/*

 * 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

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 * 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 "TextStyle.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);

    TextStyle style;

    if (disableRoundingHacks)

        style.disableRoundingHacks();

    return renderer.floatWidth(run, style);

}

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