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More javadoc
git-svn-id: https://zxing.googlecode.com/svn/trunk@14 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen
parent
d6cfb083a1
commit
0aeb2f672c
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@ -19,6 +19,9 @@ package com.google.zxing.qrcode.detector;
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import com.google.zxing.ResultPoint;
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/**
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* <p>Encapsulates an alignment pattern, which are the smaller square patterns found in
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* all but the simplest QR Codes.</p>
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*
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* @author srowen@google.com (Sean Owen)
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*/
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public final class AlignmentPattern implements ResultPoint {
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@ -45,6 +48,10 @@ public final class AlignmentPattern implements ResultPoint {
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return estimatedModuleSize;
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}
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/**
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* <p>Determines if this alignment pattern "about equals" an alignment pattern at the stated
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* position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
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*/
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boolean aboutEquals(float moduleSize, float i, float j) {
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return
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Math.abs(i - posY) <= moduleSize &&
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@ -23,8 +23,15 @@ import com.google.zxing.common.BitArray;
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import java.util.Vector;
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/**
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* <p>This class attempts to find alignment patterns in a QR Code. Alignment patterns look like finder
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* patterns but are smaller and appear at regular intervals throughout the image.</p>
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*
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* <p>At the moment this only looks for the bottom-right alignment pattern.</p>
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*
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* <p>This is mostly a simplified copy of {@link FinderPatternFinder}. It is copied,
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* pasted and stripped down here for maximum performance but does unfortunately duplicate
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* some code.</p>
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*
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* <p>This class is not thread-safe.</p>
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*
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* @author srowen@google.com (Sean Owen)
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@ -39,6 +46,16 @@ final class AlignmentPatternFinder {
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private final int height;
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private final float moduleSize;
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/**
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* <p>Creates a finder that will look in a portion of the whole image.</p>
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*
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* @param image image to search
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* @param startX left column from which to start searching
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* @param startY top row from which to start searching
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* @param width width of region to search
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* @param height height of region to search
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* @param moduleSize estimated module size so far
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*/
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AlignmentPatternFinder(MonochromeBitmapSource image,
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int startX,
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int startY,
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@ -54,17 +71,25 @@ final class AlignmentPatternFinder {
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this.moduleSize = moduleSize;
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}
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/**
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* <p>This method attempts to find the bottom-right alignment pattern in the image. It is a bit messy since
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* it's pretty performance-critical and so is written to be fast foremost.</p>
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*
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* @return {@link AlignmentPattern} if found
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* @throws ReaderException if not found
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*/
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AlignmentPattern find() throws ReaderException {
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int startX = this.startX;
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int height = this.height;
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int maxJ = startX + width;
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int middleI = startY + (height >> 1);
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BitArray luminanceRow = new BitArray(width);
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int[] stateCount = new int[3]; // looking for 1 1 1
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// We are looking for black/white/black modules in 1:1:1 ratio;
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// this tracks the number of black/white/black modules seen so far
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int[] stateCount = new int[3];
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for (int iGen = 0; iGen < height; iGen++) {
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// Search from middle outwards
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int i = middleI +
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((iGen & 0x01) == 0 ? ((iGen + 1) >> 1) : -((iGen + 1) >> 1));
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int i = middleI + ((iGen & 0x01) == 0 ? ((iGen + 1) >> 1) : -((iGen + 1) >> 1));
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image.getBlackRow(i, luminanceRow, startX, width);
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stateCount[0] = 0;
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stateCount[1] = 0;
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@ -85,8 +110,7 @@ final class AlignmentPatternFinder {
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} else { // Counting white pixels
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if (currentState == 2) { // A winner?
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if (foundPatternCross(stateCount)) { // Yes
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AlignmentPattern confirmed =
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handlePossibleCenter(stateCount, i, j);
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AlignmentPattern confirmed = handlePossibleCenter(stateCount, i, j);
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if (confirmed != null) {
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return confirmed;
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}
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@ -125,10 +149,19 @@ final class AlignmentPatternFinder {
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throw new ReaderException("Could not find alignment pattern");
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}
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/**
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* Given a count of black/white/black pixels just seen and an end position,
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* figures the location of the center of this black/white/black run.
