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Diffstat (limited to 'WebCore/platform/graphics/StringTruncator.cpp')
-rw-r--r-- | WebCore/platform/graphics/StringTruncator.cpp | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/WebCore/platform/graphics/StringTruncator.cpp b/WebCore/platform/graphics/StringTruncator.cpp new file mode 100644 index 0000000..0490a9f --- /dev/null +++ b/WebCore/platform/graphics/StringTruncator.cpp @@ -0,0 +1,199 @@ +/* + * 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 "CharacterNames.h" +#include "Font.h" +#include "FontPlatformData.h" +#include "TextBreakIterator.h" +#include <wtf/Assertions.h> +#include <wtf/Vector.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, bool disableRoundingHacks) +{ + TextRun run(characters, length); + if (disableRoundingHacks) + run.disableRoundingHacks(); + return renderer.floatWidth(run); +} + +static String truncateString(const String& string, float maxWidth, const Font& font, TruncationFunction truncateToBuffer, bool disableRoundingHacks) +{ + if (string.isEmpty()) + return string; + + ASSERT(maxWidth >= 0); + + float currentEllipsisWidth = stringWidth(font, &horizontalEllipsis, 1, disableRoundingHacks); + + 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, disableRoundingHacks); + 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, disableRoundingHacks); + 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, bool disableRoundingHacks) +{ + return truncateString(string, maxWidth, font, centerTruncateToBuffer, disableRoundingHacks); +} + +String StringTruncator::rightTruncate(const String& string, float maxWidth, const Font& font, bool disableRoundingHacks) +{ + return truncateString(string, maxWidth, font, rightTruncateToBuffer, disableRoundingHacks); +} + +float StringTruncator::width(const String& string, const Font& font, bool disableRoundingHacks) +{ + return stringWidth(font, string.characters(), string.length(), disableRoundingHacks); +} + +} // namespace WebCore |