Qt 4.8: imageprovider.cpp Example File (declarative/cppextensions/imageprovider/imageprovider.cpp)

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# imageprovider.cpp Example File

declarative/cppextensions/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:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
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     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
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     **     contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
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     #include <qdeclarativeextensionplugin.h>

     #include <qdeclarativeengine.h>
     #include <qdeclarative.h>
     #include <qdeclarativeitem.h>
     #include <qdeclarativeimageprovider.h>
     #include <qdeclarativeview.h>
     #include <QImage>
     #include <QPainter>

     class ColorImageProvider : public QDeclarativeImageProvider
     {
     public:
         ColorImageProvider()
             : QDeclarativeImageProvider(QDeclarativeImageProvider::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 QDeclarativeExtensionPlugin
     {
         Q_OBJECT
     public:
         void registerTypes(const char *uri)
         {
             Q_UNUSED(uri);
         }

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

     };

     #include "imageprovider.moc"

     Q_EXPORT_PLUGIN(ImageProviderExtensionPlugin);