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*/
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private static float centerFromEnd(int[] stateCount, int end) {
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return (float) (end - stateCount[2]) - stateCount[1] / 2.0f;
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}
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/**
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* @param stateCount count of black/white/black pixels just read
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* @return true iff the proportions of the counts is close enough to the 1/1/1 ratios
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* used by alignment patterns to be considered a match
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*/
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private boolean foundPatternCross(int[] stateCount) {
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float moduleSize = this.moduleSize;
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for (int i = 0; i < 3; i++) {
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@ -139,16 +172,30 @@ final class AlignmentPatternFinder {
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return true;
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}
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/**
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* <p>After a horizontal scan finds a potential alignment pattern, this method
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* "cross-checks" by scanning down vertically through the center of the possible
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* alignment pattern to see if the same proportion is detected.</p>
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*
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* @param startI row where an alignment pattern was detected
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* @param centerJ center of the section that appears to cross an alignment pattern
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* @param maxCount maximum reasonable number of modules that should be
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* observed in any reading state, based on the results of the horizontal scan
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* @return vertical center of alignment pattern, or {@link Float#NaN} if not found
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*/
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private float crossCheckVertical(int startI, int centerJ, int maxCount) {
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MonochromeBitmapSource image = this.image;
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int maxI = image.getHeight();
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int[] stateCount = new int[3];
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// Start counting up from center
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int i = startI;
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while (i >= 0 && image.isBlack(centerJ, i) && stateCount[1] <= maxCount) {
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stateCount[1]++;
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i--;
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}
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// If already too many modules in this state or ran off the edge:
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if (i < 0 || stateCount[1] > maxCount) {
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return Float.NaN;
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}
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@ -160,17 +207,16 @@ final class AlignmentPatternFinder {
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return Float.NaN;
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}
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// Now also count down from center
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i = startI + 1;
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while (i < maxI && image.isBlack(centerJ, i) &&
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stateCount[1] <= maxCount) {
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while (i < maxI && image.isBlack(centerJ, i) && stateCount[1] <= maxCount) {
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stateCount[1]++;
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i++;
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}
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if (i == maxI || stateCount[1] > maxCount) {
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return Float.NaN;
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}
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while (i < maxI && !image.isBlack(centerJ, i) &&
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stateCount[2] <= maxCount) {
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while (i < maxI && !image.isBlack(centerJ, i) && stateCount[2] <= maxCount) {
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stateCount[2]++;
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i++;
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}
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@ -178,21 +224,25 @@ final class AlignmentPatternFinder {
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return Float.NaN;
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}
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return
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foundPatternCross(stateCount) ?
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centerFromEnd(stateCount, i) :
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Float.NaN;
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return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
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}
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private AlignmentPattern handlePossibleCenter(int[] stateCount,
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int i,
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int j) {
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/**
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* <p>This is called when a horizontal scan finds a possible alignment pattern. It will
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* cross check with a vertical scan, and if successful, will see if this pattern had been
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* found on a previous horizontal scan. If so, we consider it confirmed and conclude we have
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* found the alignment pattern.</p>
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*
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* @param stateCount reading state module counts from horizontal scan
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* @param i row where alignment pattern may be found
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* @param j end of possible alignment pattern in row
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* @return {@link AlignmentPattern} if we have found the same pattern twice, or null if not
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*/
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private AlignmentPattern handlePossibleCenter(int[] stateCount, int i, int j) {
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float centerJ = centerFromEnd(stateCount, j);
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float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1]);
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if (!Float.isNaN(centerI)) {
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float estimatedModuleSize = (float) (stateCount[0] +
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stateCount[1] +
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stateCount[2]) / 3.0f;
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float estimatedModuleSize = (float) (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
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int max = possibleCenters.size();
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for (int index = 0; index < max; index++) {
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AlignmentPattern center = (AlignmentPattern) possibleCenters.elementAt(index);
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@ -23,6 +23,9 @@ import com.google.zxing.common.BitMatrix;
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import com.google.zxing.qrcode.decoder.Version;
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/**
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* <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
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* is rotated or skewed, or partially obscured.</p>
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*
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* @author srowen@google.com (Sean Owen)
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*/
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public final class Detector {
