2 * Copyright 2008 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.client.j2se;
19 import com.google.zxing.MonochromeBitmapSource;
20 import com.google.zxing.common.BaseMonochromeBitmapSource;
22 import java.awt.geom.AffineTransform;
23 import java.awt.image.AffineTransformOp;
24 import java.awt.image.BufferedImage;
25 import java.awt.image.BufferedImageOp;
28 * <p>An implementation based upon {@link BufferedImage}. This provides access to the
29 * underlying image as if it were a monochrome image. Behind the scenes, it is evaluating
30 * the luminance of the underlying image by retrieving its pixels' RGB values.</p>
32 * <p>This may also be used to construct a {@link MonochromeBitmapSource}
33 * based on a region of a {@link BufferedImage}; see
34 * {@link #BufferedImageMonochromeBitmapSource(BufferedImage, int, int, int, int)}.</p>
37 * @author Daniel Switkin (dswitkin@google.com)
39 public final class BufferedImageMonochromeBitmapSource extends BaseMonochromeBitmapSource {
41 private final BufferedImage image;
42 private final int left;
43 private final int top;
46 * Creates an instance that uses the entire given image as a source of pixels to decode.
48 * @param image image to decode
50 public BufferedImageMonochromeBitmapSource(BufferedImage image) {
51 this(image, 0, 0, image.getWidth(), image.getHeight());
55 * Creates an instance that uses only a region of the given image as a source of pixels to decode.
57 * @param image image to decode a region of
58 * @param left x coordinate of leftmost pixels to decode
59 * @param top y coordinate of topmost pixels to decode
60 * @param right one more than the x coordinate of rightmost pixels to decode, i.e. we will decode
61 * pixels whose x coordinate is in [left,right)
62 * @param bottom likewise, one more than the y coordinate of the bottommost pixels to decode
64 public BufferedImageMonochromeBitmapSource(BufferedImage image, int left, int top, int right,
66 super(right - left, bottom - top);
68 int sourceHeight = image.getHeight();
69 int sourceWidth = image.getWidth();
70 if (left < 0 || top < 0 || right > sourceWidth || bottom > sourceHeight || right <= left ||
72 throw new IllegalArgumentException("Invalid bounds: (" + top + ',' + left + ") (" + right +
80 * @return underlying {@link BufferedImage} behind this instance. Note that even if this instance
81 * only uses a subset of the full image, the returned value here represents the entire backing
84 public BufferedImage getImage() {
89 public MonochromeBitmapSource rotateCounterClockwise() {
90 if (!isRotateSupported()) {
91 throw new IllegalStateException("Rotate not supported");
93 int sourceWidth = image.getWidth();
94 int sourceHeight = image.getHeight();
96 // 90 degrees counterclockwise:
97 AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
98 BufferedImageOp op = new AffineTransformOp(transform, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);
100 // Note width/height are flipped since we are rotating 90 degrees:
101 BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, image.getType());
102 op.filter(image, rotatedImage);
103 return new BufferedImageMonochromeBitmapSource(rotatedImage,
105 sourceWidth - (left + getWidth()),
111 public boolean isRotateSupported() {
112 // Can't run AffineTransforms on images of unknown format
113 return image.getType() != BufferedImage.TYPE_CUSTOM;
117 * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB,
118 * so this implementation computes luminance is a function of a red, green and blue components as
121 * <code>Y = 0.299R + 0.587G + 0.114B</code>
123 * where R, G, and B are values in [0,1].
126 protected int getLuminance(int x, int y) {
127 int pixel = image.getRGB(left + x, top + y);
128 // Coefficients add up to 1024 to make the divide into a fast shift
129 return (306 * ((pixel >> 16) & 0xFF) +
130 601 * ((pixel >> 8) & 0xFF) +
131 117 * (pixel & 0xFF)) >> 10;
135 protected int[] getLuminanceRow(int y, int[] row) {
136 int width = getWidth();
137 if (row == null || row.length < width) {
138 row = new int[width];
140 image.getRGB(left, top + y, width, 1, row, 0, width);
141 for (int x = 0; x < width; x++) {
143 row[x] = (306 * ((pixel >> 16) & 0xFF) +
144 601 * ((pixel >> 8) & 0xFF) +
145 117 * (pixel & 0xFF)) >> 10;
151 protected int[] getLuminanceColumn(int x, int[] column) {
152 int height = getHeight();
153 if (column == null || column.length < height) {
154 column = new int[height];
156 image.getRGB(left + x, top, 1, height, column, 0, 1);
157 for (int y = 0; y < height; y++) {
158 int pixel = column[y];
159 column[y] = (306 * ((pixel >> 16) & 0xFF) +
160 601 * ((pixel >> 8) & 0xFF) +
161 117 * (pixel & 0xFF)) >> 10;