zxing-js/library

/*
 * 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.
 */

/*namespace com.google.zxing {*/

import LuminanceSource from './LuminanceSource';
import BitArray from './common/BitArray';
import BitMatrix from './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 dswitkin@google.com (Daniel Switkin)
 */
abstract class Binarizer {

    protected constructor(private source: LuminanceSource) { }

    public getLuminanceSource(): LuminanceSource {
        return this.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 getBlackRow(y: number/*iny*/, row: BitArray): BitArray; /*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 getBlackMatrix(): BitMatrix; /*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 createBinarizer(source: LuminanceSource): Binarizer;

    public getWidth(): number /*int*/ {
        return this.source.getWidth();
    }

    public getHeight(): number /*int*/ {
        return this.source.getHeight();
    }
}

export default Binarizer;