The BidiUtils.java Java example source code
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/*
* (C) Copyright IBM Corp. 1999-2000 - All Rights Reserved
*
* The original version of this source code and documentation is
* copyrighted and owned by IBM. These materials are provided
* under terms of a License Agreement between IBM and Sun.
* This technology is protected by multiple US and International
* patents. This notice and attribution to IBM may not be removed.
*/
package sun.font;
import java.text.Bidi;
public final class BidiUtils {
/**
* Return the level of each character into the levels array starting at start.
* This is a convenience method for clients who prefer to use an explicit levels
* array instead of iterating over the runs.
*
* @param levels the array to receive the character levels
* @param start the starting offset into the the array
* @throws IndexOutOfBoundsException if <code>start is less than 0 or
* <code>start + getLength() is greater than levels.length.
*/
public static void getLevels(Bidi bidi, byte[] levels, int start) {
int limit = start + bidi.getLength();
if (start < 0 || limit > levels.length) {
throw new IndexOutOfBoundsException("levels.length = " + levels.length +
" start: " + start + " limit: " + limit);
}
int runCount = bidi.getRunCount();
int p = start;
for (int i = 0; i < runCount; ++i) {
int rlimit = start + bidi.getRunLimit(i);
byte rlevel = (byte)bidi.getRunLevel(i);
while (p < rlimit) {
levels[p++] = rlevel;
}
}
}
/**
* Return an array containing the resolved bidi level of each character, in logical order.
* @return an array containing the level of each character, in logical order.
*/
public static byte[] getLevels(Bidi bidi) {
byte[] levels = new byte[bidi.getLength()];
getLevels(bidi, levels, 0);
return levels;
}
static final char NUMLEVELS = 62;
/**
* Given level data, compute a a visual to logical mapping.
* The leftmost (or topmost) character is at visual index zero. The
* logical index of the character is derived from the visual index
* by the expression <code>li = map[vi];.
* @param levels the levels array
* @return the mapping array from visual to logical
*/
public static int[] createVisualToLogicalMap(byte[] levels) {
int len = levels.length;
int[] mapping = new int[len];
byte lowestOddLevel = (byte)(NUMLEVELS + 1);
byte highestLevel = 0;
// initialize mapping and levels
for (int i = 0; i < len; i++) {
mapping[i] = i;
byte level = levels[i];
if (level > highestLevel) {
highestLevel = level;
}
if ((level & 0x01) != 0 && level < lowestOddLevel) {
lowestOddLevel = level;
}
}
while (highestLevel >= lowestOddLevel) {
int i = 0;
for (;;) {
while (i < len && levels[i] < highestLevel) {
i++;
}
int begin = i++;
if (begin == levels.length) {
break; // no more runs at this level
}
while (i < len && levels[i] >= highestLevel) {
i++;
}
int end = i - 1;
while (begin < end) {
int temp = mapping[begin];
mapping[begin] = mapping[end];
mapping[end] = temp;
++begin;
--end;
}
}
--highestLevel;
}
return mapping;
}
/**
* Return the inverse position map. The source array must map one-to-one (each value
* is distinct and the values run from zero to the length of the array minus one).
* For example, if <code>values[i] = j, then inverse[j] = i.
* @param values the source ordering array
* @return the inverse array
*/
public static int[] createInverseMap(int[] values) {
if (values == null) {
return null;
}
int[] result = new int[values.length];
for (int i = 0; i < values.length; i++) {
result[values[i]] = i;
}
return result;
}
/**
* Return an array containing contiguous values from 0 to length
* having the same ordering as the source array. If this would be
* a canonical ltr ordering, return null. The data in values[] is NOT
* required to be a permutation, but elements in values are required
* to be distinct.
* @param values an array containing the discontiguous values
* @return the contiguous values
*/
public static int[] createContiguousOrder(int[] values) {
if (values != null) {
return computeContiguousOrder(values, 0, values.length);
}
return null;
}
/**
* Compute a contiguous order for the range start, limit.
