怎么在Android应用中实现一个图案解锁功能

@Override 
protected void onDraw(Canvas canvas) { 
 final ArrayList 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 float squareWidth = mSquareWidth; 
 final float squareHeight = mSquareHeight; 
 
 float radius = (squareWidth * mDiameterFactor * 0.5f); 
 mPathPaint.setStrokeWidth(radius); 
 
 final Path currentPath = mCurrentPath; 
 currentPath.rewind(); 
 
 // 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 the user is in progress, and 
 // we are in stealth mode) 
 final boolean drawPath = (!mInStealthMode || mPatternDisplayMode == DisplayMode.Wrong); 
 
 // draw the arrows associated with the path (unless the user is in 
 // progress, and 
 // we are in stealth mode) 
 boolean oldFlag = (mPaint.getFlags() & Paint.FILTER_BITMAP_FLAG) != 0; 
 mPaint.setFilterBitmap(true); // draw with higher quality since we 
   // render with transforms 
 // draw the lines 
 if (drawPath) { 
 boolean anyCircles = false; 
 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) { 
 currentPath.moveTo(centerX, centerY); 
 } else { 
 currentPath.lineTo(centerX, centerY); 
 } 
 } 
 
 // add last in progress section 
 if ((mPatternInProgress || mPatternDisplayMode == DisplayMode.Animate) 
 && anyCircles) { 
 currentPath.lineTo(mInProgressX, mInProgressY); 
 } 
 // chang the line color in different DisplayMode 
 if (mPatternDisplayMode == DisplayMode.Wrong) 
 mPathPaint.setColor(Color.RED); 
 else 
 mPathPaint.setColor(Color.YELLOW); 
 canvas.drawPath(currentPath, mPathPaint); 
 } 
 
 // draw the circles 
 final int paddingTop = getPaddingTop(); 
 final int paddingLeft = getPaddingLeft(); 
 
 for (int i = 0; i < 3; i++) { 
 float topY = paddingTop + i * squareHeight; 
 // float centerY = mPaddingTop + i * mSquareHeight + (mSquareHeight 
 // / 2); 
 for (int j = 0; j < 3; j++) { 
 float leftX = paddingLeft + j * squareWidth; 
 drawCircle(canvas, (int) leftX, (int) topY, drawLookup[i][j]); 
 } 
 } 
 
 mPaint.setFilterBitmap(oldFlag); // restore default flag 
} 

/** 
 * Keep track internally of where the user is in choosing a pattern. 
 */ 
 protected enum Stage { 
 // 初始状态 
 Introduction(R.string.lockpattern_recording_intro_header, 
 LeftButtonMode.Cancel, RightButtonMode.ContinueDisabled, 
 ID_EMPTY_MESSAGE, true), 
 // 帮助状态 
 HelpScreen(R.string.lockpattern_settings_help_how_to_record, 
 LeftButtonMode.Gone, RightButtonMode.Ok, ID_EMPTY_MESSAGE, 
 false), 
 // 绘制过短 
 ChoiceTooShort(R.string.lockpattern_recording_incorrect_too_short, 
 LeftButtonMode.Retry, RightButtonMode.ContinueDisabled, 
 ID_EMPTY_MESSAGE, true), 
 // 第一次绘制图案 
 FirstChoiceValid(R.string.lockpattern_pattern_entered_header, 
 LeftButtonMode.Retry, RightButtonMode.Continue, 
 ID_EMPTY_MESSAGE, false), 
 // 需要再次绘制确认 
 NeedToConfirm(R.string.lockpattern_need_to_confirm, 
 LeftButtonMode.Cancel, RightButtonMode.ConfirmDisabled, 
 ID_EMPTY_MESSAGE, true), 
 // 确认出错 
 ConfirmWrong(R.string.lockpattern_need_to_unlock_wrong, 
 LeftButtonMode.Cancel, RightButtonMode.ConfirmDisabled, 
 ID_EMPTY_MESSAGE, true), 
 // 选择确认 
 ChoiceConfirmed(R.string.lockpattern_pattern_confirmed_header, 
 LeftButtonMode.Cancel, RightButtonMode.Confirm, 
 ID_EMPTY_MESSAGE, false); 
 
 /** 
 * @param headerMessage 
 * The message displayed at the top. 
 * @param leftMode 
 * The mode of the left button. 
 * @param rightMode 
 * The mode of the right button. 
 * @param footerMessage 
 * The footer message. 
 * @param patternEnabled 
 * Whether the pattern widget is enabled. 
 */ 
 Stage(int headerMessage, LeftButtonMode leftMode, 
 RightButtonMode rightMode, int footerMessage, 
 boolean patternEnabled) { 
 this.headerMessage = headerMessage; 
 this.leftMode = leftMode; 
 this.rightMode = rightMode; 
 this.footerMessage = footerMessage; 
 this.patternEnabled = patternEnabled; 
 } 
 
 final int headerMessage; 
 final LeftButtonMode leftMode; 
 final RightButtonMode rightMode; 
 final int footerMessage; 
 final boolean patternEnabled; 
 } 

