/*
- * 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.BlackPointEstimationMethod;
-import com.google.zxing.MonochromeBitmapSource;
-import com.google.zxing.common.BitArray;
-import com.google.zxing.common.BlackPointEstimator;
+import com.google.zxing.common.BaseMonochromeBitmapSource;
import javax.microedition.lcdui.Image;
*
* @author Sean Owen (srowen@google.com), Daniel Switkin (dswitkin@google.com)
*/
-public final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
+public final class LCDUIImageMonochromeBitmapSource extends BaseMonochromeBitmapSource {
- private final int[] rgbPixels;
- private final int width;
+ private final Image image;
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;
+ private final int width;
+ // For why this isn't final, see below
+ private int[] rgbRow;
+ private final int[] pixelHolder;
+ private int cachedRow;
public LCDUIImageMonochromeBitmapSource(Image image) {
- width = image.getWidth();
+ this.image = image;
height = image.getHeight();
- rgbPixels = new int[width * height];
- image.getRGB(rgbPixels, 0, width, 0, 0, width, height);
- blackPoint = 0x7F;
- lastMethod = null;
- lastArgument = 0;
- }
-
- public boolean isBlack(int x, int y) {
- return computeRGBLuminance(rgbPixels[x + y * width]) < blackPoint;
- }
-
- public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) {
- if (row == null) {
- row = new BitArray(getWidth);
- } else {
- row.clear();
- }
- for (int i = 0, offset = y * width + startX; i < getWidth; i++, offset++) {
- if (computeRGBLuminance(rgbPixels[offset]) < blackPoint) {
- row.set(i);
- }
- }
- return row;
+ width = image.getWidth();
+ rgbRow = new int[width];
+ pixelHolder = new int[1];
+ cachedRow = -1;
}
public int getHeight() {
return width;
}
- public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
- if (!method.equals(lastMethod) || argument != lastArgument) {
- int[] histogram = new int[LUMINANCE_BUCKETS];
- float biasTowardsWhite = 1.0f;
- if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
- int minDimension = width < height ? width : height;
- for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
- histogram[computeRGBLuminance(rgbPixels[offset]) >> LUMINANCE_SHIFT]++;
- }
- } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
- if (argument < 0 || argument >= height) {
- throw new IllegalArgumentException("Row is not within the image: " + argument);
- }
- biasTowardsWhite = 2.0f;
- int offset = argument * width;
- for (int x = 0; x < width; x++) {
- histogram[computeRGBLuminance(rgbPixels[offset + x]) >> LUMINANCE_SHIFT]++;
- }
- } else {
- throw new IllegalArgumentException("Unknown method: " + method);
- }
- blackPoint = BlackPointEstimator.estimate(histogram, biasTowardsWhite) << LUMINANCE_SHIFT;
- lastMethod = method;
- lastArgument = argument;
- }
- }
-
- public BlackPointEstimationMethod getLastEstimationMethod() {
- return lastMethod;
- }
+ public int getLuminance(int x, int y) {
- public MonochromeBitmapSource rotateCounterClockwise() {
- throw new IllegalStateException("Rotate not supported");
- }
+ // Below, why the check for rgbRow being the right size? it should never change size
+ // or need to be reallocated. But bizarrely we have seen a but on Sun's WTK, and on
+ // some phones, where the array becomes zero-sized somehow. So we keep making sure the
+ // array is OK.
+ int pixel;
+ if (cachedRow == y && rgbRow.length == width) {
+ pixel = rgbRow[x];
+ } else {
+ image.getRGB(pixelHolder, 0, width, x, y, 1, 1);
+ pixel = pixelHolder[0];
+ }
- public boolean isRotateSupported() {
- return false;
+ // 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;
}
- /**
- * 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;
+ public void cacheRowForLuminance(int y) {
+ if (y != cachedRow) {
+ // See explanation above
+ if (rgbRow.length != width) {
+ rgbRow = new int[width];
+ }
+ image.getRGB(rgbRow, 0, width, 0, y, width, 1);
+ cachedRow = y;
+ }
}
}
\ No newline at end of file