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/*
* Copyright (C) 2013 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.
*/
import android.text.Spanned;
import android.text.style.SuggestionSpan;
import java.util.Arrays;
/**
* Represents a range of text, relative to the current cursor position.
*/
public final class TextRange {
private final CharSequence mTextAtCursor;
private final int mWordAtCursorStartIndex;
private final int mWordAtCursorEndIndex;
private final int mCursorIndex;
public final CharSequence mWord;
public int getNumberOfCharsInWordBeforeCursor() {
return mCursorIndex - mWordAtCursorStartIndex;
}
public int getNumberOfCharsInWordAfterCursor() {
return mWordAtCursorEndIndex - mCursorIndex;
}
public int length() {
return mWord.length();
}
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/**
* Gets the suggestion spans that are put squarely on the word, with the exact start
* and end of the span matching the boundaries of the word.
* @return the list of spans.
*/
public SuggestionSpan[] getSuggestionSpansAtWord() {
if (!(mTextAtCursor instanceof Spanned && mWord instanceof Spanned)) {
return new SuggestionSpan[0];
}
final Spanned text = (Spanned)mTextAtCursor;
// Note: it's fine to pass indices negative or greater than the length of the string
// to the #getSpans() method. The reason we need to get from -1 to +1 is that, the
// spans were cut at the cursor position, and #getSpans(start, end) does not return
// spans that end at `start' or begin at `end'. Consider the following case:
// this| is (The | symbolizes the cursor position
// ---- ---
// In this case, the cursor is in position 4, so the 0~7 span has been split into
// a 0~4 part and a 4~7 part.
// If we called #getSpans(0, 4) in this case, we would only get the part from 0 to 4
// of the span, and not the part from 4 to 7, so we would not realize the span actually
// extends from 0 to 7. But if we call #getSpans(-1, 5) we'll get both the 0~4 and
// the 4~7 spans and we can merge them accordingly.
// Any span starting more than 1 char away from the word boundaries in any direction
// does not touch the word, so we don't need to consider it. That's why requesting
// -1 ~ +1 is enough.
// Of course this is only relevant if the cursor is at one end of the word. If it's
// in the middle, the -1 and +1 are not necessary, but they are harmless.
final SuggestionSpan[] spans = text.getSpans(mWordAtCursorStartIndex - 1,
mWordAtCursorEndIndex + 1, SuggestionSpan.class);
int readIndex = 0;
int writeIndex = 0;
for (; readIndex < spans.length; ++readIndex) {
final SuggestionSpan span = spans[readIndex];
// The span may be null, as we null them when we find duplicates. Cf a few lines
// down.
if (null == span) continue;
// Tentative span start and end. This may be modified later if we realize the
// same span is also applied to other parts of the string.
int spanStart = text.getSpanStart(span);
int spanEnd = text.getSpanEnd(span);
for (int i = readIndex + 1; i < spans.length; ++i) {
if (span.equals(spans[i])) {
// We found the same span somewhere else. Read the new extent of this
// span, and adjust our values accordingly.
spanStart = Math.min(spanStart, text.getSpanStart(spans[i]));
spanEnd = Math.max(spanEnd, text.getSpanEnd(spans[i]));
// ...and mark the span as processed.
spans[i] = null;
}
}
if (spanStart == mWordAtCursorStartIndex && spanEnd == mWordAtCursorEndIndex) {
// If the span does not start and stop here, ignore it. It probably extends
// past the start or end of the word, as happens in missing space correction
// or EasyEditSpans put by voice input.
spans[writeIndex++] = spans[readIndex];
}
}
return writeIndex == readIndex ? spans : Arrays.copyOfRange(spans, 0, writeIndex);
}
public TextRange(final CharSequence textAtCursor, final int wordAtCursorStartIndex,
final int wordAtCursorEndIndex, final int cursorIndex, final boolean hasUrlSpans) {
if (wordAtCursorStartIndex < 0 || cursorIndex < wordAtCursorStartIndex
|| cursorIndex > wordAtCursorEndIndex
|| wordAtCursorEndIndex > textAtCursor.length()) {
throw new IndexOutOfBoundsException();
}
mTextAtCursor = textAtCursor;
mWordAtCursorStartIndex = wordAtCursorStartIndex;
mWordAtCursorEndIndex = wordAtCursorEndIndex;
mCursorIndex = cursorIndex;
mWord = mTextAtCursor.subSequence(mWordAtCursorStartIndex, mWordAtCursorEndIndex);
}
}