEndX = Float.MIN_VALUE;
        public float lineEndY = Float.MIN_VALUE;
        public ValueAnimator lineAnimator;
     }

    /**
     * How to display the current pattern.
     */
    public enum DisplayMode {

        /**
         * The pattern drawn is correct (i.e draw it in a friendly color)
         */
        Correct,

        /**
         * Animate the pattern (for demo, and help).
         */
        Animate,

        /**
         * The pattern is wrong (i.e draw a foreboding color)
         */
        Wrong
    }

    /**
     * The call back interface for detecting patterns entered by the user.
     */
    public static interface OnPatternListener {

        /**
         * A new pattern has begun.
         */
        void onPatternStart();

        /**
         * The pattern was cleared.
         */
        void onPatternCleared();

        /**
         * The user extended the pattern currently being drawn by one cell.
         * @param pattern The pattern with newly added cell.
         */
        void onPatternCellAdded(List<Cell> pattern);

        /**
         * A pattern was detected from the user.
         * @param pattern The pattern.
         */
        void onPatternDetected(List<Cell> pattern);
    }

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

    public LockPatternView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.LockPatternView);

        final String aspect = a.getString(R.styleable.LockPatternView_aspect);

        if ("square".equals(aspect)) {
            mAspect = ASPECT_SQUARE;
        } else if ("lock_width".equals(aspect)) {
            mAspect = ASPECT_LOCK_WIDTH;
        } else if ("lock_height".equals(aspect)) {
            mAspect = ASPECT_LOCK_HEIGHT;
        } else {
            mAspect = ASPECT_SQUARE;
        }

        setClickable(true);


        mPathPaint.setAntiAlias(true);
        mPathPaint.setDither(true);

        mRegularColor = getResources().getColor(R.color.lock_pattern_view_regular_color);
        mErrorColor = getResources().getColor(R.color.lock_pattern_view_error_color);
        mSuccessColor = getResources().getColor(R.color.lock_pattern_view_success_color);
        mRegularColor = a.getColor(R.styleable.LockPatternView_regularColor, mRegularColor);
        mErrorColor = a.getColor(R.styleable.LockPatternView_errorColor, mErrorColor);
        mSuccessColor = a.getColor(R.styleable.LockPatternView_successColor, mSuccessColor);

        int pathColor = a.getColor(R.styleable.LockPatternView_pathColor, mRegularColor);
        mPathPaint.setColor(pathColor);

        mPathPaint.setStyle(Paint.Style.STROKE);
        mPathPaint.setStrokeJoin(Paint.Join.ROUND);
        mPathPaint.setStrokeCap(Paint.Cap.ROUND);

        mPathWidth = getResources().getDimensionPixelSize(R.dimen.lock_pattern_dot_line_width);
        mPathPaint.setStrokeWidth(mPathWidth);

        mDotSize = getResources().getDimensionPixelSize(R.dimen.lock_pattern_dot_size);
        mDotSizeActivated = getResources().getDimensionPixelSize(
                R.dimen.lock_pattern_dot_size_activated);

        mPaint.setAntiAlias(true);
        mPaint.setDither(true);

        mCellStates = new CellState[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                mCellStates[i][j] = new CellState();
                mCellStates[i][j].size = mDotSize;
            }
        }

        mFastOutSlowInInterpolator =
                AnimationUtils.loadInterpolator(context, android.R.interpolator.fast_out_slow_in);
        mLinearOutSlowInInterpolator =
                AnimationUtils.loadInterpolator(context, android.R.interpolator.linear_out_slow_in);
    }

    public CellState[][] getCellStates() {
        return mCellStates;
    }

    /**
     * @return Whether the view is in stealth mode.
     */
    public boolean isInStealthMode() {
        return mInStealthMode;
    }

    /**
     * @return Whether the view has tactile feedback enabled.
     */
    public boolean isTactileFeedbackEnabled() {
        return mEnableHapticFeedback;
    }

    /**
     * Set whether the view is in stealth mode.  If true, there will be no
     * visible feedback as the user enters the pattern.
     *
     * @param inStealthMode Whether in stealth mode.
     */
    public void setInStealthMode(boolean inStealthMode) {
        mInStealthMode = inStealthMode;
    }

