diff options
Diffstat (limited to 'libraries/zxing/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java')
| -rw-r--r-- | libraries/zxing/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java | 279 |
1 files changed, 0 insertions, 279 deletions
diff --git a/libraries/zxing/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java b/libraries/zxing/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java deleted file mode 100644 index 3aadf284f..000000000 --- a/libraries/zxing/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java +++ /dev/null @@ -1,279 +0,0 @@ -/*
- * Copyright 2007 ZXing authors
- *
- * 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.google.zxing.qrcode.detector;
-
-import com.google.zxing.NotFoundException;
-import com.google.zxing.ResultPoint;
-import com.google.zxing.ResultPointCallback;
-import com.google.zxing.common.BitMatrix;
-
-import java.util.Vector;
-
-/**
- * <p>This class attempts to find alignment patterns in a QR Code. Alignment patterns look like finder
- * patterns but are smaller and appear at regular intervals throughout the image.</p>
- *
- * <p>At the moment this only looks for the bottom-right alignment pattern.</p>
- *
- * <p>This is mostly a simplified copy of {@link FinderPatternFinder}. It is copied,
- * pasted and stripped down here for maximum performance but does unfortunately duplicate
- * some code.</p>
- *
- * <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
- *
- * @author Sean Owen
- */
-final class AlignmentPatternFinder {
-
- private final BitMatrix image;
- private final Vector possibleCenters;
- private final int startX;
- private final int startY;
- private final int width;
- private final int height;
- private final float moduleSize;
- private final int[] crossCheckStateCount;
- private final ResultPointCallback resultPointCallback;
-
- /**
- * <p>Creates a finder that will look in a portion of the whole image.</p>
- *
- * @param image image to search
- * @param startX left column from which to start searching
- * @param startY top row from which to start searching
- * @param width width of region to search
- * @param height height of region to search
- * @param moduleSize estimated module size so far
- */
- AlignmentPatternFinder(BitMatrix image,
- int startX,
- int startY,
- int width,
- int height,
- float moduleSize,
- ResultPointCallback resultPointCallback) {
- this.image = image;
- this.possibleCenters = new Vector(5);
- this.startX = startX;
- this.startY = startY;
- this.width = width;
- this.height = height;
- this.moduleSize = moduleSize;
- this.crossCheckStateCount = new int[3];
- this.resultPointCallback = resultPointCallback;
- }
-
- /**
- * <p>This method attempts to find the bottom-right alignment pattern in the image. It is a bit messy since
- * it's pretty performance-critical and so is written to be fast foremost.</p>
- *
- * @return {@link AlignmentPattern} if found
- * @throws NotFoundException if not found
- */
- AlignmentPattern find() throws NotFoundException {
- int startX = this.startX;
- int height = this.height;
- int maxJ = startX + width;
- int middleI = startY + (height >> 1);
- // We are looking for black/white/black modules in 1:1:1 ratio;
- // this tracks the number of black/white/black modules seen so far
- int[] stateCount = new int[3];
- for (int iGen = 0; iGen < height; iGen++) {
- // Search from middle outwards
- int i = middleI + ((iGen & 0x01) == 0 ? (iGen + 1) >> 1 : -((iGen + 1) >> 1));
- stateCount[0] = 0;
- stateCount[1] = 0;
- stateCount[2] = 0;
- int j = startX;
- // Burn off leading white pixels before anything else; if we start in the middle of
- // a white run, it doesn't make sense to count its length, since we don't know if the
- // white run continued to the left of the start point
- while (j < maxJ && !image.get(j, i)) {
- j++;
- }
- int currentState = 0;
- while (j < maxJ) {
- if (image.get(j, i)) {
- // Black pixel
- if (currentState == 1) { // Counting black pixels
- stateCount[currentState]++;
- } else { // Counting white pixels
- if (currentState == 2) { // A winner?
- if (foundPatternCross(stateCount)) { // Yes
- AlignmentPattern confirmed = handlePossibleCenter(stateCount, i, j);
- if (confirmed != null) {
- return confirmed;
- }
- }
- stateCount[0] = stateCount[2];
- stateCount[1] = 1;
- stateCount[2] = 0;
- currentState = 1;
- } else {
- stateCount[++currentState]++;
- }
- }
- } else { // White pixel
- if (currentState == 1) { // Counting black pixels
- currentState++;
- }
- stateCount[currentState]++;
- }
- j++;
- }
- if (foundPatternCross(stateCount)) {
- AlignmentPattern confirmed = handlePossibleCenter(stateCount, i, maxJ);
- if (confirmed != null) {
- return confirmed;
- }
- }
-
- }
-
- // Hmm, nothing we saw was observed and confirmed twice. If we had
- // any guess at all, return it.
