File: kfontutils.cpp

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/*********************************************************************************
 *                                                                               *
 *   Copyright (C) 2005, 2009 by Albert Astals Cid <aacid@kde.org>               *
 *                                                                               *
 * This library is free software; you can redistribute it and/or                 *
 * modify it under the terms of the GNU Lesser General Public                    *
 * License as published by the Free Software Foundation; either                  *
 * version 2.1 of the License, or (at your option) version 3, or any             *
 * later version accepted by the membership of KDE e.V. (or its                  *
 * successor approved by the membership of KDE e.V.), which shall                *
 * act as a proxy defined in Section 6 of version 3 of the license.              *
 *                                                                               *
 * This library is distributed in the hope that it will be useful,               *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of                *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU             *
 * Lesser General Public License for more details.                               *
 *                                                                               *
 * You should have received a copy of the GNU Lesser General Public              *
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>. *
 *                                                                               *
 *********************************************************************************/

#include "kfontutils.h"
#include "kfourinline_debug.h"

#include <limits>

#include <QGraphicsTextItem>
#include <QPainter>

qreal KFontUtils::adaptFontSize(QGraphicsTextItem* string, qreal width, qreal height, qreal maxFontSize, qreal minFontSize, qreal precision)
{
    qreal size = maxFontSize;
    QRectF boundingRect;
    // Guard for avoiding possible infinite loop
    qreal lowerBound = 0;
    qreal higherBound = std::numeric_limits<double>::max();
    int count = 0;

    // Loop until found a point size that makes the text fit in the rectangle but
    // don't have more than precision pixels of unused space in any axys.
    while (count < 20) {
        QFont f = string->font();
        f.setPointSizeF(size);
        string->setFont(f);
        string->setTextWidth(width);
        boundingRect = string->boundingRect();
        // Error painting the text, return -1
        if (boundingRect.width() == 0 || boundingRect.height() == 0) {
            return -1;
        }
        // Text doesn't fit in rectangle or has too much unused space, adjust size
        else if (boundingRect.height() > height || boundingRect.height() < height - precision) {

            if (boundingRect.width() > width || boundingRect.height() > height)
              higherBound = qMin(higherBound, size);
            else
              lowerBound = qMax(lowerBound, size);

            if (lowerBound > 0 && higherBound < std::numeric_limits<double>::max()) {
              size = (lowerBound + higherBound) / 2;
            }
            else {
              size = (height / boundingRect.height()) * size;
            }

            count ++;
        }
        // Text fits correctly
        else {
            break;
        }
    }

    // Assure to return a value between minimum and maximum values.
    if (size < minFontSize)
      return minFontSize;
    else if (size > maxFontSize)
      return maxFontSize;
    else
      return size;
}

qreal KFontUtils::adaptFontSize(QGraphicsTextItem* text, const QSizeF &availableSize, qreal maxFontSize, qreal minFontSize, qreal precision)
{
    return adaptFontSize(text, availableSize.width(), availableSize.height(), maxFontSize, minFontSize, precision);
}