Qt 5.8 | Qt Quick | C++ Extensions: Image Provider Example | imageprovider.cpp Example File

Qt 5.8.0 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:
      **
      ** "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.
      **   * Redistributions in binary form must reproduce the above copyright
      **     notice, this list of conditions and the following disclaimer in
      **     the documentation and/or other materials provided with the
      **     distribution.
      **   * Neither the name of The Qt Company Ltd nor the names of its
      **     contributors may be used to endorse or promote products derived
      **     from this software without specific prior written permission.
      **
      **
      ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
      ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #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 QQmlExtensionInterface_iid)
      public:
          void registerTypes(const char *uri)
          {
              Q_UNUSED(uri);
          }

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

      };

      #include "imageprovider.moc"