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Text traversal at various granularities.
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1. Implementing text content navigation at various granularities.
   For views that have content description but no text the
   content description is the traversed at character and word
   granularities. For views that inherit from TextView the
   supported granularities are character, word, line, and page.

bug:5932640

Conflicts:

	core/java/android/view/View.java

Conflicts:

	core/java/android/view/View.java

Change-Id: I66d1e16ce9ac5d6b49f036b17c087b2a7075e4c0
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@sganov
sganov committed May 8, 2012
1 parent 2551e5a commit 6d17a93
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Showing 7 changed files with 861 additions and 13 deletions.
2 changes: 2 additions & 0 deletions api/current.txt
View file
Expand Up @@ -25090,6 +25090,7 @@ package android.view.accessibility {
method public void appendRecord(android.view.accessibility.AccessibilityRecord);
method public int describeContents();
method public static java.lang.String eventTypeToString(int);
method public int getAction();
method public long getEventTime();
method public int getEventType();
method public int getMovementGranularity();
Expand All @@ -25100,6 +25101,7 @@ package android.view.accessibility {
method public static android.view.accessibility.AccessibilityEvent obtain(int);
method public static android.view.accessibility.AccessibilityEvent obtain(android.view.accessibility.AccessibilityEvent);
method public static android.view.accessibility.AccessibilityEvent obtain();
method public void setAction(int);
method public void setEventTime(long);
method public void setEventType(int);
method public void setMovementGranularity(int);
Expand Down
352 changes: 352 additions & 0 deletions core/java/android/view/AccessibilityIterators.java
View file
@@ -0,0 +1,352 @@
/*
* Copyright (C) 2012 The Android Open Source Project
*
* 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 android.view;

import android.content.ComponentCallbacks;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.content.res.Configuration;

import java.text.BreakIterator;
import java.util.Locale;

/**
* This class contains the implementation of text segment iterators
* for accessibility support.
*
* Note: Such iterators are needed in the view package since we want
* to be able to iterator over content description of any view.
*
* @hide
*/
public final class AccessibilityIterators {

/**
* @hide
*/
public static interface TextSegmentIterator {
public int[] following(int current);
public int[] preceding(int current);
}

/**
* @hide
*/
public static abstract class AbstractTextSegmentIterator implements TextSegmentIterator {
protected static final int DONE = -1;

protected String mText;

private final int[] mSegment = new int[2];

public void initialize(String text) {
mText = text;
}

protected int[] getRange(int start, int end) {
if (start < 0 || end < 0 || start == end) {
return null;
}
mSegment[0] = start;
mSegment[1] = end;
return mSegment;
}
}

static class CharacterTextSegmentIterator extends AbstractTextSegmentIterator
implements ComponentCallbacks {
private static CharacterTextSegmentIterator sInstance;

private final Context mAppContext;

protected BreakIterator mImpl;

public static CharacterTextSegmentIterator getInstance(Context context) {
if (sInstance == null) {
sInstance = new CharacterTextSegmentIterator(context);
}
return sInstance;
}

private CharacterTextSegmentIterator(Context context) {
mAppContext = context.getApplicationContext();
Locale locale = mAppContext.getResources().getConfiguration().locale;
onLocaleChanged(locale);
ViewRootImpl.addConfigCallback(this);
}

@Override
public void initialize(String text) {
super.initialize(text);
mImpl.setText(text);
}

@Override
public int[] following(int offset) {
final int textLegth = mText.length();
if (textLegth <= 0) {
return null;
}
if (offset >= textLegth) {
return null;
}
int start = -1;
if (offset < 0) {
offset = 0;
if (mImpl.isBoundary(offset)) {
start = offset;
}
}
if (start < 0) {
start = mImpl.following(offset);
}
if (start < 0) {
return null;
}
final int end = mImpl.following(start);
return getRange(start, end);
}

@Override
public int[] preceding(int offset) {
final int textLegth = mText.length();
if (textLegth <= 0) {
return null;
}
if (offset <= 0) {
return null;
}
int end = -1;
if (offset > mText.length()) {
offset = mText.length();
if (mImpl.isBoundary(offset)) {
end = offset;
}
}
if (end < 0) {
end = mImpl.preceding(offset);
}
if (end < 0) {
return null;
}
final int start = mImpl.preceding(end);
return getRange(start, end);
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
Configuration oldConfig = mAppContext.getResources().getConfiguration();
final int changed = oldConfig.diff(newConfig);
if ((changed & ActivityInfo.CONFIG_LOCALE) != 0) {
Locale locale = newConfig.locale;
onLocaleChanged(locale);
}
}

