2 * Copyright 2007 Google Inc.
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.MonochromeBitmapSource;
20 import com.google.zxing.ReaderException;
21 import com.google.zxing.common.BitMatrix;
24 * @author srowen@google.com (Sean Owen)
26 public final class DefaultGridSampler extends GridSampler {
28 protected BitMatrix sampleGrid(MonochromeBitmapSource image,
29 FinderPattern topLeft,
30 FinderPattern topRight,
31 FinderPattern bottomLeft,
32 AlignmentPattern alignmentPattern,
33 int dimension) throws ReaderException {
36 if (alignmentPattern != null) {
37 bottomRightX = alignmentPattern.getX();
38 bottomRightY = alignmentPattern.getY();
40 // Don't have an alignment pattern, just make up the bottom-right point
41 bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
42 bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
45 float dimMinusThree = (float) dimension - 3.5f;
46 PerspectiveTransform transform = PerspectiveTransform.quadrilateralToQuadrilateral(
64 BitMatrix bits = new BitMatrix(dimension);
65 float[] points = new float[dimension << 1];
66 for (int i = 0; i < dimension; i++) {
67 int max = points.length;
68 float iValue = (float) i + 0.5f;
69 for (int j = 0; j < max; j += 2) {
70 points[j] = (float) (j >> 1) + 0.5f;
71 points[j + 1] = iValue;
73 transform.transformPoints(points);
74 // Quick check to see if points transformed to something inside the image;
75 // sufficent to check the endpoints
76 checkEndpoint(image, points);
77 for (int j = 0; j < dimension; j++) {
79 if (image.isBlack((int) points[offset], (int) points[offset + 1])) {