- Qt 5.5
- Qt Widgets
- Plug & Paint Extra Filters Example
- extrafiltersplugin.cpp Example File
- Qt 5.5.1 Reference Documentation

# extrafiltersplugin.cpp Example File

tools/plugandpaintplugins/extrafilters/extrafiltersplugin.cpp

    /****************************************************************************
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    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
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    #include <QtWidgets>

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

    #include "extrafiltersplugin.h"

    QStringList ExtraFiltersPlugin::filters() const
    {
        return QStringList() << tr("Flip Horizontally") << tr("Flip Vertically")
                             << tr("Smudge...") << tr("Threshold...");
    }

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

        if (filter == tr("Flip Horizontally")) {
            for (int y = 0; y < original.height(); ++y) {
                for (int x = 0; x < original.width(); ++x) {
                    int pixel = original.pixel(original.width() - x - 1, y);
                    result.setPixel(x, y, pixel);
                }
            }
        } else if (filter == tr("Flip Vertically")) {
            for (int y = 0; y < original.height(); ++y) {
                for (int x = 0; x < original.width(); ++x) {
                    int pixel = original.pixel(x, original.height() - y - 1);
                    result.setPixel(x, y, pixel);
                }
            }
        } else if (filter == tr("Smudge...")) {
            bool ok;
            int numIters = QInputDialog::getInt(parent, tr("Smudge Filter"),
                                        tr("Enter number of iterations:"),
                                        5, 1, 20, 1, &ok);
            if (ok) {
                for (int i = 0; i < numIters; ++i) {
                    for (int y = 1; y < original.height() - 1; ++y) {
                        for (int x = 1; x < original.width() - 1; ++x) {
                            int p1 = original.pixel(x, y);
                            int p2 = original.pixel(x, y + 1);
                            int p3 = original.pixel(x, y - 1);
                            int p4 = original.pixel(x + 1, y);
                            int p5 = original.pixel(x - 1, y);

                            int red = (qRed(p1) + qRed(p2) + qRed(p3) + qRed(p4)
                                       + qRed(p5)) / 5;
                            int green = (qGreen(p1) + qGreen(p2) + qGreen(p3)
                                         + qGreen(p4) + qGreen(p5)) / 5;
                            int blue = (qBlue(p1) + qBlue(p2) + qBlue(p3)
                                        + qBlue(p4) + qBlue(p5)) / 5;
                            int alpha = (qAlpha(p1) + qAlpha(p2) + qAlpha(p3)
                                         + qAlpha(p4) + qAlpha(p5)) / 5;

                            result.setPixel(x, y, qRgba(red, green, blue, alpha));
                        }
                    }
                }
            }
        } else if (filter == tr("Threshold...")) {
            bool ok;
            int threshold = QInputDialog::getInt(parent, tr("Threshold Filter"),
                                                     tr("Enter threshold:"),
                                                     10, 1, 256, 1, &ok);
            if (ok) {
                int factor = 256 / threshold;
                for (int y = 0; y < original.height(); ++y) {
                    for (int x = 0; x < original.width(); ++x) {
                        int pixel = original.pixel(x, y);
                        result.setPixel(x, y, qRgba(qRed(pixel) / factor * factor,
                                                    qGreen(pixel) / factor * factor,
                                                    qBlue(pixel) / factor * factor,
                                                    qAlpha(pixel)));
                    }
                }
            }
        }
        return result;
    }