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88 lines
3.5 KiB
Java
88 lines
3.5 KiB
Java
/*
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* Copyright 2009 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.zxing;
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import com.google.zxing.common.BitArray;
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import com.google.zxing.common.BitMatrix;
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/**
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* This class hierarchy provides a set of methods to convert luminance data to 1 bit data.
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* It allows the algorithm to vary polymorphically, for example allowing a very expensive
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* thresholding technique for servers and a fast one for mobile. It also permits the implementation
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* to vary, e.g. a JNI version for Android and a Java fallback version for other platforms.
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*
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* @author dswitkin@google.com (Daniel Switkin)
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*/
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public abstract class Binarizer {
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private final LuminanceSource source;
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protected Binarizer(LuminanceSource source) {
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this.source = source;
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}
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public final LuminanceSource getLuminanceSource() {
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return source;
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}
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/**
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* Converts one row of luminance data to 1 bit data. May actually do the conversion, or return
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* cached data. Callers should assume this method is expensive and call it as seldom as possible.
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* This method is intended for decoding 1D barcodes and may choose to apply sharpening.
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* For callers which only examine one row of pixels at a time, the same BitArray should be reused
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* and passed in with each call for performance. However it is legal to keep more than one row
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* at a time if needed.
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*
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* @param y The row to fetch, which must be in [0, bitmap height)
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* @param row An optional preallocated array. If null or too small, it will be ignored.
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* If used, the Binarizer will call BitArray.clear(). Always use the returned object.
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* @return The array of bits for this row (true means black).
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* @throws NotFoundException if row can't be binarized
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*/
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public abstract BitArray getBlackRow(int y, BitArray row) throws NotFoundException;
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/**
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* Converts a 2D array of luminance data to 1 bit data. As above, assume this method is expensive
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* and do not call it repeatedly. This method is intended for decoding 2D barcodes and may or
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* may not apply sharpening. Therefore, a row from this matrix may not be identical to one
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* fetched using getBlackRow(), so don't mix and match between them.
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*
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* @return The 2D array of bits for the image (true means black).
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* @throws NotFoundException if image can't be binarized to make a matrix
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*/
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public abstract BitMatrix getBlackMatrix() throws NotFoundException;
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/**
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* Creates a new object with the same type as this Binarizer implementation, but with pristine
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* state. This is needed because Binarizer implementations may be stateful, e.g. keeping a cache
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* of 1 bit data. See Effective Java for why we can't use Java's clone() method.
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*
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* @param source The LuminanceSource this Binarizer will operate on.
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* @return A new concrete Binarizer implementation object.
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*/
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public abstract Binarizer createBinarizer(LuminanceSource source);
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public final int getWidth() {
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return source.getWidth();
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}
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public final int getHeight() {
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return source.getHeight();
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}
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}
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