    /**
     * Set whether the view will use tactile feedback.  If true, there will be
     * tactile feedback as the user enters the pattern.
     *
     * @param tactileFeedbackEnabled Whether tactile feedback is enabled
     */
    public void setTactileFeedbackEnabled(boolean tactileFeedbackEnabled) {
        mEnableHapticFeedback = tactileFeedbackEnabled;
    }

    /**
     * Set the call back for pattern detection.
     * @param onPatternListener The call back.
     */
    public void setOnPatternListener(
            OnPatternListener onPatternListener) {
        mOnPatternListener = onPatternListener;
    }

    /**
     * Set the pattern explicitely (rather than waiting for the user to input
     * a pattern).
     * @param displayMode How to display the pattern.
     * @param pattern The pattern.
     */
    public void setPattern(DisplayMode displayMode, List<Cell> pattern) {
        mPattern.clear();
        mPattern.addAll(pattern);
        clearPatternDrawLookup();
        for (Cell cell : pattern) {
            mPatternDrawLookup[cell.getRow()][cell.getColumn()] = true;
        }

        setDisplayMode(displayMode);
    }

    /**
     * Set the display mode of the current pattern.  This can be useful, for
     * instance, after detecting a pattern to tell this view whether change the
     * in progress result to correct or wrong.
     * @param displayMode The display mode.
     */
    public void setDisplayMode(DisplayMode displayMode) {
        mPatternDisplayMode = displayMode;
        if (displayMode == DisplayMode.Animate) {
            if (mPattern.size() == 0) {
                throw new IllegalStateException("you must have a pattern to "
                        + "animate if you want to set the display mode to animate");
            }
            mAnimatingPeriodStart = SystemClock.elapsedRealtime();
            final Cell first = mPattern.get(0);
            mInProgressX = getCenterXForColumn(first.getColumn());
            mInProgressY = getCenterYForRow(first.getRow());
            clearPatternDrawLookup();
        }
        invalidate();
    }

    private void notifyCellAdded() {
        sendAccessEvent(R.string.lockscreen_access_pattern_cell_added);
        if (mOnPatternListener != null) {
            mOnPatternListener.onPatternCellAdded(mPattern);
        }
    }

    private void notifyPatternStarted() {
        sendAccessEvent(R.string.lockscreen_access_pattern_start);
        if (mOnPatternListener != null) {
            mOnPatternListener.onPatternStart();
        }
    }

    private void notifyPatternDetected() {
        sendAccessEvent(R.string.lockscreen_access_pattern_detected);
        if (mOnPatternListener != null) {
            mOnPatternListener.onPatternDetected(mPattern);
        }
    }

    private void notifyPatternCleared() {
        sendAccessEvent(R.string.lockscreen_access_pattern_cleared);
        if (mOnPatternListener != null) {
            mOnPatternListener.onPatternCleared();
        }
    }

    /**
     * Clear the pattern.
     */
    public void clearPattern() {
        resetPattern();
    }

    /**
     * Reset all pattern state.
     */
    private void resetPattern() {
        mPattern.clear();
        clearPatternDrawLookup();
        mPatternDisplayMode = DisplayMode.Correct;
        invalidate();
    }

    /**
     * Clear the pattern lookup table.
     */
    private void clearPatternDrawLookup() {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                mPatternDrawLookup[i][j] = false;
            }
        }
    }

    /**
     * Disable input (for instance when displaying a message that will
     * timeout so user doesn't get view into messy state).
     */
    public void disableInput() {
        mInputEnabled = false;
    }

    /**
     * Enable input.
     */
    public void enableInput() {
        mInputEnabled = true;
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        final int width = w - mPaddingLeft - mPaddingRight;
        mSquareWidth = width / 3.0f;

        final int height = h - mPaddingTop - mPaddingBottom;
        mSquareHeight = height / 3.0f;
    }

    private int resolveMeasured(int measureSpec, int desired)
    {
        int result = 0;
        int specSize = MeasureSpec.getSize(measureSpec);
        switch (MeasureSpec.getMode(measureSpec)) {
            case MeasureSpec.UNSPECIFIED:
                result = desired;
                break;
            case MeasureSpec.AT_MOST:
                result = Math.max(specSize, desired);
                break;
            case MeasureSpec.EXACTLY:
            default:
                result = specSize;
        }
        return result;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        final int minimumWidth = getSuggestedMinimumWidth();
        final int minimumHeight = getSuggestedMinimumHeight();
        int viewWidth = resolveMeasured(widthMeasureSpec, minimumWidth);
        int viewHeight = resolveMeasured(heightMeasureSpec, minimumHeight);