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@ -33,6 +36,12 @@ public final class Detector {
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this.image = image;
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}
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/**
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* <p>Detects a QR Code in an image, simply.</p>
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*
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* @return {@link DetectorResult} encapsulating results of detecting a QR Code
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* @throws ReaderException if no QR Code can be found
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*/
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public DetectorResult detect() throws ReaderException {
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MonochromeBitmapSource image = this.image;
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@ -71,7 +80,7 @@ public final class Detector {
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estAlignmentY,
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(float) i);
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break;
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} catch (ReaderException de) {
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} catch (ReaderException re) {
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// try next round
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}
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}
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@ -82,12 +91,7 @@ public final class Detector {
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}
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GridSampler sampler = GridSampler.getInstance();
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BitMatrix bits = sampler.sampleGrid(image,
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topLeft,
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topRight,
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bottomLeft,
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alignmentPattern,
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dimension);
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BitMatrix bits = sampler.sampleGrid(image, topLeft, topRight, bottomLeft, alignmentPattern, dimension);
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/*
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try {
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@ -104,8 +108,7 @@ public final class Detector {
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}
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}
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}
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ImageIO.write(outImage, "PNG",
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new File("/home/srowen/out.png"));
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ImageIO.write(outImage, "PNG", new File("/tmp/out.png"));
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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@ -120,15 +123,16 @@ public final class Detector {
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return new DetectorResult(bits, points);
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}
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/**
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* <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
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* of the finder patterns and estimated module size.</p>
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*/
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private static int computeDimension(ResultPoint topLeft,
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ResultPoint topRight,
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ResultPoint bottomLeft,
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float moduleSize)
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throws ReaderException {
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int tltrCentersDimension =
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round(FinderPatternFinder.distance(topLeft, topRight) / moduleSize);
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int tlblCentersDimension =
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round(FinderPatternFinder.distance(topLeft, bottomLeft) / moduleSize);
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float moduleSize) throws ReaderException {
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int tltrCentersDimension = round(FinderPatternFinder.distance(topLeft, topRight) / moduleSize);
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int tlblCentersDimension = round(FinderPatternFinder.distance(topLeft, bottomLeft) / moduleSize);
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int dimension = ((tltrCentersDimension + tlblCentersDimension) >> 1) + 7;
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switch (dimension & 0x03) { // mod 4
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case 0:
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@ -144,16 +148,22 @@ public final class Detector {
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return dimension;
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}
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private float calculateModuleSize(ResultPoint topLeft,
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ResultPoint topRight,
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ResultPoint bottomLeft) {
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/**
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* <p>Computes an average estimated module size based on estimated derived from the positions
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* of the three finder patterns.</p>
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*/
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private float calculateModuleSize(ResultPoint topLeft, ResultPoint topRight, ResultPoint bottomLeft) {
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// Take the average
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return (calculateModuleSizeOneWay(topLeft, topRight) +
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calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0f;
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}
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private float calculateModuleSizeOneWay(ResultPoint pattern,
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ResultPoint otherPattern) {
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/**
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* <p>Estimates module size based on two finder patterns -- it uses
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* {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the
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* width of each, measuring along the axis between their centers.</p>
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*/
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private float calculateModuleSizeOneWay(ResultPoint pattern, ResultPoint otherPattern) {
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float moduleSizeEst1 = sizeOfBlackWhiteBlackRunBothWays((int) pattern.getX(),
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(int) pattern.getY(),
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(int) otherPattern.getX(),
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@ -173,12 +183,25 @@ public final class Detector {
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return (moduleSizeEst1 + moduleSizeEst2) / 14.0f;
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}
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/**
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* See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of
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* a finder pattern by looking for a black-white-black run from the center in the direction
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* of another point (another finder pattern center), and in the opposite direction too.</p>
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*/
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private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY) {
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float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
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result += sizeOfBlackWhiteBlackRun(fromX, fromY, fromX - (toX - fromX), fromY - (toY - fromY));
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return result - 1.0f; // -1 because we counted the middle pixel twice
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}
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/**
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* <p>This method traces a line from a point in the image, in the direction towards another point.
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* It begins in a black region, and keeps going until it finds white, then black, then white again.
