97 lines
3.0 KiB
Java
97 lines
3.0 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.multi;
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import com.google.zxing.BinaryBitmap;
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import com.google.zxing.ChecksumException;
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import com.google.zxing.FormatException;
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import com.google.zxing.NotFoundException;
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import com.google.zxing.Reader;
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import com.google.zxing.Result;
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import java.util.Hashtable;
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/**
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* This class attempts to decode a barcode from an image, not by scanning the whole image,
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* but by scanning subsets of the image. This is important when there may be multiple barcodes in
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* an image, and detecting a barcode may find parts of multiple barcode and fail to decode
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* (e.g. QR Codes). Instead this scans the four quadrants of the image -- and also the center
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* 'quadrant' to cover the case where a barcode is found in the center.
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*
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* @see GenericMultipleBarcodeReader
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*/
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public final class ByQuadrantReader implements Reader {
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private final Reader delegate;
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public ByQuadrantReader(Reader delegate) {
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this.delegate = delegate;
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}
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public Result decode(BinaryBitmap image)
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throws NotFoundException, ChecksumException, FormatException {
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return decode(image, null);
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}
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public Result decode(BinaryBitmap image, Hashtable hints)
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throws NotFoundException, ChecksumException, FormatException {
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int width = image.getWidth();
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int height = image.getHeight();
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int halfWidth = width / 2;
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int halfHeight = height / 2;
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BinaryBitmap topLeft = image.crop(0, 0, halfWidth, halfHeight);
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try {
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return delegate.decode(topLeft, hints);
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} catch (NotFoundException re) {
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// continue
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}
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BinaryBitmap topRight = image.crop(halfWidth, 0, halfWidth, halfHeight);
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try {
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return delegate.decode(topRight, hints);
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} catch (NotFoundException re) {
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// continue
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}
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BinaryBitmap bottomLeft = image.crop(0, halfHeight, halfWidth, halfHeight);
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try {
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return delegate.decode(bottomLeft, hints);
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} catch (NotFoundException re) {
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// continue
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}
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BinaryBitmap bottomRight = image.crop(halfWidth, halfHeight, halfWidth, halfHeight);
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try {
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return delegate.decode(bottomRight, hints);
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} catch (NotFoundException re) {
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// continue
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}
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int quarterWidth = halfWidth / 2;
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int quarterHeight = halfHeight / 2;
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BinaryBitmap center = image.crop(quarterWidth, quarterHeight, halfWidth, halfHeight);
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return delegate.decode(center, hints);
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}
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public void reset() {
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delegate.reset();
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}
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}
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