- Qt 5.5
- Qt Quick
- C++ Extensions: Image Provider Example
- imageprovider.cpp Example File
- Qt 5.5.1 Reference Documentation

# imageprovider.cpp Example File

imageprovider/imageprovider.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
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    #include <qqmlextensionplugin.h>

    #include <qqmlengine.h>
    #include <qquickimageprovider.h>
    #include <QImage>
    #include <QPainter>

    class ColorImageProvider : public QQuickImageProvider
    {
    public:
        ColorImageProvider()
            : QQuickImageProvider(QQuickImageProvider::Pixmap)
        {
        }

        QPixmap requestPixmap(const QString &id, QSize *size, const QSize &requestedSize)
        {
            int width = 100;
            int height = 50;

            if (size)
                *size = QSize(width, height);
            QPixmap pixmap(requestedSize.width() > 0 ? requestedSize.width() : width,
                           requestedSize.height() > 0 ? requestedSize.height() : height);
            pixmap.fill(QColor(id).rgba());

            // write the color name
            QPainter painter(&pixmap);
            QFont f = painter.font();
            f.setPixelSize(20);
            painter.setFont(f);
            painter.setPen(Qt::black);
            if (requestedSize.isValid())
                painter.scale(requestedSize.width() / width, requestedSize.height() / height);
            painter.drawText(QRectF(0, 0, width, height), Qt::AlignCenter, id);

            return pixmap;
        }
    };

    class ImageProviderExtensionPlugin : public QQmlExtensionPlugin
    {
        Q_OBJECT
        Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QQmlExtensionInterface")
    public:
        void registerTypes(const char *uri)
        {
            Q_UNUSED(uri);
        }

        void initializeEngine(QQmlEngine *engine, const char *uri)
        {
            Q_UNUSED(uri);
            engine->addImageProvider("colors", new ColorImageProvider);
        }

    };

    #define QQmlExtensionInterface_iid "org.qt-project.Qt.QQmlExtensionInterface"

    #include "imageprovider.moc"