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* It reports the distance from the start to this point.</p>
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*
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* <p>This is used when figuring out how wide a finder pattern is, when the finder pattern
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* may be skewed or rotated.</p>
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*/
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private float sizeOfBlackWhiteBlackRun(int fromX, int fromY, int toX, int toY) {
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// Mild variant of Bresenham's algorithm;
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// see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
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@ -227,6 +250,17 @@ public final class Detector {
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return Float.NaN;
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}
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/**
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* <p>Attempts to locate an alignment pattern in a limited region of the image, which is
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* guessed to contain it. This method uses {@link AlignmentPattern}.</p>
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*
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* @param overallEstModuleSize estimated module size so far
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* @param estAlignmentX x coordinate of center of area probably containing alignment pattern
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* @param estAlignmentY y coordinate of above
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* @param allowanceFactor number of pixels in all directons to search from the center
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* @return {@link AlignmentPattern} if found, or null otherwise
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* @throws ReaderException if an unexpected error occurs during detection
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*/
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private AlignmentPattern findAlignmentInRegion(float overallEstModuleSize,
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int estAlignmentX,
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int estAlignmentY,
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@ -236,11 +270,9 @@ public final class Detector {
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// should be
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int allowance = (int) (allowanceFactor * overallEstModuleSize);
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int alignmentAreaLeftX = Math.max(0, estAlignmentX - allowance);
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int alignmentAreaRightX = Math.min(image.getWidth() - 1,
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estAlignmentX + allowance);
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int alignmentAreaRightX = Math.min(image.getWidth() - 1, estAlignmentX + allowance);
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int alignmentAreaTopY = Math.max(0, estAlignmentY - allowance);
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int alignmentAreaBottomY = Math.min(image.getHeight() - 1,
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estAlignmentY + allowance);
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int alignmentAreaBottomY = Math.min(image.getHeight() - 1, estAlignmentY + allowance);
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AlignmentPatternFinder alignmentFinder =
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new AlignmentPatternFinder(
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@ -254,7 +286,8 @@ public final class Detector {
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}
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/**
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* Ends up being a bit faster than Math.round()
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* Ends up being a bit faster than Math.round(). This merely rounds its argument to the nearest int,
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* where x.5 rounds up.
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*/
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private static int round(float d) {
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return (int) (d + 0.5f);
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@ -19,6 +19,10 @@ package com.google.zxing.qrcode.detector;
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import com.google.zxing.ResultPoint;
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/**
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* <p>Encapsulates a finder pattern, which are the three square patterns found in
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* the corners of QR Codes. It also encapsulates a count of similar finder patterns,
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* as a convenience to {@link FinderPatternFinder}'s bookkeeping.</p>
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*
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* @author srowen@google.com (Sean Owen)
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*/
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public final class FinderPattern implements ResultPoint {
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@ -55,6 +59,10 @@ public final class FinderPattern implements ResultPoint {
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this.count++;
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}
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/**
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* <p>Determines if this finder pattern "about equals" a finder pattern at the stated
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* position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
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*/
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boolean aboutEquals(float moduleSize, float i, float j) {
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return Math.abs(i - posY) <= moduleSize &&
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Math.abs(j - posX) <= moduleSize &&
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|
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@ -26,6 +26,9 @@ import com.google.zxing.common.Comparator;
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import java.util.Vector;
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/**
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* <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
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* markers at three corners of a QR Code.</p>
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*
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* <p>This class is not thread-safe and should not be reused.</p>
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*
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* @author srowen@google.com (Sean Owen)
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@ -39,6 +42,11 @@ final class FinderPatternFinder {
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private final Vector possibleCenters;
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private boolean hasSkipped;
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/**
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* <p>Creates a finder that will search the image for three finder patterns.</p>
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*
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* @param image image to search
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*/
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FinderPatternFinder(MonochromeBitmapSource image) {
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this.image = image;
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this.possibleCenters = new Vector(5);
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|
|
@ -47,13 +55,16 @@ final class FinderPatternFinder {
|
|||
FinderPatternInfo find() throws ReaderException {
|
||||
int maxI = image.getHeight();
|
||||
int maxJ = image.getWidth();
|
||||
int[] stateCount = new int[5]; // looking for 1 1 3 1 1
|
||||
// We are looking for black/white/black/white/black modules in
|
||||
// 1:1:3:1:1 ratio; this tracks the number of such modules seen so far
|
||||
int[] stateCount = new int[5];
|
||||
boolean done = false;
|
||||
// We can afford to examine every few lines until we've started finding
|
||||
// the patterns
|
||||
int iSkip = BIG_SKIP;
|
||||
for (int i = iSkip - 1; i < maxI && !done; i += iSkip) {
|
||||
BitArray luminanceRow = image.getBlackRow(i, null, 0, maxJ);
|
||||
// Get a row of black/white values
|
||||
BitArray blackRow = image.getBlackRow(i, null, 0, maxJ);
|
||||
stateCount[0] = 0;
|
||||
stateCount[1] = 0;
|
||||
stateCount[2] = 0;
|
||||
|
|
@ -61,7 +72,7 @@ final class FinderPatternFinder {
|
|||
stateCount[4] = 0;
|
||||
int currentState = 0;
|
||||
for (int j = 0; j < maxJ; j++) {
|
||||
if (luminanceRow.get(j)) {
|
||||
if (blackRow.get(j)) {
|
||||
// Black pixel
|
||||
if ((currentState & 1) == 1) { // Counting white pixels
|
||||
currentState++;
|
||||
|
|
@ -71,8 +82,7 @@ final class FinderPatternFinder {
|
|||
if ((currentState & 1) == 0) { // Counting black pixels
|
||||
if (currentState == 4) { // A winner?
