I am trying to connect a signal and slot in qt c . What I want to achieve is that when the browser finishes rendering the page I want it to emit the signal and receive it in my slot. I initially wrote it for urlChanged() signal and it works fine but when I change it to renderProcessTerminated, it doesnt output the statements in the slot function.

The following is a snippet of the MyClass.h file where the slot is declared:

private slots:
        void onRenderProcessTerminated(QWebEnginePage::RenderProcessTerminationStatus terminationStatus, int exitCode);

The following is a snippet from the constructor of MyClass.cpp file where the signal and slot are connected:

connect(ui->webEngineView, &QWebEngineView::renderProcessTerminated, this, &MyClass::onRenderProcessTerminated);

The following is the slot function onRenderProcessTerminated from MyClass.cpp (cout is a function I created to output messages in the web engine view and works fine):

void MyClass::onRenderProcessTerminated(QWebEnginePage::RenderProcessTerminationStatus terminationStatus, int exitCode) {
    cout("INSIDE RENDER PROCESS TERMINATED");
}

CodePudding user response：

What I want to achieve is that when the browser finishes rendering the page I want it to emit the signal

RenderProcessTerminated doesn't mean "finished rendering the page". It means that the operating system's process that was used for rendering has terminated abnormally. It happens e.g. when the renderer crashes. Qt documentation clearly states:

This signal is emitted when the render process is terminated with a non-zero exit status. terminationStatus is the termination status of the process and exitCode is the status code with which the process terminated.

In English, the verb you'd be looking for is finished instead of terminated. The former implies the latter: when a process is finished, it has terminated. But the reverse is not necessary: a process may well terminate before it's finished with its task, e.g. if it crashes, or is terminated when the parent process exits, etc. But also: the RenderProcess doesn't mean "a task of rendering something". It literally means "the operating system process that performs the rendering". That process normally must stay alive for as long as you have any web views active.

The only signal I can see that approximates what you want is QWebEngineView::loadFinished(bool ok). Try it out.

Ohterwise, for finer notifications, you'll need to inject some javascript into the view, and interact with it. It may be more effort than it's worth.