/*
- * Copyright (C) 2008 Google Inc.
+ * Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
*/
public abstract class BaseMonochromeBitmapSource implements MonochromeBitmapSource {
- 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;
- public BaseMonochromeBitmapSource() {
+ private final int height;
+ private final int width;
+ private int blackPoint;
+ private BlackPointEstimationMethod lastMethod;
+ private int lastArgument;
+ private int[] luminances;
+
+ protected BaseMonochromeBitmapSource(int width, int height) {
+ this.height = height;
+ this.width = width;
blackPoint = 0x7F;
lastMethod = null;
lastArgument = 0;
}
+ private void initLuminances() {
+ if (luminances == null) {
+ int width = getWidth();
+ int height = getHeight();
+ int max = width > height ? width : height;
+ luminances = new int[max];
+ }
+ }
+
public boolean isBlack(int x, int y) {
return getLuminance(x, y) < blackPoint;
}
row.clear();
}
+ // Reuse the same int array each time
+ initLuminances();
+ luminances = getLuminanceRow(y, luminances);
+
// If the current decoder calculated the blackPoint based on one row, assume we're trying to
// decode a 1D barcode, and apply some sharpening.
- // TODO: We may want to add a fifth parameter to request the amount of shapening to be done.
- cacheRowForLuminance(y);
- if (lastMethod == BlackPointEstimationMethod.ROW_SAMPLING) {
- int left = getLuminance(startX, y);
- int center = getLuminance(startX + 1, y);
+ if (lastMethod.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
+ int left = luminances[startX];
+ int center = luminances[startX + 1];
for (int x = 1; x < getWidth - 1; x++) {
- int right = getLuminance(startX + x + 1, y);
+ int right = luminances[startX + x + 1];
// Simple -1 4 -1 box filter with a weight of 2
int luminance = ((center << 2) - left - right) >> 1;
if (luminance < blackPoint) {
}
} else {
for (int x = 0; x < getWidth; x++) {
- if (getLuminance(startX + x, y) < blackPoint) {
+ if (luminances[startX + x] < blackPoint) {
row.set(x);
}
}
return row;
}
- public abstract int getHeight();
- public abstract int getWidth();
- public abstract int getLuminance(int x, int y);
- public abstract void cacheRowForLuminance(int y);
+ public BitArray getBlackColumn(int x, BitArray column, int startY, int getHeight) {
+ if (column == null || column.getSize() < getHeight) {
+ column = new BitArray(getHeight);
+ } else {
+ column.clear();
+ }
+
+ // Reuse the same int array each time
+ initLuminances();
+ luminances = getLuminanceColumn(x, luminances);
+
+ // We don't handle "row sampling" specially here
+ for (int y = 0; y < getHeight; y++) {
+ if (luminances[startY + y] < blackPoint) {
+ column.set(y);
+ }
+ }
+ return column;
+ }
public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) throws ReaderException {
if (!method.equals(lastMethod) || argument != lastArgument) {
if (argument < 0 || argument >= height) {
throw new IllegalArgumentException("Row is not within the image: " + argument);
}
- cacheRowForLuminance(argument);
+ initLuminances();
+ luminances = getLuminanceRow(argument, luminances);
for (int x = 0; x < width; x++) {
- int luminance = getLuminance(x, argument);
- histogram[luminance >> LUMINANCE_SHIFT]++;
+ histogram[luminances[x] >> LUMINANCE_SHIFT]++;
}
} else {
throw new IllegalArgumentException("Unknown method: " + method);
}
public MonochromeBitmapSource rotateCounterClockwise() {
- throw new IllegalStateException("Rotate not supported");
+ throw new IllegalArgumentException("Rotate not supported");
}
public boolean isRotateSupported() {
return false;
}
+ public final int getHeight() {
+ return height;
+ }
+
+ public final int getWidth() {
+ return width;
+ }
+
+ // These methods below should not need to exist because they are defined in the interface that
+ // this abstract class implements. However this seems to cause problems on some Nokias.
+ // So we write these redundant declarations.
+
+ /**
+ * Retrieves the luminance at the pixel x,y in the bitmap. This method is only used for estimating
+ * the black point and implementing getBlackRow() - it is not meant for decoding, hence it is not
+ * part of MonochromeBitmapSource itself, and is protected.
+ *
+ * @param x The x coordinate in the image.
+ * @param y The y coordinate in the image.
+ * @return The luminance value between 0 and 255.
+ */
+ protected abstract int getLuminance(int x, int y);
+
+ /**
+ * This is the main mechanism for retrieving luminance data. It is dramatically more efficient
+ * than repeatedly calling getLuminance(). As above, this is not meant for decoders.
+ *
+ * @param y The row to fetch
+ * @param row The array to write luminance values into. It is <b>strongly</b> suggested that you
+ * allocate this yourself, making sure row.length >= getWidth(), and reuse the same
+ * array on subsequent calls for performance. If you pass null, you will be flogged,
+ * but then I will take pity on you and allocate a sufficient array internally.
+ * @return The array containing the luminance data. This is the same as row if it was usable.
+ */
+ protected abstract int[] getLuminanceRow(int y, int[] row);
+
+ /**
+ * The same as getLuminanceRow(), but for columns.
+ *
+ * @param x The column to fetch
+ * @param column The array to write luminance values into. See above.
+ * @return The array containing the luminance data.
+ */
+ protected abstract int[] getLuminanceColumn(int x, int[] column);
}
projects / zxing.git / blobdiff