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<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 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 }