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[Solved] Rendering QImage on QGLWidget of QML plugin
karlphillip last edited by
I'm trying to write a QML plugin that reads frames from a Video (using a custom widget and NOT QtMultimedia/Phonon), then each frame is converted to a QImage with format RGB888, and then displayed on a QGLWidget. Right now nothing seems to be draw on the screen (the screen stays white).
It's important to state that I already have all of this working without QGLWidget, so I know the issue is setting up and drawing on QGLWidget.
The plugin is being registered with:
so Video is the main class of the plugin. On it's constructor we have:
: QDeclarativeItem(parent), d_ptr(new VideoPrivate(this))
Q_D(Video); QDeclarativeView* view = new QDeclarativeView; view->setViewport(&d->canvas()); // canvas() returns a reference to my custom OpenGL Widget
Before I jump to the canvas object, let me say that I overloaded Video::paint() so it calls canvas.paint() while passing QImage as parameter, I don't know if this is the right way to do it so I would like some advice on this:
@void Video::paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget)
Q_D(Video); // I know for sure at this point "d->image()" is valid, but I'm hiding the code for clarity d->canvas().paint(painter, option, d->image());
The canvas object is declared as GLWidget canvas; and the header of this class is defined as:
@class GLWidget : public QGLWidget
explicit GLWidget(QWidget* parent = NULL);
void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QImage* image);
Seems pretty simple. Now, the implementation of QGLWidget is the following:
: QGLWidget(QGLFormat(QGL::SampleBuffers), parent)
// Should I do something here?
// Maybe setAutoFillBackground(false); ???
@void GLWidget::paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QImage* image)
// I ignore painter because it comes from Video, so I create a new one:
// Perform drawing as Qt::KeepAspectRatio
gl_painter.fillRect(QRectF(QPoint(0, 0), QSize(this->width(), this->height())), Qt::black);
QImage scaled_img = image->scaled(QSize(this->width(), this->height()), _ar, Qt::FastTransformation);
gl_painter.drawImage(qRound(this->width()/2) - qRound(scaled_img.size().width()/2),
qRound(this->height()/2) - qRound(scaled_img.size().height()/2),
What am I missing?
karlphillip last edited by
The answer for this question "is here":http://stackoverflow.com/a/8488275/176769.
koahnig last edited by
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