|
||||
if (foundPatternCross(stateCount)) { // Yes
|
||||
boolean confirmed =
|
||||
handlePossibleCenter(stateCount, i, j);
|
||||
boolean confirmed = handlePossibleCenter(stateCount, i, j);
|
||||
if (confirmed) {
|
||||
iSkip = 1; // Go back to examining each line
|
||||
if (hasSkipped) {
|
||||
|
|
@ -96,7 +106,7 @@ final class FinderPatternFinder {
|
|||
// Advance to next black pixel
|
||||
do {
|
||||
j++;
|
||||
} while (j < maxJ && !luminanceRow.get(j));
|
||||
} while (j < maxJ && !blackRow.get(j));
|
||||
j--; // back up to that last white pixel
|
||||
}
|
||||
// Clear state to start looking again
|
||||
|
|
@ -141,14 +151,22 @@ final class FinderPatternFinder {
|
|||
totalModuleSize += patternInfo[i].getEstimatedModuleSize();
|
||||
}
|
||||
|
||||
return new FinderPatternInfo(totalModuleSize / (float) patternInfo.length,
|
||||
patternInfo);
|
||||
return new FinderPatternInfo(totalModuleSize / (float) patternInfo.length, patternInfo);
|
||||
}
|
||||
|
||||
/**
|
||||
* Given a count of black/white/black/white/black pixels just seen and an end position,
|
||||
* figures the location of the center of this run.
|
||||
*/
|
||||
private static float centerFromEnd(int[] stateCount, int end) {
|
||||
return (float) (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0f;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param stateCount count of black/white/black/white/black pixels just read
|
||||
* @return true iff the proportions of the counts is close enough to the 1/13/1/1 ratios
|
||||
* used by finder patterns to be considered a match
|
||||
*/
|
||||
private static boolean foundPatternCross(int[] stateCount) {
|
||||
int totalModuleSize = 0;
|
||||
for (int i = 0; i < 5; i++) {
|
||||
|
|
@ -162,20 +180,31 @@ final class FinderPatternFinder {
|
|||
}
|
||||
int moduleSize = totalModuleSize / 7;
|
||||
// Allow less than 50% deviance from 1-1-3-1-1 pattern
|
||||
return
|
||||
Math.abs(moduleSize - stateCount[0]) << 1 <= moduleSize &&
|
||||
return Math.abs(moduleSize - stateCount[0]) << 1 <= moduleSize &&
|
||||
Math.abs(moduleSize - stateCount[1]) << 1 <= moduleSize &&
|
||||
Math.abs(3 * moduleSize - stateCount[2]) << 1 <= 3 * moduleSize &&
|
||||
Math.abs(moduleSize - stateCount[3]) << 1 <= moduleSize &&
|
||||
Math.abs(moduleSize - stateCount[4]) << 1 <= moduleSize;
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>After a horizontal scan finds a potential finder pattern, this method
|
||||
* "cross-checks" by scanning down vertically through the center of the possible
|
||||
* finder pattern to see if the same proportion is detected.</p>
|
||||
*
|
||||
* @param startI row where a finder pattern was detected
|
||||
* @param centerJ center of the section that appears to cross a finder 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 finder pattern, or {@link Float#NaN} if not found
|
||||
*/
|
||||
private float crossCheckVertical(int startI, int centerJ, int maxCount) {
|
||||
MonochromeBitmapSource image = this.image;
|
||||
|
||||
int maxI = image.getHeight();
|
||||
int[] stateCount = new int[5];
|
||||
|
||||
// Start counting up from center
|
||||
int i = startI;
|
||||
while (i >= 0 && image.isBlack(centerJ, i)) {
|
||||
stateCount[2]++;
|
||||
|
|
@ -200,6 +229,7 @@ final class FinderPatternFinder {
|
|||
return Float.NaN;
|
||||
}
|
||||