        switch (mAspect) {
            case ASPECT_SQUARE:
                viewWidth = viewHeight = Math.min(viewWidth, viewHeight);
                break;
            case ASPECT_LOCK_WIDTH:
                viewHeight = Math.min(viewWidth, viewHeight);
                break;
            case ASPECT_LOCK_HEIGHT:
                viewWidth = Math.min(viewWidth, viewHeight);
                break;
        }
        // Log.v(TAG, "LockPatternView dimensions: " + viewWidth + "x" + viewHeight);
        setMeasuredDimension(viewWidth, viewHeight);
    }

    /**
     * Determines whether the point x, y will add a new point to the current
     * pattern (in addition to finding the cell, also makes heuristic choices
     * such as filling in gaps based on current pattern).
     * @param x The x coordinate.
     * @param y The y coordinate.
     */
    private Cell detectAndAddHit(float x, float y) {
        final Cell cell = checkForNewHit(x, y);
        if (cell != null) {

            // check for gaps in existing pattern
            Cell fillInGapCell = null;
            final ArrayList<Cell> pattern = mPattern;
            if (!pattern.isEmpty()) {
                final Cell lastCell = pattern.get(pattern.size() - 1);
                int dRow = cell.row - lastCell.row;
                int dColumn = cell.column - lastCell.column;

                int fillInRow = lastCell.row;
                int fillInColumn = lastCell.column;

                if (Math.abs(dRow) == 2 && Math.abs(dColumn) != 1) {
                    fillInRow = lastCell.row + ((dRow > 0) ? 1 : -1);
                }

                if (Math.abs(dColumn) == 2 && Math.abs(dRow) != 1) {
                    fillInColumn = lastCell.column + ((dColumn > 0) ? 1 : -1);
                }

                fillInGapCell = Cell.of(fillInRow, fillInColumn);
            }

            if (fillInGapCell != null &&
                    !mPatternDrawLookup[fillInGapCell.row][fillInGapCell.column]) {
                addCellToPattern(fillInGapCell);
            }
            addCellToPattern(cell);
            if (mEnableHapticFeedback) {
                performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY,
                        HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING
                        | HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING);
            }
            return cell;
        }
        return null;
    }

    private void addCellToPattern(Cell newCell) {
        mPatternDrawLookup[newCell.getRow()][newCell.getColumn()] = true;
        mPattern.add(newCell);
        if (!mInStealthMode) {
            startCellActivatedAnimation(newCell);
        }
        notifyCellAdded();
    }

    private void startCellActivatedAnimation(Cell cell) {
        final CellState cellState = mCellStates[cell.row][cell.column];
        startSizeAnimation(mDotSize, mDotSizeActivated, 96, mLinearOutSlowInInterpolator,
                cellState, new Runnable() {
            @Override
            public void run() {
                startSizeAnimation(mDotSizeActivated, mDotSize, 192, mFastOutSlowInInterpolator,
                        cellState, null);
            }
        });
        startLineEndAnimation(cellState, mInProgressX, mInProgressY,
                getCenterXForColumn(cell.column), getCenterYForRow(cell.row));
    }

    private void startLineEndAnimation(final CellState state,
            final float startX, final float startY, final float targetX, final float targetY) {
        ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, 1);
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                float t = (float) animation.getAnimatedValue();
                state.lineEndX = (1 - t) * startX + t * targetX;
                state.lineEndY = (1 - t) * startY + t * targetY;
                invalidate();
            }
        });
        valueAnimator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                state.lineAnimator = null;
            }
        });
        valueAnimator.setInterpolator(mFastOutSlowInInterpolator);
        valueAnimator.setDuration(100);
        valueAnimator.start();
        state.lineAnimator = valueAnimator;
    }

    private void startSizeAnimation(float start, float end, long duration, Interpolator interpolator,
            final CellState state, final Runnable endRunnable) {
        ValueAnimator valueAnimator = ValueAnimator.ofFloat(start, end);
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                state.size = (float) animation.getAnimatedValue();
                invalidate();
            }
        });
        if (endRunnable != null) {
            valueAnimator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    endRunnable.run();
                }
            });
        }
        valueAnimator.setInterpolator(interpolator);
        valueAnimator.setDuration(duration);
        valueAnimator.start();
    }

