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Avoid tiny Array.sort; a bottleneck

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This commit is contained in:
Sean Owen 2020-05-13 14:12:34 -05:00
parent 05abe0f7aa
commit f8df5f0ca2
1 changed files with 37 additions and 6 deletions
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43
core/src/main/java/com/google/zxing/qrcode/detector/FinderPatternFinder.java
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@ -624,7 +624,6 @@ public class FinderPatternFinder {
possibleCenters.sort(moduleComparator); possibleCenters.sort(moduleComparator);
double distortion = Double.MAX_VALUE; double distortion = Double.MAX_VALUE;
double[] squares = new double[3];
FinderPattern[] bestPatterns = new FinderPattern[3]; FinderPattern[] bestPatterns = new FinderPattern[3];
for (int i = 0; i < possibleCenters.size() - 2; i++) { for (int i = 0; i < possibleCenters.size() - 2; i++) {
@ -643,17 +642,49 @@ public class FinderPatternFinder {
continue; continue;
} }
squares[0] = squares0; double a = squares0;
squares[1] = squaredDistance(fpj, fpk); double b = squaredDistance(fpj, fpk);
squares[2] = squaredDistance(fpi, fpk); double c = squaredDistance(fpi, fpk);
Arrays.sort(squares);
// sorts ascending - inlined
if (a < b) {
if (b > c) {
if (a < c) {
double temp = b;
b = c;
c = temp;
} else {
double temp = a;
a = c;
c = b;
b = temp;
}
}
} else {
if (b < c) {
if (a < c) {
double temp = a;
a = b;
b = temp;
} else {
double temp = a;
a = b;
b = c;
c = temp;
}
} else {
double temp = a;
a = c;
c = temp;
}
}
// a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle). // a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle).
// Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0, // Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0,
// we need to check both two equal sides separately. // we need to check both two equal sides separately.
// The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity // The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity
// from isosceles right triangle. // from isosceles right triangle.
double d = Math.abs(squares[2] - 2 * squares[1]) + Math.abs(squares[2] - 2 * squares[0]); double d = Math.abs(c - 2 * b) + Math.abs(c - 2 * a);
if (d < distortion) { if (d < distortion) {
distortion = d; distortion = d;
bestPatterns[0] = fpi; bestPatterns[0] = fpi;