|
||||
// Now also count down from center
|
||||
i = startI + 1;
|
||||
while (i < maxI && image.isBlack(centerJ, i)) {
|
||||
stateCount[2]++;
|
||||
|
|
@ -226,6 +256,11 @@ final class FinderPatternFinder {
|
|||
return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>Like {@link #crossCheckVertical(int, int, int)}, and in fact is basically identical,
|
||||
* except it reads horizontally instead of vertically. This is used to cross-cross
|
||||
* check a vertical cross check and locate the real center of the alignment pattern.</p>
|
||||
*/
|
||||
private float crossCheckHorizontal(int startJ, int centerI, int maxCount) {
|
||||
MonochromeBitmapSource image = this.image;
|
||||
|
||||
|
|
@ -244,7 +279,6 @@ final class FinderPatternFinder {
|
|||
stateCount[1]++;
|
||||
j--;
|
||||
}
|
||||
// If already too many modules in this state or ran off the edge:
|
||||
if (j < 0 || stateCount[1] > maxCount) {
|
||||
return Float.NaN;
|
||||
}
|
||||
|
|
@ -282,6 +316,22 @@ final class FinderPatternFinder {
|
|||
return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : 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, ah, cross-cross-check
|
||||
* with another horizontal scan. This is needed primarily to locate the real horizontal
|
||||
* center of the pattern in cases of extreme skew.</p>
|
||||
*
|
||||
* <p>If that succeeds the finder pattern location is added to a list that tracks
|
||||
* the number of times each location has been nearly-matched as a finder pattern.
|
||||
* Each additional find is more evidence that the location is in fact a finder
|
||||
* pattern center
|
||||
*
|
||||
* @param stateCount reading state module counts from horizontal scan
|
||||
* @param i row where finder pattern may be found
|
||||
* @param j end of possible finder pattern in row
|
||||
* @return true if a finder pattern candidate was found this time
|
||||
*/
|
||||
private boolean handlePossibleCenter(int[] stateCount,
|
||||
int i,
|
||||
int j) {
|
||||
|
|
@ -291,11 +341,8 @@ final class FinderPatternFinder {
|
|||
// Re-cross check
|
||||
centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2]);
|
||||
if (!Float.isNaN(centerJ)) {
|
||||
float estimatedModuleSize = (float) (stateCount[0] +
|
||||
stateCount[1] +
|
||||
stateCount[2] +
|
||||
stateCount[3] +
|
||||
stateCount[4]) / 7.0f;
|
||||
float estimatedModuleSize =
|
||||
(float) (stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4]) / 7.0f;
|
||||
boolean found = false;
|
||||
int max = possibleCenters.size();
|
||||
for (int index = 0; index < max; index++) {
|
||||
|
|
@ -308,8 +355,7 @@ final class FinderPatternFinder {
|
|||
}
|
||||
}
|
||||
if (!found) {
|
||||
possibleCenters.addElement(
|
||||
new FinderPattern(centerJ, centerI, estimatedModuleSize));
|
||||
possibleCenters.addElement(new FinderPattern(centerJ, centerI, estimatedModuleSize));
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
|
@ -317,6 +363,12 @@ final class FinderPatternFinder {
|
|||
return false;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return number of rows we could safely skip during scanning, based on the first
|
||||
* two finder patterns that have been located. In some cases their position will
|
||||
* allow us to infer that the third pattern must lie below a certain point farther
|
||||
* down in the image.