/** 
 * The states of the left footer button. 
 */ 
 enum LeftButtonMode { 
 // 取消 
 Cancel(android.R.string.cancel, true), 
 // 取消时禁用 
 CancelDisabled(android.R.string.cancel, false), 
 // 重试 
 Retry(R.string.lockpattern_retry_button_text, true), 
 // 重试时禁用 
 RetryDisabled(R.string.lockpattern_retry_button_text, false), 
 // 消失 
 Gone(ID_EMPTY_MESSAGE, false); 
 
 /** 
 * @param text 
 * The displayed text for this mode. 
 * @param enabled 
 * Whether the button should be enabled. 
 */ 
 LeftButtonMode(int text, boolean enabled) { 
 this.text = text; 
 this.enabled = enabled; 
 } 
 
 final int text; 
 final boolean enabled; 
 } 
 
 /** 
 * The states of the right button. 
 */ 
 enum RightButtonMode { 
 // 继续 
 Continue(R.string.lockpattern_continue_button_text, true), 
 //继续时禁用 
 ContinueDisabled(R.string.lockpattern_continue_button_text, false), 
 //确认 
 Confirm(R.string.lockpattern_confirm_button_text, true), 
 //确认是禁用 
 ConfirmDisabled(R.string.lockpattern_confirm_button_text, false), 
 //OK 
 Ok(android.R.string.ok, true); 
 
 /** 
 * @param text 
 * The displayed text for this mode. 
 * @param enabled 
 * Whether the button should be enabled. 
 */ 
 RightButtonMode(int text, boolean enabled) { 
 this.text = text; 
 this.enabled = enabled; 
 } 
 
 final int text; 
 final boolean enabled; 
 } 

/** 
 * Serialize a pattern. 加密 
 * 
 * @param pattern 
 * The pattern. 
 * @return The pattern in string form. 
 */ 
public static String patternToString(List pattern) { 
 if (pattern == null) { 
 return ""; 
 } 
 final int patternSize = pattern.size(); 
 
 byte[] res = new byte[patternSize]; 
 for (int i = 0; i < patternSize; i++) { 
 LockPatternView.Cell cell = pattern.get(i); 
 res[i] = (byte) (cell.getRow() * 3 + cell.getColumn()); 
 } 
 return new String(res); 
} 
 
/** 
 * Save a lock pattern. 
 * 
 * @param pattern 
 * The new pattern to save. 
 * @param isFallback 
 * Specifies if this is a fallback to biometric weak 
 */ 
public void saveLockPattern(List pattern) { 
 // Compute the hash 
 final byte[] hash = LockPatternUtils.patternToHash(pattern); 
 try { 
 // Write the hash to file 
 RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, 
 "rwd"); 
 // Truncate the file if pattern is null, to clear the lock 
 if (pattern == null) { 
 raf.setLength(0); 
 } else { 
 raf.write(hash, 0, hash.length); 
 } 
 raf.close(); 
 } catch (FileNotFoundException fnfe) { 
 // Cant do much, unless we want to fail over to using the settings 
 // provider 
 Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename); 
 } catch (IOException ioe) { 
 // Cant do much 
 Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename); 
 } 
} 
 
/* 
 * Generate an SHA-1 hash for the pattern. Not the most secure, but it is at 
 * least a second level of protection. First level is that the file is in a 
 * location only readable by the system process. 
 * 
 * @param pattern the gesture pattern. 
 * 
 * @return the hash of the pattern in a byte array. 
 */ 
private static byte[] patternToHash(List pattern) { 
 if (pattern == null) { 
 return null; 
 } 
 
 final int patternSize = pattern.size(); 
 byte[] res = new byte[patternSize]; 
 for (int i = 0; i < patternSize; i++) { 
 LockPatternView.Cell cell = pattern.get(i); 
 res[i] = (byte) (cell.getRow() * 3 + cell.getColumn()); 
 } 
 try { 
 MessageDigest md = MessageDigest.getInstance("SHA-1"); 
 byte[] hash = md.digest(res); 
 return hash; 
 } catch (NoSuchAlgorithmException nsa) { 
 return res; 
 } 
} 
 
/** 
 * Check to see if a pattern matches the saved pattern. If no pattern 
 * exists, always returns true. 
 * 
 * @param pattern 
 * The pattern to check. 
 * @return Whether the pattern matches the stored one. 
 */ 
public boolean checkPattern(List pattern) { 
 try { 
 // Read all the bytes from the file 
 RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, 
 "r"); 
 final byte[] stored = new byte[(int) raf.length()]; 
 int got = raf.read(stored, 0, stored.length); 
 raf.close(); 
 if (got <= 0) { 
 return true; 
 } 
 // Compare the hash from the file with the entered pattern's hash 
 return Arrays.equals(stored, 
 LockPatternUtils.patternToHash(pattern)); 
 } catch (FileNotFoundException fnfe) { 
 return true; 
 } catch (IOException ioe) { 
 return true; 
 } 
}