fbitem.cpp Example File | Qt Quick 5.12.12

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- fbitem.cpp Example File
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# fbitem.cpp Example File

quickwidgets/quickwidget/fbitem.cpp

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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() { }

         // 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() override {
             qDebug("FbRenderer destroyed");
         }

         void render() override {
             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) override {
             qDebug() << "Creating FBO" << size;
             QOpenGLFramebufferObjectFormat format;
             format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
             return new QOpenGLFramebufferObject(size, format);
         }

     private:
         float c = 0;
         int dir = 1;
     };
     #endif

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