--- /dev/null
+/*
+ * Copyright (C) 2008 Google Inc.
+ *
+ * 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.
+ */
+
+package com.google.zxing.client.android;
+
+import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.BlackPointEstimationMethod;
+import com.google.zxing.common.BitArray;
+import com.google.zxing.common.BlackPointEstimator;
+
+import android.graphics.Bitmap;
+
+/**
+ * This object implements MonochromeBitmapSource around an Android Bitmap. Rather than capturing an
+ * RGB image and calculating the grey value at each pixel, we ask the camera driver for YUV data and
+ * strip out the luminance channel directly. This should be faster but provides fewer bits, i.e.
+ * fewer grey levels.
+ *
+ * @author dswitkin@google.com (Daniel Switkin)
+ * @author srowen@google.com (Sean Owen)
+ */
+final class YUVMonochromeBitmapSource implements MonochromeBitmapSource {
+
+ private final Bitmap image;
+ private final BitArray[] blackWhitePixels;
+ private final int width;
+ private final int height;
+ private int blackPoint;
+ private BlackPointEstimationMethod lastMethod;
+ private int lastArgument;
+
+ private static final int LUMINANCE_BITS = 5;
+ private static final int LUMINANCE_SHIFT = 8 - LUMINANCE_BITS;
+ private static final int LUMINANCE_BUCKETS = 1 << LUMINANCE_BITS;
+
+ YUVMonochromeBitmapSource(Bitmap image) {
+ width = image.width();
+ height = image.height();
+ this.image = image;
+ blackWhitePixels = new BitArray[height];
+ blackPoint = 0x7F;
+ lastMethod = null;
+ lastArgument = 0;
+ }
+
+ public boolean isBlack(int x, int y) {
+ BitArray blackWhite = blackWhitePixels[y];
+ if (blackWhite == null) {
+ blackWhite = parseBlackWhite(y);
+ }
+ return blackWhite.get(x);
+ }
+
+ public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) {
+ BitArray blackWhite = blackWhitePixels[y];
+ if (blackWhite == null) {
+ blackWhite = parseBlackWhite(y);
+ }
+ if (row == null) {
+ if (startX == 0 && getWidth == width) {
+ return blackWhite;
+ }
+ row = new BitArray(getWidth);
+ } else {
+ row.clear();
+ }
+ for (int i = 0; i < getWidth; i++) {
+ if (blackWhite.get(startX + i)) {
+ row.set(i);
+ }
+ }
+ return row;
+ }
+
+ private BitArray parseBlackWhite(int y) {
+ int width = this.width;
+ int[] pixelRow = new int[width];
+ image.getPixels(pixelRow, 0, width, 0, y, width, 1);
+ BitArray luminanceRow = new BitArray(width);
+ int blackPoint = this.blackPoint;
+ // Calculate 32 bits at a time to more efficiently set the bit array
+ int bits = 0;
+ int bitCount = 0;
+ for (int j = 0; j < width; j++) {
+ bits >>>= 1;
+ // Computation of luminance is inlined here for speed:
+ if (((pixelRow[j] >> 16) & 0xFF) <= blackPoint) {
+ bits |= 0x80000000;
+ }
+ if (++bitCount == 32) {
+ luminanceRow.setBulk(j, bits);
+ bits = 0;
+ bitCount = 0;
+ }
+ }
+ if (bitCount > 0) {
+ luminanceRow.setBulk(width, bits >>> (32 - bitCount));
+ }
+ blackWhitePixels[y] = luminanceRow;
+ return luminanceRow;
+ }
+
+ public int getHeight() {
+ return height;
+ }
+
+ public int getWidth() {
+ return width;
+ }
+
+ public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
+ if (!method.equals(lastMethod) || argument != lastArgument) {
+ for (int i = 0; i < blackWhitePixels.length; i++) {
+ blackWhitePixels[i] = null;
+ }
+ int[] histogram = new int[LUMINANCE_BUCKETS];
+ if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
+ int minDimension = width < height ? width : height;
+ int startI = height == minDimension ? 0 : (height - width) >> 1;
+ int startJ = width == minDimension ? 0 : (width - height) >> 1;
+ for (int n = 0; n < minDimension; n++) {
+ int pixel = image.getPixel(startJ + n, startI + n);
+ // Computation of luminance is inlined here for speed:
+ histogram[((pixel >> 16) & 0xFF) >> LUMINANCE_SHIFT]++;
+ }
+ } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
+ if (argument < 0 || argument >= height) {
+ throw new IllegalArgumentException("Row is not within the image: " + argument);
+ }
+ int[] yuvArray = new int[width];
+ image.getPixels(yuvArray, 0, width, 0, argument, width, 1);
+ for (int x = 0; x < width; x++) {
+ histogram[((yuvArray[x] >> 16) & 0xFF) >> LUMINANCE_SHIFT]++;
+ }
+ } else {
+ throw new IllegalArgumentException("Unknown method: " + method);
+ }
+ blackPoint = BlackPointEstimator.estimate(histogram, 1.0f) << LUMINANCE_SHIFT;
+ lastMethod = method;
+ lastArgument = argument;
+ }
+ }
+
+ public BlackPointEstimationMethod getLastEstimationMethod() {
+ return lastMethod;
+ }
+
+}
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projects / zxing.git / blobdiff