[PyQt] Implementation of the QQuickFramebufferObject

[Phil Thompson]

On 21 Sep 2015, at 11:44 am, Rostyslav Lyulinetskyy <info at rostik.de> wrote:
> 
> On 18.09.2015 19:03, Phil Thompson wrote:
>> On 15 Sep 2015, at 12:14 pm, Rostyslav Lyulinetskyy <info at rostik.de> wrote:
>>> Hi,
>>> 
>>> I am trying to port my c++ code to python and I am integrating a custom OpenGL rendering with Qt Quick via QQuickFramebufferObject (as described here: https://blog.qt.io/blog/2015/05/11/integrating-custom-opengl-rendering-with-qt-quick-via-qquickframebufferobject/)
>>> Everything works well in c++, but for various reasons I need to port this to python and it doesn't seem to work. The virtual function createRenderer() in the QQuickFramebufferObject must be overridden so one can return a new renderer, but for some reason this function is not even called when using PyQt.
>>> 
>>> Is it even possible to override this virtual function from python? Am I missing something?
>>> 
>>> Here is a small example to replicate that the createRenderer() function is not called:
>>> https://gist.github.com/rostikL/7876e4c47fc8dd8ce02f
>> Tonight's snapshot will make sure createRenderer() is called. However there may well be issues with the ownership of the returned renderer. Please test and let me know.
>> 
>> Phil
> Hi,
> 
> Thanks for the implementation. I have tested it and createRenderer() function is being called now. I have now extended the example (https://gist.github.com/rostikL/7876e4c47fc8dd8ce02f) to get a new Renderer object which inherits from the QQuickFramebufferObject.Renderer class and the application crashes with "Segmentation fault" as error message.
> 
> The same thing happens in c++ when the following 3 functions are not implemented in the new Renderer:
> - createFrameBufferObject(self, size)
> - render () (is called when something changes)
> - synchronize(self, item) (called as a result of QQuickFramebufferObject::update())
> 
> So I assume these methods are not properly implemented in PyQt and can not be overridden at the moment?

No, as suspected I hadn't got the ownership issues correct. Try tonight's snapshot.

Phil