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/*
* Copyright (C) 2005, 2006, 2007 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "StringTruncator.h"
#include "Font.h"
#include "TextBreakIterator.h"
#include "TextRun.h"
#include <wtf/Assertions.h>
#include <wtf/Vector.h>
#include <wtf/unicode/CharacterNames.h>
namespace WebCore {
#define STRING_BUFFER_SIZE 2048
typedef unsigned TruncationFunction(const String&, unsigned length, unsigned keepCount, UChar* buffer);
static inline int textBreakAtOrPreceding(TextBreakIterator* it, int offset)
{
if (isTextBreak(it, offset))
return offset;
int result = textBreakPreceding(it, offset);
return result == TextBreakDone ? 0 : result;
}
static inline int boundedTextBreakFollowing(TextBreakIterator* it, int offset, int length)
{
int result = textBreakFollowing(it, offset);
return result == TextBreakDone ? length : result;
}
static unsigned centerTruncateToBuffer(const String& string, unsigned length, unsigned keepCount, UChar* buffer)
{
ASSERT(keepCount < length);
ASSERT(keepCount < STRING_BUFFER_SIZE);
unsigned omitStart = (keepCount + 1) / 2;
TextBreakIterator* it = characterBreakIterator(string.characters(), length);
unsigned omitEnd = boundedTextBreakFollowing(it, omitStart + (length - keepCount) - 1, length);
omitStart = textBreakAtOrPreceding(it, omitStart);
unsigned truncatedLength = omitStart + 1 + (length - omitEnd);
ASSERT(truncatedLength <= length);
memcpy(buffer, string.characters(), sizeof(UChar) * omitStart);
buffer[omitStart] = horizontalEllipsis;
memcpy(&buffer[omitStart + 1], &string.characters()[omitEnd], sizeof(UChar) * (length - omitEnd));
return truncatedLength;
}
static unsigned rightTruncateToBuffer(const String& string, unsigned length, unsigned keepCount, UChar* buffer)
{
ASSERT(keepCount < length);
ASSERT(keepCount < STRING_BUFFER_SIZE);
TextBreakIterator* it = characterBreakIterator(string.characters(), length);
unsigned keepLength = textBreakAtOrPreceding(it, keepCount);
unsigned truncatedLength = keepLength + 1;
memcpy(buffer, string.characters(), sizeof(UChar) * keepLength);
buffer[keepLength] = horizontalEllipsis;
return truncatedLength;
}
static float stringWidth(const Font& renderer, const UChar* characters, unsigned length)
{
TextRun run(characters, length);
return renderer.width(run);
}
static String truncateString(const String& string, float maxWidth, const Font& font, TruncationFunction truncateToBuffer)
{
if (string.isEmpty())
return string;
ASSERT(maxWidth >= 0);
float currentEllipsisWidth = stringWidth(font, &horizontalEllipsis, 1);
UChar stringBuffer[STRING_BUFFER_SIZE];
unsigned truncatedLength;
unsigned keepCount;
unsigned length = string.length();
if (length > STRING_BUFFER_SIZE) {
keepCount = STRING_BUFFER_SIZE - 1; // need 1 character for the ellipsis
truncatedLength = centerTruncateToBuffer(string, length, keepCount, stringBuffer);
} else {
keepCount = length;
memcpy(stringBuffer, string.characters(), sizeof(UChar) * length);
truncatedLength = length;
}
float width = stringWidth(font, stringBuffer, truncatedLength);
if (width <= maxWidth)
return string;
unsigned keepCountForLargestKnownToFit = 0;
float widthForLargestKnownToFit = currentEllipsisWidth;
unsigned keepCountForSmallestKnownToNotFit = keepCount;
float widthForSmallestKnownToNotFit = width;
if (currentEllipsisWidth >= maxWidth) {
keepCountForLargestKnownToFit = 1;
keepCountForSmallestKnownToNotFit = 2;
}
while (keepCountForLargestKnownToFit + 1 < keepCountForSmallestKnownToNotFit) {
ASSERT(widthForLargestKnownToFit <= maxWidth);
ASSERT(widthForSmallestKnownToNotFit > maxWidth);
float ratio = (keepCountForSmallestKnownToNotFit - keepCountForLargestKnownToFit)
/ (widthForSmallestKnownToNotFit - widthForLargestKnownToFit);
keepCount = static_cast<unsigned>(maxWidth * ratio);
if (keepCount <= keepCountForLargestKnownToFit) {
keepCount = keepCountForLargestKnownToFit + 1;
} else if (keepCount >= keepCountForSmallestKnownToNotFit) {
keepCount = keepCountForSmallestKnownToNotFit - 1;
}
ASSERT(keepCount < length);
ASSERT(keepCount > 0);
ASSERT(keepCount < keepCountForSmallestKnownToNotFit);
ASSERT(keepCount > keepCountForLargestKnownToFit);
truncatedLength = truncateToBuffer(string, length, keepCount, stringBuffer);
width = stringWidth(font, stringBuffer, truncatedLength);
if (width <= maxWidth) {
keepCountForLargestKnownToFit = keepCount;
widthForLargestKnownToFit = width;
} else {
keepCountForSmallestKnownToNotFit = keepCount;
widthForSmallestKnownToNotFit = width;
}
}
if (keepCountForLargestKnownToFit == 0) {
keepCountForLargestKnownToFit = 1;
}
if (keepCount != keepCountForLargestKnownToFit) {
keepCount = keepCountForLargestKnownToFit;
truncatedLength = truncateToBuffer(string, length, keepCount, stringBuffer);
}
return String(stringBuffer, truncatedLength);
}
String StringTruncator::centerTruncate(const String& string, float maxWidth, const Font& font)
{
return truncateString(string, maxWidth, font, centerTruncateToBuffer);
}
String StringTruncator::rightTruncate(const String& string, float maxWidth, const Font& font)
{
return truncateString(string, maxWidth, font, rightTruncateToBuffer);
}
float StringTruncator::width(const String& string, const Font& font)
{
return stringWidth(font, string.characters(), string.length());
}
} // namespace WebCore
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