/*
- * Copyright 2007 Google Inc.
+ * Copyright 2007 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
package com.google.zxing.client.j2me;
-import com.google.zxing.MonochromeBitmapSource;
-import com.google.zxing.BlackPointEstimationMethod;
-import com.google.zxing.common.BitArray;
-import com.google.zxing.common.BlackPointEstimator;
+import com.google.zxing.common.BaseMonochromeBitmapSource;
import javax.microedition.lcdui.Image;
/**
* <p>An implementation based on Java ME's {@link Image} representation.</p>
- *
- * @author Sean Owen (srowen@google.com), Daniel Switkin (dswitkin@google.com)
+ *
+ * @author Sean Owen
+ * @author Daniel Switkin (dswitkin@google.com)
*/
-final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
+public final class LCDUIImageMonochromeBitmapSource extends BaseMonochromeBitmapSource {
- private final int[] rgbPixels;
- private final int width;
- private final int height;
- private int blackPoint;
- private BlackPointEstimationMethod lastMethod;
+ private final Image image;
+ private final int[] pixelHolder;
- LCDUIImageMonochromeBitmapSource(final Image image) {
- width = image.getWidth();
- height = image.getHeight();
- rgbPixels = new int[width * height];
- image.getRGB(rgbPixels, 0, width, 0, 0, width, height);
- blackPoint = 0x7F;
+ public LCDUIImageMonochromeBitmapSource(Image image) {
+ super(image.getWidth(), image.getHeight());
+ this.image = image;
+ pixelHolder = new int[1];
}
- public boolean isBlack(int x, int y) {
- return computeRGBLuminance(rgbPixels[x + y * width]) < blackPoint;
+ // This is expensive and should be used very sparingly.
+ protected int getLuminance(int x, int y) {
+ image.getRGB(pixelHolder, 0, getWidth(), x, y, 1, 1);
+ int pixel = pixelHolder[0];
+
+ // Instead of multiplying by 306, 601, 117, we multiply by 256, 512, 256, so that
+ // the multiplies can be implemented as shifts.
+ //
+ // Really, it's:
+ //
+ // return ((((pixel >> 16) & 0xFF) << 8) +
+ // (((pixel >> 8) & 0xFF) << 9) +
+ // (( pixel & 0xFF) << 8)) >> 10;
+ //
+ // That is, we're replacing the coefficients in the original with powers of two,
+ // which can be implemented as shifts, even though changing the coefficients slightly
+ // corrupts the conversion. Not significant for our purposes.
+ return (((pixel & 0x00FF0000) >> 16) +
+ ((pixel & 0x0000FF00) >> 7) +
+ (pixel & 0x000000FF )) >> 2;
}
- public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) {
- if (row == null) {
- row = new BitArray(getWidth);
- } else {
- row.clear();
+ // For efficiency, the RGB data and the luminance data share the same array.
+ protected int[] getLuminanceRow(int y, int[] row) {
+ int width = getWidth();
+ if (row == null || row.length < width) {
+ row = new int[width];
}
- for (int i = 0, offset = y * width + startX; i < getWidth; i++, offset++) {
- if (computeRGBLuminance(rgbPixels[offset]) < blackPoint) {
- row.set(i);
- }
+ image.getRGB(row, 0, width, 0, y, width, 1);
+ for (int x = 0; x < width; x++) {
+ int pixel = row[x];
+ row[x] = (((pixel & 0x00FF0000) >> 16) +
+ ((pixel & 0x0000FF00) >> 7) +
+ (pixel & 0x000000FF )) >> 2;
}
return row;
}
- public int getHeight() {
- return height;
- }
-
- public int getWidth() {
- return width;
- }
-
- public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
- if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
- if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(lastMethod)) {
- int[] luminanceBuckets = new int[32];
- int minDimension = width < height ? width : height;
- for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
- luminanceBuckets[computeRGBLuminance(rgbPixels[offset]) >> 3]++;
- }
- blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
- }
- } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
- // TODO
- } else {
- throw new IllegalArgumentException("Unknown method: " + method);
+ protected int[] getLuminanceColumn(int x, int[] column) {
+ int height = getHeight();
+ if (column == null || column.length < height) {
+ column = new int[height];
}
- lastMethod = method;
- }
-
- public BlackPointEstimationMethod getLastEstimationMethod() {
- return lastMethod;
- }
-
- /**
- * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB,
- * so this implementation computes luminance is a function of a red, green and blue components as
- * follows:
- *
- * <code>Y = 0.299R + 0.587G + 0.114B</code>
- *
- * where R, G, and B are values in [0,1].
- */
- private static int computeRGBLuminance(int pixel) {
- // Coefficients add up to 1024 to make the divide into a fast shift
- return (306 * ((pixel >> 16) & 0xFF) +
- 601 * ((pixel >> 8) & 0xFF) +
- 117 * (pixel & 0xFF)) >> 10;
+ image.getRGB(column, 0, 1, x, 0, 1, height);
+ for (int y = 0; y < height; y++) {
+ int pixel = column[y];
+ column[y] = (((pixel & 0x00FF0000) >> 16) +
+ ((pixel & 0x0000FF00) >> 7) +
+ (pixel & 0x000000FF )) >> 2;
+ }
+ return column;
}
-}
\ No newline at end of file
+}
projects / zxing.git / blobdiff