Qt 5.6 | Qt OpenGL | 2D Painting Example | helper.cpp Example File

Qt 5.6.2 Reference Documentation

# helper.cpp Example File

2dpainting/helper.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
      **
      ** This file is part of the examples of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
      ** 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 "helper.h"

      #include <QPainter>
      #include <QPaintEvent>
      #include <QWidget>

      Helper::Helper()
      {
          QLinearGradient gradient(QPointF(50, -20), QPointF(80, 20));
          gradient.setColorAt(0.0, Qt::white);
          gradient.setColorAt(1.0, QColor(0xa6, 0xce, 0x39));

          background = QBrush(QColor(64, 32, 64));
          circleBrush = QBrush(gradient);
          circlePen = QPen(Qt::black);
          circlePen.setWidth(1);
          textPen = QPen(Qt::white);
          textFont.setPixelSize(50);
      }

      void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed)
      {
          painter->fillRect(event->rect(), background);
          painter->translate(100, 100);

          painter->save();
          painter->setBrush(circleBrush);
          painter->setPen(circlePen);
          painter->rotate(elapsed * 0.030);

          qreal r = elapsed / 1000.0;
          int n = 30;
          for (int i = 0; i < n; ++i) {
              painter->rotate(30);
              qreal factor = (i + r) / n;
              qreal radius = 0 + 120.0 * factor;
              qreal circleRadius = 1 + factor * 20;
              painter->drawEllipse(QRectF(radius, -circleRadius,
                                          circleRadius * 2, circleRadius * 2));
          }
          painter->restore();

          painter->setPen(textPen);
          painter->setFont(textFont);
          painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, QStringLiteral("Qt"));
      }