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# basictoolsplugin.cpp Example File
tools/plugandpaintplugins/basictools/basictoolsplugin.cpp

        /****************************************************************************
        **
        ** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
        ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
    ** General Public Licensing requirements will be met:
    ** http://www.trolltech.com/products/qt/opensource.html
    **
    ** If you are unsure which license is appropriate for your use, please
    ** review the following information:
    ** http://www.trolltech.com/products/qt/licensing.html or contact the
    ** sales department at sales@trolltech.com.
        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        **
        ****************************************************************************/

        #include <QtGui>

        #include <math.h>
        #include <stdlib.h>

        #include "basictoolsplugin.h"

        const float Pi = 3.14159f;

        QStringList BasicToolsPlugin::brushes() const
        {
            return QStringList() << tr("Pencil") << tr("Air Brush")
                                 << tr("Random Letters");
        }

        QRect BasicToolsPlugin::mousePress(const QString &brush, QPainter &painter,
                                           const QPoint &pos)
        {
            return mouseMove(brush, painter, pos, pos);
        }

        QRect BasicToolsPlugin::mouseMove(const QString &brush, QPainter &painter,
                                          const QPoint &oldPos, const QPoint &newPos)
        {
            painter.save();

            int rad = painter.pen().width() / 2;
            QRect boundingRect = QRect(oldPos, newPos).normalized()
                                                      .adjusted(-rad, -rad, +rad, +rad);
            QColor color = painter.pen().color();
            int thickness = painter.pen().width();
            QColor transparentColor(color.red(), color.green(), color.blue(), 0);

            if (brush == tr("Pencil")) {
                painter.drawLine(oldPos, newPos);
            } else if (brush == tr("Air Brush")) {
                int numSteps = 2 + (newPos - oldPos).manhattanLength() / 2;

                painter.setBrush(QBrush(color, Qt::Dense6Pattern));
                painter.setPen(Qt::NoPen);

                for (int i = 0; i < numSteps; ++i) {
                    int x = oldPos.x() + i * (newPos.x() - oldPos.x()) / (numSteps - 1);
                    int y = oldPos.y() + i * (newPos.y() - oldPos.y()) / (numSteps - 1);

                    painter.drawEllipse(x - (thickness / 2), y - (thickness / 2),
                                        thickness, thickness);
                }
            } else if (brush == tr("Random Letters")) {
                QChar ch('A' + (rand() % 26));

                QFont biggerFont = painter.font();
                biggerFont.setBold(true);
                biggerFont.setPointSize(biggerFont.pointSize() + thickness);
                painter.setFont(biggerFont);

                painter.drawText(newPos, QString(ch));

                QFontMetrics metrics(painter.font());
                boundingRect = metrics.boundingRect(ch);
                boundingRect.translate(newPos);
                boundingRect.adjust(-10, -10, +10, +10);
            }
            painter.restore();
            return boundingRect;
        }

        QRect BasicToolsPlugin::mouseRelease(const QString & /* brush */,
                                             QPainter & /* painter */,
                                             const QPoint & /* pos */)
        {
            return QRect(0, 0, 0, 0);
        }

        QStringList BasicToolsPlugin::shapes() const
        {
            return QStringList() << tr("Circle") << tr("Star") << tr("Text...");
        }

        QPainterPath BasicToolsPlugin::generateShape(const QString &shape,
                                                     QWidget *parent)
        {
            QPainterPath path;

            if (shape == tr("Circle")) {
                path.addEllipse(0, 0, 50, 50);
            } else if (shape == tr("Star")) {
                path.moveTo(90, 50);
                for (int i = 1; i < 5; ++i) {
                    path.lineTo(50 + 40 * cos(0.8 * i * Pi),
                                50 + 40 * sin(0.8 * i * Pi));
                }
                path.closeSubpath();
            } else if (shape == tr("Text...")) {
                QString text = QInputDialog::getText(parent, tr("Text Shape"),
                                                     tr("Enter text:"),
                                                     QLineEdit::Normal, tr("Qt"));
                if (!text.isEmpty()) {
                    QFont timesFont("Times", 50);
                    timesFont.setStyleStrategy(QFont::ForceOutline);
                    path.addText(0, 0, timesFont, text);
                }
            }

            return path;
        }

        QStringList BasicToolsPlugin::filters() const
        {
            return QStringList() << tr("Invert Pixels") << tr("Swap RGB")
                                 << tr("Grayscale");
        }

        QImage BasicToolsPlugin::filterImage(const QString &filter, const QImage &image,
                                             QWidget * /* parent */)
        {
            QImage result = image.convertToFormat(QImage::Format_RGB32);

            if (filter == tr("Invert Pixels")) {
                result.invertPixels();
            } else if (filter == tr("Swap RGB")) {
                result = result.rgbSwapped();
            } else if (filter == tr("Grayscale")) {
                for (int y = 0; y < result.height(); ++y) {
                    for (int x = 0; x < result.width(); ++x) {
                        int pixel = result.pixel(x, y);
                        int gray = qGray(pixel);
                        int alpha = qAlpha(pixel);
                        result.setPixel(x, y, qRgba(gray, gray, gray, alpha));
                    }
                }
            }
            return result;
        }

        Q_EXPORT_PLUGIN(BasicToolsPlugin)