    // helper method to find which cell a point maps to
    private Cell checkForNewHit(float x, float y) {

        final int rowHit = getRowHit(y);
        if (rowHit < 0) {
            return null;
        }
        final int columnHit = getColumnHit(x);
        if (columnHit < 0) {
            return null;
        }

        if (mPatternDrawLookup[rowHit][columnHit]) {
            return null;
        }
        return Cell.of(rowHit, columnHit);
    }

    /**
     * Helper method to find the row that y falls into.
     * @param y The y coordinate
     * @return The row that y falls in, or -1 if it falls in no row.
     */
    private int getRowHit(float y) {

        final float squareHeight = mSquareHeight;
        float hitSize = squareHeight * mHitFactor;

        float offset = mPaddingTop + (squareHeight - hitSize) / 2f;
        for (int i = 0; i < 3; i++) {

            final float hitTop = offset + squareHeight * i;
            if (y >= hitTop && y <= hitTop + hitSize) {
                return i;
            }
        }
        return -1;
    }

    /**
     * Helper method to find the column x fallis into.
     * @param x The x coordinate.
     * @return The column that x falls in, or -1 if it falls in no column.
     */
    private int getColumnHit(float x) {
        final float squareWidth = mSquareWidth;
        float hitSize = squareWidth * mHitFactor;

        float offset = mPaddingLeft + (squareWidth - hitSize) / 2f;
        for (int i = 0; i < 3; i++) {

            final float hitLeft = offset + squareWidth * i;
            if (x >= hitLeft && x <= hitLeft + hitSize) {
                return i;
            }
        }
        return -1;
    }

    @Override
    public boolean onHoverEvent(MotionEvent event) {
        if (AccessibilityManager.getInstance(mContext).isTouchExplorationEnabled()) {
            final int action = event.getAction();
            switch (action) {
                case MotionEvent.ACTION_HOVER_ENTER:
                    event.setAction(MotionEvent.ACTION_DOWN);
                    break;
                case MotionEvent.ACTION_HOVER_MOVE:
                    event.setAction(MotionEvent.ACTION_MOVE);
                    break;
                case MotionEvent.ACTION_HOVER_EXIT:
                    event.setAction(MotionEvent.ACTION_UP);
                    break;
            }
            onTouchEvent(event);
            event.setAction(action);
        }
        return super.onHoverEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (!mInputEnabled || !isEnabled()) {
            return false;
        }

        switch(event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                handleActionDown(event);
                return true;
            case MotionEvent.ACTION_UP:
                handleActionUp();
                return true;
            case MotionEvent.ACTION_MOVE:
                handleActionMove(event);
                return true;
            case MotionEvent.ACTION_CANCEL:
                if (mPatternInProgress) {
                    mPatternInProgress = false;
                    resetPattern();
                    notifyPatternCleared();
                }
                if (PROFILE_DRAWING) {
                    if (mDrawingProfilingStarted) {
                        Debug.stopMethodTracing();
                        mDrawingProfilingStarted = false;
                    }
                }
                return true;
        }
        return false;
    }

    private void handleActionMove(MotionEvent event) {
        // Handle all recent motion events so we don't skip any cells even when the device
        // is busy...
        final float radius = mPathWidth;
        final int historySize = event.getHistorySize();
        mTmpInvalidateRect.setEmpty();
        boolean invalidateNow = false;
        for (int i = 0; i < historySize + 1; i++) {
            final float x = i < historySize ? event.getHistoricalX(i) : event.getX();
            final float y = i < historySize ? event.getHistoricalY(i) : event.getY();
            Cell hitCell = detectAndAddHit(x, y);
            final int patternSize = mPattern.size();
            if (hitCell != null && patternSize == 1) {
                mPatternInProgress = true;
                notifyPatternStarted();
            }
            // note current x and y for rubber banding of in progress patterns
            final float dx = Math.abs(x - mInProgressX);
            final float dy = Math.abs(y - mInProgressY);
            if (dx > DRAG_THRESHHOLD || dy > DRAG_THRESHHOLD) {
                invalidateNow = true;
            }

            if (mPatternInProgress && patternSize > 0) {
                final ArrayList<Cell> pattern = mPattern;
                final Cell lastCell = pattern.get(patternSize - 1);
                float lastCellCenterX = getCenterXForColumn(lastCell.column);
                float lastCellCenterY = getCenterYForRow(lastCell.row);

