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One of the undoubted advantages of QML in Qt is that it allows a fairly sharp separation of backend logic from the application interface. That is, we write all the backend in C ++, and in QML we only display the required result.

In doing so, we can also write internal logic purely on QML, minimizing the presence of C ++ code, or vice versa, design the design of some elements in C ++, taking advantage of the OpenGL capabilities. Despite the distinction between QML and C ++ code parts on the backend and frontend applications, we do not have any big restrictions.

Step 1: Create Projects Create a Subdirs Project, then create 2 qt quick sub projects named: Light and LightController Light project: contains an image represent for the light Light controller: has 2 buttons for turn on and turn off the light from the other project Step 2: Create the UIs The Light. QINVOKABLE QString errorString const: QINVOKABLE int exitCode const: QINVOKABLE QProcess::ExitStatus exitStatus const: QINVOKABLE bool getChar (char.c) QINVOKABLE bool isOpen const: QINVOKABLE bool isReadable const: QINVOKABLE bool isSequential const: QINVOKABLE bool isTextModeEnabled const: QINVOKABLE bool. See QINVOKABLE. slot void QCamera:: viewAll Rotates and moves the camera so that it's viewCenter is the center of the scene's bounding volume and the entire scene fits in the view port. Note: Only works if the lens is in perspective projection mode. See also Qt3D.Render::Camera::projectionType. slot void QCamera:: viewEntity (Qt3DCore. I'm just curious, is it more lightweight to mark a method with QINVOKABLE than as a slot? Is it more of a design question to mark a method with QINVOKABLE, for instance a method that calculates and returns a value but is not inteeded to be used with signals.

But sometimes it becomes necessary to transfer some data structure that will carry several fields with information, in the QML part of the code. For example, such a structure.

It's just that this structure can not be passed to QML and the first thing that comes to mind is to make the sendToQml signal, which will send out several arguments. Each argument will be responsible for a specific field structure.

Public Slots: void OnAddPlugin (QString plugin) Add a plugin to the window. Void OnLoadConfig (const QString &path) Callback when load configuration is selected. Void OnSaveConfig Callback when 'save configuration' is selected. Void OnSaveConfigAs (const QString &path) Callback when 'save configuration as' is selected.

This signal will be located in your class, which will send to QML certain information with numbers, messages, etc. The minus of this approach is obvious, since there can be a lot of such fields and it will be foolish to make a signal with a couple of dozens of arguments. This approach will be useful for sending small information, but not for data structures.

There is another option to use QVariantMap. Because it is well-converted into an array of QML, from which you can collect data by key. An example of use is the official Qt documentation.

Thus, the information in QML

And thus this information is added to C ++

But I do not particularly like this approach, since there can be a situation when it is necessary to do certain actions with data that the structure carries in itself, and QVariantMap, of such methods can not have in principle. Yes, and I want a more complete presentation of information than a set of keys and values. If this is some message or data object that is passed within the C ++ code and work happens to it as an integral object, then why should we turn it into a set of key-value pairs that live inside QVariantMap?

That's right, it's not necessary. The matter is that from C ++ it is possible to transfer in QML the pointer on object of class QObject . And given the possibilities of polymorphism , inheritance, etc. You can inherit from the QObject class and pass a pointer to this object in QML as a pointer to the QObject base class. Moreover, without even registering this new class as MetaType in the Qt meta-object system.

What will it give us? We understand that if you inherit from a class and add some methods and fields to the inherited class, you can work with them and call them, but you will need to have a pointer to the object of the corresponding class, that is, if we take pointer to the base class and assign it a pointer to the inherited class, then within the code we can not write a call to the method of the derived class when working with the base class pointer. That is, the following code is not compiled.

And logically, there is no sense to inherit from QObject without registering the class via qmlRegisterType . However, everything is different here, as we are accustomed to. The fact is that if the method is marked as a signal, a slot or Q_INVOKABLE method or some of the fields is marked as Q_PROPERTY , then the meta-object system Qt already knows about this method or field. And the method, for example, can be called through the static method of the QMetaObject class. Due to this, these methods can be called in QML, even if there is a pointer to the base class QObject.

And now let's look at an example of the structure and class that are inherited from QObject, and which will be passed to QML.

