If the 'compute' slot does not take exactly one QString, one int and one double in the specified order, the call will fail. Warning: this method will not test the validity of the arguments: object must be an instance of the class of the QMetaObject of which this QMetaMethod has been constructed with. The arguments must have the same type as the. An overview of Qt’s signals and slots inter-object communication mechanism. Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks. If I’m about to modify a slot function I might take an extra minute to look around since most IDEs can’t tell syntactically where it’s used in a SLOT macro. In this case you have to search for it textually.) Thanks to C11 lambdas and Qt’s ongoing evolution, these short slots can be replaced by a more succinct syntax. QuikTrip, one of the nation’s premier convenience and gasoline marketers, announces the launch of its new Carryout X-Large Pizza – a fresh, made-to-order pizza featuring the same quality ingredients as the by the slice pizza QuikTrip fans have grown to love.
C++ code should provide a class which contains the to-be-called function(as a slot), then register an object of this class to a QWebChannel object, and set the web channel object to the web page object in the QWebEngineView
, and invoking of the function from js would be:
Note that the “const” before the parameter can not be omitted, otherwise, you will get the following error:
Could not convert argument QJsonValue(string, “sd”) to target type .
Qt Signal Slot Call Order
Although data can be passed as parameters of function, it would be more convenient if we can pass data by setting an attribute of an object like:
We expect after the code is executed, “somedata” will be stored in a member variable of the exposed object (webobj) in C++. This is done by delaring a qt property in C++ class:
We can make things even simpler by adding the NOTIFY parameter when declaring the someattribute property.
Qt Slot Call Ordering
Now, if you call webobj->setProperty(“someattribute”,”hello”) somewhere in C++, the signal “someattributeChanged” is automatically emitted and our web page gets updated.
It assumes the jsfun is already defined on your web page, otherwise, you have to define it in the string parameter. The return value is asynchronously passed to the lambda expression as the parameter v.
Now, back to the question raised at the beginning of the post: How to get the value of an html element in C++? It can be done as follows: Casino avenue charles de gaulle paul green.
It uses jQuery functions so make sure jQuery lib is running on your web page.