*/
private static int[] computeContiguousOrder(int[] values, int start,
int limit) {
int[] result = new int[limit-start];
for (int i=0; i < result.length; i++) {
result[i] = i + start;
}
// now we'll sort result[], with the following comparison:
// result[i] lessthan result[j] iff values[result[i]] < values[result[j]]
// selection sort for now; use more elaborate sorts if desired
for (int i=0; i < result.length-1; i++) {
int minIndex = i;
int currentValue = values[result[minIndex]];
for (int j=i; j < result.length; j++) {
if (values[result[j]] < currentValue) {
minIndex = j;
currentValue = values[result[minIndex]];
}
}
int temp = result[i];
result[i] = result[minIndex];
result[minIndex] = temp;
}
// shift result by start:
if (start != 0) {
for (int i=0; i < result.length; i++) {
result[i] -= start;
}
}
// next, check for canonical order:
int k;
for (k=0; k < result.length; k++) {
if (result[k] != k) {
break;
}
}
if (k == result.length) {
return null;
}
// now return inverse of result:
return createInverseMap(result);
}
/**
* Return an array containing the data in the values array from start up to limit,
* normalized to fall within the range from 0 up to limit - start.
* If this would be a canonical ltr ordering, return null.
* NOTE: This method assumes that values[] is a logical to visual map
* generated from levels[].
* @param values the source mapping
* @param levels the levels corresponding to the values
* @param start the starting offset in the values and levels arrays
* @param limit the limiting offset in the values and levels arrays
* @return the normlized map
*/
public static int[] createNormalizedMap(int[] values, byte[] levels,
int start, int limit) {
if (values != null) {
if (start != 0 || limit != values.length) {
// levels optimization
boolean copyRange, canonical;
byte primaryLevel;
if (levels == null) {
primaryLevel = (byte) 0x0;
copyRange = true;
canonical = true;
}
else {
if (levels[start] == levels[limit-1]) {
primaryLevel = levels[start];
canonical = (primaryLevel & (byte)0x1) == 0;
// scan for levels below primary
int i;
for (i=start; i < limit; i++) {
if (levels[i] < primaryLevel) {
break;
}
if (canonical) {
canonical = levels[i] == primaryLevel;
}
}
copyRange = (i == limit);
}
else {
copyRange = false;
// these don't matter; but the compiler cares:
primaryLevel = (byte) 0x0;
canonical = false;
}
}
if (copyRange) {
if (canonical) {
return null;
}
int[] result = new int[limit-start];
int baseValue;
if ((primaryLevel & (byte)0x1) != 0) {
baseValue = values[limit-1];
} else {
baseValue = values[start];
}
if (baseValue == 0) {
System.arraycopy(values, start, result, 0, limit-start);
}
else {
for (int j=0; j < result.length; j++) {
result[j] = values[j+start] - baseValue;
}
}
return result;
}
else {
return computeContiguousOrder(values, start, limit);
}
}
else {
return values;
}
}
return null;
}
/**
* Reorder the objects in the array into visual order based on their levels.
* This is a utility function to use when you have a collection of objects
* representing runs of text in logical order, each run containing text
* at a single level. The elements in the objects array will be reordered
* into visual order assuming each run of text has the level provided
* by the corresponding element in the levels array.
* @param levels an array representing the bidi level of each object
* @param objects the array of objects to be reordered into visual order
*/
public static void reorderVisually(byte[] levels, Object[] objects) {
int len = levels.length;
byte lowestOddLevel = (byte)(NUMLEVELS + 1);
byte highestLevel = 0;
// initialize mapping and levels
for (int i = 0; i < len; i++) {
byte level = levels[i];
if (level > highestLevel) {
highestLevel = level;
}
if ((level & 0x01) != 0 && level < lowestOddLevel) {
lowestOddLevel = level;
}
}
while (highestLevel >= lowestOddLevel) {
int i = 0;
for (;;) {
while (i < len && levels[i] < highestLevel) {
i++;
}
int begin = i++;
if (begin == levels.length) {
break; // no more runs at this level
}
while (i < len && levels[i] >= highestLevel) {
i++;
}
int end = i - 1;
while (begin < end) {
Object temp = objects[begin];
objects[begin] = objects[end];
objects[end] = temp;
++begin;
--end;
}
}
--highestLevel;
}
}
}
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