Container.h

Здесь мы видим классический вариант объявления полей и методов для кастомного объекта, с которым будет работать в QML . То есть имеются макросы Q_PROPERTY и Q_INVOKABLE , а также имеются сигналы и слоты.

Here we see a classic variant of declaring fields and methods for a custom object, which will work in QML . That is, there are macros Q_PROPERTY and Q_INVOKABLE , and there are signals and slots.

Container.cpp

The contents of the source file should not be called at all.

Factory of objects

For the convenience of creating objects in C ++ code and passing the pointer in QML, I will create a special factory that will be registered in the context of QML, which will quickly create Structures and Containers with information and return a pointer to these objects in QML.

Factory.h

Factory.cpp

You can notice that as a parent, I set up a factory. When working with pointers and passing them from C ++ to QML, there are nuances with pointer ownership. If the object is not exposed to parent, then it can be destroyed by the garbage collector in QML, eventually we can get an invalid pointer in C ++. Read more in this article .

main.cpp

Let's see how the registration of the factory looks in the context of QML. This will allow you to access the factory anywhere in the QML code.

main.qml

After all the preparatory operations have been carried out, we will try to create several structures and containers and refer to their fields and methods to derive information from them.

And we will place structures and containers in the same array. I already said above that QVariantMap and QVariantList are converted in QML into a JavaScript array, which does not care which information is placed in it. Therefore, when we try to go through all the elements of the array and call the methods number, message and getFullInfo() , we will not have any problems. In this case, all these methods will be implicitly called through the QMetaObject::invokeMethod method, and if the method is registered, it will be called. Because in the array objects of two different classes, the main thing here is that the methods should have the same name. This is very much like the behavior of duck typing in Python . Although of course this is not duck typing. This is a feature of the Meta-object system Qt .

The result will be as follows

A singleton class that manages the oAuth 2.0 user agent/refresh flow. More...

#include <core/SFAuthenticationManager.h>

Detailed Description

A singleton class that manages the oAuth 2.0 user agent/refresh flow.

This is a singleton class and its instance can be accessed by by SFAuthenticationManager::instance()

Initialization

Before using this class to start the authentication process, the application code needs to specify the required information to connect to salesforce.com:

• consumer key: set this value in your applicationui class by defining the SFRemoteAccessConsumerKey variable
• redirect url: set this value in your applicationui class by defining the SFRemoteAccessConsumerKey variable
• scopes: optionally set the scopes you want the access token to be associated with. Set its value by calling SFAuthenticationManager::setScopes(QList<QString> newScopes);

Note

The consumer key, redirect url and scopes information is persisted on the device. If you decide to reconfigured these information, the change will take effect only after the app performed a logout or the app is deleted and re-installed. See SFAccountManager for more details

Usage

To use this class, connect to the desired signals and invoke the desired functions

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In order for the SDK to handle the authentication process. It uses a few QML assets to construct the UI needed during authentication They can be found in the assets/salesforce folder

• SFSettings.qml: a screen for user to specify which environment to connect the application to. The application developer is responsible for presenting this screen if a setting screen is required in the application. The SDK will do the necessary clean up tasks and emit a LoginHostChanged signal. The application is responsible for handling this signal (e.g. trigger login again)
• SFOAuthSheet.qml: a sheet that holds the web view for authentication. It is presented and dismissed by SFAuthenticationManager as part of the login process
• SFPasscodeCreation.qml: a sheet that lets user set up device password after authentication. It is presented and dismissed by SFAuthenticationManager
• SFLockScreen.qml: a sheet that locks the screen when the app is inactive for a period of time. It is presented and dismissed by SFAuthenticationManager

See Also

SFAuthenticationManager, SFAbstractApplicationUI See Authenticating Remote Access Application OAuth for more details. This SDK supports the oAuth 2.0 user agent flow and refresh token flow.

Definition at line 91 of file SFAuthenticationManager.h.

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Cancels in progress authentication (stops web view from loading, or aborts refresh token connection) Does not clear existing account data.

Starts the authentication process and emits either the success or failure signal This function will trigger the user-agent flow if the refresh token is not available otherwise the refresh token flow will be triggered.

Cancels any authentication in progress and clears stored account data

This slot is connected to the application's fullscreen signal to automatically display either the login screen or lock screen.

Emitted if user went into settings and changed the login host

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Definition at line 169 of file SFAuthenticationManager.h.