2 * Copyright 2007 ZXing authors
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 package com.google.zxing;
19 import com.google.zxing.common.BitArray;
22 * <p>Encapsulates a generic black-and-white bitmap -- a collection of pixels in two dimensions.
23 * This unifies many possible representations, like AWT's <code>BufferedImage</code>.</p>
26 * @author dswitkin@google.com (Daniel Switkin)
28 public interface MonochromeBitmapSource {
31 * @param x horizontal offset, from left, of the pixel
32 * @param y vertical offset, from top, of the pixel
33 * @return true iff the pixel at (x,y) is black
35 boolean isBlack(int x, int y);
38 * <p>Returns an entire row of black/white pixels as an array of bits, where "true" means "black".
39 * This is a sort of "bulk get" operation intended to enable efficient access in
40 * certain situations.</p>
42 * @param y vertical offset, from top, of the row of pixels
43 * @param row if not null, {@link BitArray} to write pixels into. If null, a new {@link BitArray}
44 * is allocated and returned.
45 * @param startX horizontal offset, from left, from which to start getting pixels
46 * @param getWidth number of pixels to get from the row
47 * @return {@link BitArray} representing the (subset of the) row of pixels. If row parameter
48 * was not null, it is returned.
50 BitArray getBlackRow(int y, BitArray row, int startX, int getWidth);
53 * Entirely analogous to {@link #getBlackRow(int, BitArray, int, int)} but gets a column.
55 BitArray getBlackColumn(int x, BitArray column, int startY, int getHeight);
57 BitArray getBlackDiagonal(int x, int y, int dx, int dy, BitArray diagonal, int size);
60 * @return height of underlying image
65 * @return width of underlying image
70 * <p>Estimates black point according to the given method, which is optionally parameterized by
71 * a single int argument. For {@link BlackPointEstimationMethod#ROW_SAMPLING}, this
72 * specifies the row to sample.</p>
74 * <p>The estimated value will be used in subsequent computations that rely on an estimated black
77 * @param method black point estimation method
78 * @param argument method-specific argument
80 void estimateBlackPoint(BlackPointEstimationMethod method, int argument) throws ReaderException;
83 * @return {@link BlackPointEstimationMethod} representing last sampling method used
85 BlackPointEstimationMethod getLastEstimationMethod();
88 * <p>Optional operation which returns an implementation based on the same underlying
89 * image, but which behaves as if the underlying image had been rotated 90 degrees
90 * counterclockwise. This is useful in the context of 1D barcodes and the
91 * {@link DecodeHintType#TRY_HARDER} decode hint, and is only intended to be
92 * used in non-resource-constrained environments. Hence, implementations
93 * of this class which are only used in resource-constrained mobile environments
94 * don't have a need to implement this.</p>
96 * @throws IllegalArgumentException if not supported
98 MonochromeBitmapSource rotateCounterClockwise();
101 * @return true iff rotation is supported
102 * @see #rotateCounterClockwise()
104 boolean isRotateSupported();
107 * Retrieves the luminance at the pixel x,y in the bitmap. This method is only used for estimating
108 * the black point and implementing getBlackRow() - it is not meant for decoding, hence it is not
109 * part of MonochromeBitmapSource itself, and is protected.
111 * @param x The x coordinate in the image.
112 * @param y The y coordinate in the image.
113 * @return The luminance value between 0 and 255.
115 int getLuminance(int x, int y);
118 * This is the main mechanism for retrieving luminance data. It is dramatically more efficient
119 * than repeatedly calling getLuminance(). As above, this is not meant for decoders.
121 * @param y The row to fetch
122 * @param row The array to write luminance values into. It is <b>strongly</b> suggested that you
123 * allocate this yourself, making sure row.length >= getWidth(), and reuse the same
124 * array on subsequent calls for performance. If you pass null, you will be flogged,
125 * but then I will take pity on you and allocate a sufficient array internally.
126 * @return The array containing the luminance data. This is the same as row if it was usable.
128 int[] getLuminanceRow(int y, int[] row);
131 * The same as getLuminanceRow(), but for columns.
133 * @param x The column to fetch
134 * @param column The array to write luminance values into. See above.
135 * @return The array containing the luminance data.
137 int[] getLuminanceColumn(int x, int[] column);