- if (!possibleCenters.isEmpty()) {
- return (AlignmentPattern) possibleCenters.elementAt(0);
- }
-
- throw NotFoundException.getNotFoundInstance();
- }
-
- /**
- * Given a count of black/white/black pixels just seen and an end position,
- * figures the location of the center of this black/white/black run.
- */
- private static float centerFromEnd(int[] stateCount, int end) {
- return (float) (end - stateCount[2]) - stateCount[1] / 2.0f;
- }
-
- /**
- * @param stateCount count of black/white/black pixels just read
- * @return true iff the proportions of the counts is close enough to the 1/1/1 ratios
- * used by alignment patterns to be considered a match
- */
- private boolean foundPatternCross(int[] stateCount) {
- float moduleSize = this.moduleSize;
- float maxVariance = moduleSize / 2.0f;
- for (int i = 0; i < 3; i++) {
- if (Math.abs(moduleSize - stateCount[i]) >= maxVariance) {
- return false;
- }
- }
- return true;
- }
-
- /**
- * <p>After a horizontal scan finds a potential alignment pattern, this method
- * "cross-checks" by scanning down vertically through the center of the possible
- * alignment pattern to see if the same proportion is detected.</p>
- *
- * @param startI row where an alignment pattern was detected
- * @param centerJ center of the section that appears to cross an alignment pattern
- * @param maxCount maximum reasonable number of modules that should be
- * observed in any reading state, based on the results of the horizontal scan
- * @return vertical center of alignment pattern, or {@link Float#NaN} if not found
- */
- private float crossCheckVertical(int startI, int centerJ, int maxCount,
- int originalStateCountTotal) {
- BitMatrix image = this.image;
-
- int maxI = image.getHeight();
- int[] stateCount = crossCheckStateCount;
- stateCount[0] = 0;
- stateCount[1] = 0;
- stateCount[2] = 0;
-
- // Start counting up from center
- int i = startI;
- while (i >= 0 && image.get(centerJ, i) && stateCount[1] <= maxCount) {
- stateCount[1]++;
- i--;
- }
- // If already too many modules in this state or ran off the edge:
- if (i < 0 || stateCount[1] > maxCount) {
- return Float.NaN;
- }
- while (i >= 0 && !image.get(centerJ, i) && stateCount[0] <= maxCount) {
- stateCount[0]++;
- i--;
- }
- if (stateCount[0] > maxCount) {
- return Float.NaN;
- }
-
- // Now also count down from center
- i = startI + 1;
- while (i < maxI && image.get(centerJ, i) && stateCount[1] <= maxCount) {
- stateCount[1]++;
- i++;
- }
- if (i == maxI || stateCount[1] > maxCount) {
- return Float.NaN;
- }
- while (i < maxI && !image.get(centerJ, i) && stateCount[2] <= maxCount) {
- stateCount[2]++;
- i++;
- }
- if (stateCount[2] > maxCount) {
- return Float.NaN;
- }
-
- int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
- if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
- return Float.NaN;
- }
-
- return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
- }
-
- /**
- * <p>This is called when a horizontal scan finds a possible alignment pattern. It will
- * cross check with a vertical scan, and if successful, will see if this pattern had been
- * found on a previous horizontal scan. If so, we consider it confirmed and conclude we have
- * found the alignment pattern.</p>
- *
- * @param stateCount reading state module counts from horizontal scan
- * @param i row where alignment pattern may be found
- * @param j end of possible alignment pattern in row
- * @return {@link AlignmentPattern} if we have found the same pattern twice, or null if not
- */
- private AlignmentPattern handlePossibleCenter(int[] stateCount, int i, int j) {
- int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
- float centerJ = centerFromEnd(stateCount, j);
- float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1], stateCountTotal);
- if (!Float.isNaN(centerI)) {
- float estimatedModuleSize = (float) (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
- int max = possibleCenters.size();
- for (int index = 0; index < max; index++) {
- AlignmentPattern center = (AlignmentPattern) possibleCenters.elementAt(index);
- // Look for about the same center and module size:
- if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
- return new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
- }
- }
- // Hadn't found this before; save it
- ResultPoint point = new AlignmentPattern(centerJ, centerI, estimatedModuleSize);
- possibleCenters.addElement(point);
- if (resultPointCallback != null) {
- resultPointCallback.foundPossibleResultPoint(point);
- }
- }
- return null;
- }
-
-}
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