fbitem.cpp Example File

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  ** This file is part of the examples of the Qt Toolkit.
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  #include "fbitem.h"
  #include <QtGui/QOpenGLFramebufferObject>
  #include <QtGui/QOpenGLContext>
  #include <QtGui/QOpenGLFunctions>
  #include <QtCore/QDebug>

  #if QT_CONFIG(opengl)
  class FbRenderer : public QQuickFramebufferObject::Renderer
  {
  public:
      FbRenderer() : c(0), dir(1) { }

      // The lifetime of the FBO and this class depends on how QQuickWidget
      // manages the scenegraph and context when it comes to showing and hiding
      // the widget. The actual behavior is proven by the debug prints.
      ~FbRenderer() {
          qDebug("FbRenderer destroyed");
      }

      void render() {
          QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
          f->glClearColor(c, 0, 0, 1);
          f->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
          c += 0.01f * dir;
          if (c >= 1.0f || c <= 0.0f)
              dir *= -1;
          update();
      }

      QOpenGLFramebufferObject *createFramebufferObject(const QSize &size) {
          qDebug() << "Creating FBO" << size;
          QOpenGLFramebufferObjectFormat format;
          format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
          return new QOpenGLFramebufferObject(size, format);
      }

  private:
      float c;
      int dir;
  };
  #endif

  QQuickFramebufferObject::Renderer *FbItem::createRenderer() const
  {
  #if QT_CONFIG(opengl)
      return new FbRenderer;
  #else
      return nullptr;
  #endif
  }