                // Adjust for drawn segment from last cell to (x,y). Radius accounts for line width.
                float left = Math.min(lastCellCenterX, x) - radius;
                float right = Math.max(lastCellCenterX, x) + radius;
                float top = Math.min(lastCellCenterY, y) - radius;
                float bottom = Math.max(lastCellCenterY, y) + radius;

                // Invalidate between the pattern's new cell and the pattern's previous cell
                if (hitCell != null) {
                    final float width = mSquareWidth * 0.5f;
                    final float height = mSquareHeight * 0.5f;
                    final float hitCellCenterX = getCenterXForColumn(hitCell.column);
                    final float hitCellCenterY = getCenterYForRow(hitCell.row);

                    left = Math.min(hitCellCenterX - width, left);
                    right = Math.max(hitCellCenterX + width, right);
                    top = Math.min(hitCellCenterY - height, top);
                    bottom = Math.max(hitCellCenterY + height, bottom);
                }

                // Invalidate between the pattern's last cell and the previous location
                mTmpInvalidateRect.union(Math.round(left), Math.round(top),
                        Math.round(right), Math.round(bottom));
            }
        }
        mInProgressX = event.getX();
        mInProgressY = event.getY();

        // To save updates, we only invalidate if the user moved beyond a certain amount.
        if (invalidateNow) {
            mInvalidate.union(mTmpInvalidateRect);
            invalidate(mInvalidate);
            mInvalidate.set(mTmpInvalidateRect);
        }
    }

    private void sendAccessEvent(int resId) {
        announceForAccessibility(mContext.getString(resId));
    }

    private void handleActionUp() {
        // report pattern detected
        if (!mPattern.isEmpty()) {
            mPatternInProgress = false;
            cancelLineAnimations();
            notifyPatternDetected();
            invalidate();
        }
        if (PROFILE_DRAWING) {
            if (mDrawingProfilingStarted) {
                Debug.stopMethodTracing();
                mDrawingProfilingStarted = false;
            }
        }
    }

    private void cancelLineAnimations() {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                CellState state = mCellStates[i][j];
                if (state.lineAnimator != null) {
                    state.lineAnimator.cancel();
                    state.lineEndX = Float.MIN_VALUE;
                    state.lineEndY = Float.MIN_VALUE;
                }
            }
        }
    }
    private void handleActionDown(MotionEvent event) {
        resetPattern();
        final float x = event.getX();
        final float y = event.getY();
        final Cell hitCell = detectAndAddHit(x, y);
        if (hitCell != null) {
            mPatternInProgress = true;
            mPatternDisplayMode = DisplayMode.Correct;
            notifyPatternStarted();
        } else if (mPatternInProgress) {
            mPatternInProgress = false;
            notifyPatternCleared();
        }
        if (hitCell != null) {
            final float startX = getCenterXForColumn(hitCell.column);
            final float startY = getCenterYForRow(hitCell.row);

            final float widthOffset = mSquareWidth / 2f;
            final float heightOffset = mSquareHeight / 2f;

            invalidate((int) (startX - widthOffset), (int) (startY - heightOffset),
                    (int) (startX + widthOffset), (int) (startY + heightOffset));
        }
        mInProgressX = x;
        mInProgressY = y;
        if (PROFILE_DRAWING) {
            if (!mDrawingProfilingStarted) {
                Debug.startMethodTracing("LockPatternDrawing");
                mDrawingProfilingStarted = true;
            }
        }
    }

    private float getCenterXForColumn(int column) {
        return mPaddingLeft + column * mSquareWidth + mSquareWidth / 2f;
    }

    private float getCenterYForRow(int row) {
        return mPaddingTop + row * mSquareHeight + mSquareHeight / 2f;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        final ArrayList<Cell> pattern = mPattern;
        final int count = pattern.size();
        final boolean[][] drawLookup = mPatternDrawLookup;

