com.google.zxing.Binarizer Maven / Gradle / Ivy
/*
* Copyright 2009 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;
import com.google.zxing.common.BitArray;
import com.google.zxing.common.BitMatrix;
/**
* This class hierarchy provides a set of methods to convert luminance data to 1 bit data.
* It allows the algorithm to vary polymorphically, for example allowing a very expensive
* thresholding technique for servers and a fast one for mobile. It also permits the implementation
* to vary, e.g. a JNI version for Android and a Java fallback version for other platforms.
*
* @author [email protected] (Daniel Switkin)
*/
public abstract class Binarizer {
private final LuminanceSource source;
protected Binarizer(LuminanceSource source) {
this.source = source;
}
public final LuminanceSource getLuminanceSource() {
return source;
}
/**
* Converts one row of luminance data to 1 bit data. May actually do the conversion, or return
* cached data. Callers should assume this method is expensive and call it as seldom as possible.
* This method is intended for decoding 1D barcodes and may choose to apply sharpening.
* For callers which only examine one row of pixels at a time, the same BitArray should be reused
* and passed in with each call for performance. However it is legal to keep more than one row
* at a time if needed.
*
* @param y The row to fetch, which must be in [0, bitmap height)
* @param row An optional preallocated array. If null or too small, it will be ignored.
* If used, the Binarizer will call BitArray.clear(). Always use the returned object.
* @return The array of bits for this row (true means black).
* @throws NotFoundException if row can't be binarized
*/
public abstract BitArray getBlackRow(int y, BitArray row) throws NotFoundException;
/**
* Converts a 2D array of luminance data to 1 bit data. As above, assume this method is expensive
* and do not call it repeatedly. This method is intended for decoding 2D barcodes and may or
* may not apply sharpening. Therefore, a row from this matrix may not be identical to one
* fetched using getBlackRow(), so don't mix and match between them.
*
* @return The 2D array of bits for the image (true means black).
* @throws NotFoundException if image can't be binarized to make a matrix
*/
public abstract BitMatrix getBlackMatrix() throws NotFoundException;
/**
* Creates a new object with the same type as this Binarizer implementation, but with pristine
* state. This is needed because Binarizer implementations may be stateful, e.g. keeping a cache
* of 1 bit data. See Effective Java for why we can't use Java's clone() method.
*
* @param source The LuminanceSource this Binarizer will operate on.
* @return A new concrete Binarizer implementation object.
*/
public abstract Binarizer createBinarizer(LuminanceSource source);
public final int getWidth() {
return source.getWidth();
}
public final int getHeight() {
return source.getHeight();
}
}