@Override
public void onLowMemory() {
/* ignore */
}

protected void onLocaleChanged(Locale locale) {
mImpl = BreakIterator.getCharacterInstance(locale);
}
}

static class WordTextSegmentIterator extends CharacterTextSegmentIterator {
private static WordTextSegmentIterator sInstance;

public static WordTextSegmentIterator getInstance(Context context) {
if (sInstance == null) {
sInstance = new WordTextSegmentIterator(context);
}
return sInstance;
}

private WordTextSegmentIterator(Context context) {
super(context);
}

@Override
protected void onLocaleChanged(Locale locale) {
mImpl = BreakIterator.getWordInstance(locale);
}

@Override
public int[] following(int offset) {
final int textLegth = mText.length();
if (textLegth <= 0) {
return null;
}
if (offset >= mText.length()) {
return null;
}
int start = -1;
if (offset < 0) {
offset = 0;
if (mImpl.isBoundary(offset) && isLetterOrDigit(offset)) {
start = offset;
}
}
if (start < 0) {
while ((offset = mImpl.following(offset)) != DONE) {
if (isLetterOrDigit(offset)) {
start = offset;
break;
}
}
}
if (start < 0) {
return null;
}
final int end = mImpl.following(start);
return getRange(start, end);
}

@Override
public int[] preceding(int offset) {
final int textLegth = mText.length();
if (textLegth <= 0) {
return null;
}
if (offset <= 0) {
return null;
}
int end = -1;
if (offset > mText.length()) {
offset = mText.length();
if (mImpl.isBoundary(offset) && offset > 0 && isLetterOrDigit(offset - 1)) {
end = offset;
}
}
if (end < 0) {
while ((offset = mImpl.preceding(offset)) != DONE) {
if (offset > 0 && isLetterOrDigit(offset - 1)) {
end = offset;
break;
}
}
}
if (end < 0) {
return null;
}
final int start = mImpl.preceding(end);
return getRange(start, end);
}

private boolean isLetterOrDigit(int index) {
if (index >= 0 && index < mText.length()) {
final int codePoint = mText.codePointAt(index);
return Character.isLetterOrDigit(codePoint);
}
return false;
}
}

static class ParagraphTextSegmentIterator extends AbstractTextSegmentIterator {
private static ParagraphTextSegmentIterator sInstance;

public static ParagraphTextSegmentIterator getInstance() {
if (sInstance == null) {
sInstance = new ParagraphTextSegmentIterator();
}
return sInstance;
}

@Override
public int[] following(int offset) {
final int textLength = mText.length();
if (textLength <= 0) {
return null;
}
if (offset >= textLength) {
return null;
}
int start = -1;
if (offset < 0) {
start = 0;
} else {
for (int i = offset + 1; i < textLength; i++) {
if (mText.charAt(i) == '\n') {
start = i;
break;
}
}
}
while (start < textLength && mText.charAt(start) == '\n') {
start++;
}
if (start < 0) {
return null;
}
int end = start;
for (int i = end + 1; i < textLength; i++) {
end = i;
if (mText.charAt(i) == '\n') {
break;
}
}
while (end < textLength && mText.charAt(end) == '\n') {
end++;
}
return getRange(start, end);
}

@Override
public int[] preceding(int offset) {
final int textLength = mText.length();
if (textLength <= 0) {
return null;
}
if (offset <= 0) {
return null;
}
int end = -1;
if (offset > mText.length()) {
end = mText.length();
} else {
if (offset > 0 && mText.charAt(offset - 1) == '\n') {
offset--;
}
for (int i = offset - 1; i >= 0; i--) {
if (i > 0 && mText.charAt(i - 1) == '\n') {
end = i;
break;
}
}
}
if (end <= 0) {
return null;
}
int start = end;
while (start > 0 && mText.charAt(start - 1) == '\n') {
start--;
}
if (start == 0 && mText.charAt(start) == '\n') {
return null;
}
for (int i = start - 1; i >= 0; i--) {
start = i;
if (start > 0 && mText.charAt(i - 1) == '\n') {
break;
}
}
start = Math.max(0, start);
return getRange(start, end);
}
}
}

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