        if (mPatternDisplayMode == DisplayMode.Animate) {

            // figure out which circles to draw

            // + 1 so we pause on complete pattern
            final int oneCycle = (count + 1) * MILLIS_PER_CIRCLE_ANIMATING;
            final int spotInCycle = (int) (SystemClock.elapsedRealtime() -
                    mAnimatingPeriodStart) % oneCycle;
            final int numCircles = spotInCycle / MILLIS_PER_CIRCLE_ANIMATING;

            clearPatternDrawLookup();
            for (int i = 0; i < numCircles; i++) {
                final Cell cell = pattern.get(i);
                drawLookup[cell.getRow()][cell.getColumn()] = true;
            }

            // figure out in progress portion of ghosting line

            final boolean needToUpdateInProgressPoint = numCircles > 0
                    && numCircles < count;

            if (needToUpdateInProgressPoint) {
                final float percentageOfNextCircle =
                        ((float) (spotInCycle % MILLIS_PER_CIRCLE_ANIMATING)) /
                                MILLIS_PER_CIRCLE_ANIMATING;

                final Cell currentCell = pattern.get(numCircles - 1);
                final float centerX = getCenterXForColumn(currentCell.column);
                final float centerY = getCenterYForRow(currentCell.row);

                final Cell nextCell = pattern.get(numCircles);
                final float dx = percentageOfNextCircle *
                        (getCenterXForColumn(nextCell.column) - centerX);
                final float dy = percentageOfNextCircle *
                        (getCenterYForRow(nextCell.row) - centerY);
                mInProgressX = centerX + dx;
                mInProgressY = centerY + dy;
            }
            // TODO: Infinite loop here...
            invalidate();
        }

        final Path currentPath = mCurrentPath;
        currentPath.rewind();

        // draw the circles
        for (int i = 0; i < 3; i++) {
            float centerY = getCenterYForRow(i);
            for (int j = 0; j < 3; j++) {
                CellState cellState = mCellStates[i][j];
                float centerX = getCenterXForColumn(j);
                float size = cellState.size * cellState.scale;
                float translationY = cellState.translateY;
                drawCircle(canvas, (int) centerX, (int) centerY + translationY,
                        size, drawLookup[i][j], cellState.alpha);
            }
        }

        // TODO: the path should be created and cached every time we hit-detect a cell
        // only the last segment of the path should be computed here
        // draw the path of the pattern (unless we are in stealth mode)
        final boolean drawPath = !mInStealthMode;

        if (drawPath) {
            mPathPaint.setColor(getCurrentColor(true /* partOfPattern */));

            boolean anyCircles = false;
            float lastX = 0f;
            float lastY = 0f;
            for (int i = 0; i < count; i++) {
                Cell cell = pattern.get(i);

                // only draw the part of the pattern stored in
                // the lookup table (this is only different in the case
                // of animation).
                if (!drawLookup[cell.row][cell.column]) {
                    break;
                }
                anyCircles = true;

                float centerX = getCenterXForColumn(cell.column);
                float centerY = getCenterYForRow(cell.row);
                if (i != 0) {
                    CellState state = mCellStates[cell.row][cell.column];
                    currentPath.rewind();
                    currentPath.moveTo(lastX, lastY);
                    if (state.lineEndX != Float.MIN_VALUE && state.lineEndY != Float.MIN_VALUE) {
                        currentPath.lineTo(state.lineEndX, state.lineEndY);
                    } else {
                        currentPath.lineTo(centerX, centerY);
                    }
                    canvas.drawPath(currentPath, mPathPaint);
                }
                lastX = centerX;
                lastY = centerY;
            }