|
||||
*/
|
||||
private int findRowSkip() {
|
||||
int max = possibleCenters.size();
|
||||
if (max <= 1) {
|
||||
|
|
@ -343,6 +395,10 @@ final class FinderPatternFinder {
|
|||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return true iff we have found at least 3 finder patterns that have been detected
|
||||
* at least {@link #CENTER_QUORUM} times each
|
||||
*/
|
||||
private boolean haveMulitplyConfirmedCenters() {
|
||||
int count = 0;
|
||||
int max = possibleCenters.size();
|
||||
|
|
@ -356,6 +412,12 @@ final class FinderPatternFinder {
|
|||
return false;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
|
||||
* those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
|
||||
* size differs from the average among those patterns the least
|
||||
* @throws ReaderException if 3 such finder patterns do not exist
|
||||
*/
|
||||
private FinderPattern[] selectBestPatterns() throws ReaderException {
|
||||
Collections.insertionSort(possibleCenters, new CenterComparator());
|
||||
int size = 0;
|
||||
|
|
@ -393,11 +455,9 @@ final class FinderPatternFinder {
|
|||
}
|
||||
averageModuleSize /= (float) size;
|
||||
|
||||
Collections.insertionSort(
|
||||
possibleCenters,
|
||||
new ClosestToAverageComparator(averageModuleSize));
|
||||
// We don't have java.util.Collections in J2ME
|
||||
Collections.insertionSort(possibleCenters, new ClosestToAverageComparator(averageModuleSize));
|
||||
|
||||
//return confirmedCenters.subList(0, 3).toArray(new FinderPattern[3]);
|
||||
FinderPattern[] result = new FinderPattern[3];
|
||||
for (int i = 0; i < 3; i++) {
|
||||
result[i] = (FinderPattern) possibleCenters.elementAt(i);
|
||||
|
|
@ -405,6 +465,15 @@ final class FinderPatternFinder {
|
|||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>Having found three "best" finder patterns we need to decide which is the top-left, top-right,
|
||||
* bottom-left. We assume that the one closest to the other two is the top-left one; this is not
|
||||
* strictly true (imagine extreme perspective distortion) but for the moment is a serviceable assumption.
|
||||
* Lastly we sort top-right from bottom-left by figuring out orientation from vector cross products.</p>
|
||||
*
|
||||
* @param patterns three best {@link FinderPattern}s
|
||||
* @return same {@link FinderPattern}s ordered bottom-left, top-left, top-right
|
||||
*/
|
||||
private static FinderPattern[] orderBestPatterns(FinderPattern[] patterns) {
|
||||
|
||||
// Find distances between pattern centers
|
||||
|
|
@ -415,10 +484,11 @@ final class FinderPatternFinder {
|
|||
FinderPattern topLeft;
|
||||
FinderPattern topRight;
|
||||
FinderPattern bottomLeft;
|
||||
// Assume one closest to other two is top left
|
||||
// Assume one closest to other two is top left;
|
||||
// topRight and bottomLeft will just be guesses below at first
|
||||
if (bcDistance >= abDistance && bcDistance >= acDistance) {
|
||||
topLeft = patterns[0];
|
||||
topRight = patterns[1]; // These two are guesses at the moment
|
||||
topRight = patterns[1];
|
||||
bottomLeft = patterns[2];
|
||||
} else if (acDistance >= bcDistance && acDistance >= abDistance) {
|
||||
topLeft = patterns[1];
|
||||
|
|
@ -443,18 +513,27 @@ final class FinderPatternFinder {
|
|||
return new FinderPattern[]{bottomLeft, topLeft, topRight};
|
||||
}
|
||||
|
||||
/**
|
||||
* @return distance between two points
|
||||
*/
|
||||
static float distance(ResultPoint pattern1, ResultPoint pattern2) {
|
||||
float xDiff = pattern1.getX() - pattern2.getX();
|
||||
float yDiff = pattern1.getY() - pattern2.getY();
|
||||
return (float) Math.sqrt((double) (xDiff * xDiff + yDiff * yDiff));
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>Orders by {@link FinderPattern#getCount()}, descending.</p>
|
||||
*/
|
||||
private static class CenterComparator implements Comparator {
|
||||
public int compare(Object center1, Object center2) {
|
||||
return ((FinderPattern) center2).getCount() - ((FinderPattern) center1).getCount();
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>Orders by variance from average module size, ascending.</p>
|
||||
*/
|
||||
private static class ClosestToAverageComparator implements Comparator {
|
||||
private float averageModuleSize;
|
||||
|
||||
|
|
|
|||
|
|
@ -17,6 +17,9 @@
|
|||
package com.google.zxing.qrcode.detector;
|
||||
|
||||
/**
|
||||
* <p>Encapsulates information about finder patterns in an image, including the location of
|
||||
* the three finder patterns, and their estimated module size.</p>
|
||||
*
|
||||
* @author srowen@google.com (Sean Owen)
|
||||
*/
|
||||
final class FinderPatternInfo {
|
||||
|
|
|
|||
Loading…
Reference in a new issue