2 * Copyright 2007 ZXing authors
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 package com.google.zxing.qrcode.detector;
19 import com.google.zxing.ResultPoint;
22 * <p>Encapsulates a finder pattern, which are the three square patterns found in
23 * the corners of QR Codes. It also encapsulates a count of similar finder patterns,
24 * as a convenience to the finder's bookkeeping.</p>
28 public final class FinderPattern extends ResultPoint {
30 private final float estimatedModuleSize;
31 private final int count;
33 FinderPattern(float posX, float posY, float estimatedModuleSize) {
34 this(posX, posY, estimatedModuleSize, 1);
37 private FinderPattern(float posX, float posY, float estimatedModuleSize, int count) {
39 this.estimatedModuleSize = estimatedModuleSize;
43 public float getEstimatedModuleSize() {
44 return estimatedModuleSize;
52 void incrementCount() {
58 * <p>Determines if this finder pattern "about equals" a finder pattern at the stated
59 * position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
61 boolean aboutEquals(float moduleSize, float i, float j) {
62 if (Math.abs(i - getY()) <= moduleSize && Math.abs(j - getX()) <= moduleSize) {
63 float moduleSizeDiff = Math.abs(moduleSize - estimatedModuleSize);
64 return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
70 * Combines this object's current estimate of a finder pattern position and module size
71 * with a new estimate. It returns a new {@code FinderPattern} containing a weighted average
74 FinderPattern combineEstimate(float i, float j, float newModuleSize) {
75 int combinedCount = count + 1;
76 float combinedX = (count * getX() + j) / combinedCount;
77 float combinedY = (count * getY() + i) / combinedCount;
78 float combinedModuleSize = (count * estimatedModuleSize + newModuleSize) / combinedCount;
79 return new FinderPattern(combinedX, combinedY, combinedModuleSize, combinedCount);