            // draw last in progress section
            if ((mPatternInProgress || mPatternDisplayMode == DisplayMode.Animate)
                    && anyCircles) {
                currentPath.rewind();
                currentPath.moveTo(lastX, lastY);
                currentPath.lineTo(mInProgressX, mInProgressY);

                mPathPaint.setAlpha((int) (calculateLastSegmentAlpha(
                        mInProgressX, mInProgressY, lastX, lastY) * 255f));
                canvas.drawPath(currentPath, mPathPaint);
            }
        }
    }

    private float calculateLastSegmentAlpha(float x, float y, float lastX, float lastY) {
        float diffX = x - lastX;
        float diffY = y - lastY;
        float dist = (float) Math.sqrt(diffX*diffX + diffY*diffY);
        float frac = dist/mSquareWidth;
        return Math.min(1f, Math.max(0f, (frac - 0.3f) * 4f));
    }

    private int getCurrentColor(boolean partOfPattern) {
        if (!partOfPattern || mInStealthMode || mPatternInProgress) {
            // unselected circle
            return mRegularColor;
        } else if (mPatternDisplayMode == DisplayMode.Wrong) {
            // the pattern is wrong
            return mErrorColor;
        } else if (mPatternDisplayMode == DisplayMode.Correct ||
                mPatternDisplayMode == DisplayMode.Animate) {
            return mSuccessColor;
        } else {
            throw new IllegalStateException("unknown display mode " + mPatternDisplayMode);
        }
    }

    /**
     * @param partOfPattern Whether this circle is part of the pattern.
     */
    private void drawCircle(Canvas canvas, float centerX, float centerY, float size,
            boolean partOfPattern, float alpha) {
        mPaint.setColor(getCurrentColor(partOfPattern));
        mPaint.setAlpha((int) (alpha * 255));
        canvas.drawCircle(centerX, centerY, size/2, mPaint);
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        return new SavedState(superState,
                LockPatternUtils.patternToString(mPattern),
                mPatternDisplayMode.ordinal(),
                mInputEnabled, mInStealthMode, mEnableHapticFeedback);
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        final SavedState ss = (SavedState) state;
        super.onRestoreInstanceState(ss.getSuperState());
        setPattern(
                DisplayMode.Correct,
                LockPatternUtils.stringToPattern(ss.getSerializedPattern()));
        mPatternDisplayMode = DisplayMode.values()[ss.getDisplayMode()];
        mInputEnabled = ss.isInputEnabled();
        mInStealthMode = ss.isInStealthMode();
        mEnableHapticFeedback = ss.isTactileFeedbackEnabled();
    }

    /**
     * The parecelable for saving and restoring a lock pattern view.
     */
    private static class SavedState extends BaseSavedState {

        private final String mSerializedPattern;
        private final int mDisplayMode;
        private final boolean mInputEnabled;
        private final boolean mInStealthMode;
        private final boolean mTactileFeedbackEnabled;

        /**
         * Constructor called from {@link LockPatternView#onSaveInstanceState()}
         */
        private SavedState(Parcelable superState, String serializedPattern, int displayMode,
                boolean inputEnabled, boolean inStealthMode, boolean tactileFeedbackEnabled) {
            super(superState);
            mSerializedPattern = serializedPattern;
            mDisplayMode = displayMode;
            mInputEnabled = inputEnabled;
            mInStealthMode = inStealthMode;
            mTactileFeedbackEnabled = tactileFeedbackEnabled;
        }

        /**
         * Constructor called from {@link #CREATOR}
         */
        private SavedState(Parcel in) {
            super(in);
            mSerializedPattern = in.readString();
            mDisplayMode = in.readInt();
            mInputEnabled = (Boolean) in.readValue(null);
            mInStealthMode = (Boolean) in.readValue(null);
            mTactileFeedbackEnabled = (Boolean) in.readValue(null);
        }

        public String getSerializedPattern() {
            return mSerializedPattern;
        }

        public int getDisplayMode() {
            return mDisplayMode;
        }

        public boolean isInputEnabled() {
            return mInputEnabled;
        }

        public boolean isInStealthMode() {
            return mInStealthMode;
        }

        public boolean isTactileFeedbackEnabled(){
            return mTactileFeedbackEnabled;
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeString(mSerializedPattern);
            dest.writeInt(mDisplayMode);
            dest.writeValue(mInputEnabled);
            dest.writeValue(mInStealthMode);
            dest.writeValue(mTactileFeedbackEnabled);
        }

        @SuppressWarnings({ "unused", "hiding" }) // Found using reflection
        public static final Parcelable.Creator<SavedState> CREATOR =
                new Creator<SavedState>() {
                    @Override
                    public SavedState createFromParcel(Parcel in) {
                        return new SavedState(in);
                    }

                    @Override
                    public SavedState[] newArray(int size) {
                        return new SavedState[size];
                    }
                };
    }
}