Hey Nuno,
done a lot of QQuickRenderControl tricks lately. But I'm using it on
QSGRendererInterface::Software.
I'm not sure if it helps, but check out:
https://stackoverflow.com/questions/17146747/capture-qml-drawing-buffer-without-displaying/67187802#67187802
God speed,
Frank
On 29.06.21 17:27, Nuno Santos wrote:
> Hi,
>
> I’m trying to make a offscreen renderer for a quick scene and then display
> it’s output in the main and visible QQuickWindow scene.
>
> The reason I’m trying to achieve this is because I need to intercept the
> frames to be able to send them to other programs or encode as a video file.
>
> I’ve based myself on the rendercontrol example and I have a working offscreen
> renderer. Now, what I’m trying to do is to paint the result of the offscreen
> renderer into the main QQuickWindow.
>
> What I’m doing is creating a new QQuickItem that paints a texture. When I
> declare this item in qml, I register it on the render control. Render control
> has it’s own render timing. Whenever render control paints, I tell the
> registered quick item to paint with the fbo texture.
>
> The problem is that the only thing that is painted is black. I’m pretty sure
> the quick item is paint texture correctly because it works with images:
>
> // render method
>
> …
>
> if(_renderView)
> {
> _renderView->setImage(_fbo->toImage()); // this works
> _renderView->setTexture(_quickWindow->createTextureFromId(_fbo->texture(),_size));
> // this doesn’t work - only black is painted
> }
>
> …
>
> I wonder if I’m stumbling on synchronisation issues. Maybe when its time for
> the main window to paint again, that texture is not valid anymore.
>
> Performance is a key factor in this architecture. I need the fastest solution
> possible and it doesn’t seem that creating a QImage from a texture and then
> convert it to QSGTexture is the most performant solution possible.
>
> Has anyone been here before?
>
> Any advise on how to overcome this problem?
>
> Thanks!
>
> Best regards,
>
> Nuno
>
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