FinderPattern.java revision 7e3fa36d69ffee874dd364b8e3d9aa3cab9a273b
/*
* 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.ResultPoint;
/**
* <p>Encapsulates a finder pattern, which are the three square patterns found in
* the corners of QR Codes. It also encapsulates a count of similar finder patterns,
* as a convenience to the finder's bookkeeping.</p>
*
* @author Sean Owen
*/
public final class FinderPattern extends ResultPoint {
private final float estimatedModuleSize;
private final int count;
FinderPattern(float posX, float posY, float estimatedModuleSize) {
this(posX, posY, estimatedModuleSize, 1);
}
private FinderPattern(float posX, float posY, float estimatedModuleSize, int count) {
super(posX, posY);
this.estimatedModuleSize = estimatedModuleSize;
this.count = count;
}
public float getEstimatedModuleSize() {
return estimatedModuleSize;
}
int getCount() {
return count;
}
/*
void incrementCount() {
this.count++;
}
*/
/**
* <p>Determines if this finder pattern "about equals" a finder pattern at the stated
* position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
*/
boolean aboutEquals(float moduleSize, float i, float j) {
if (Math.abs(i - getY()) <= moduleSize && Math.abs(j - getX()) <= moduleSize) {
float moduleSizeDiff = Math.abs(moduleSize - estimatedModuleSize);
return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
}
return false;
}
/**
* Combines this object's current estimate of a finder pattern position and module size
* with a new estimate. It returns a new {@code FinderPattern} containing a weighted average
* based on count.
*/
FinderPattern combineEstimate(float i, float j, float newModuleSize) {
int combinedCount = count + 1;
float combinedX = (count * getX() + j) / combinedCount;
float combinedY = (count * getY() + i) / combinedCount;
float combinedModuleSize = (count * estimatedModuleSize + newModuleSize) / combinedCount;
return new FinderPattern(combinedX, combinedY, combinedModuleSize, combinedCount);
}
}