Real-time waveform display of CAN communication data based on QT (serial eight) ==== "Sub function or new class calls ui control"

Foreword

After the data in the main program is transferred to the new class (here is the thread, others are similar), you need to draw in it, so you need to call the controls of the ui interface.I searched for many methods on the Internet, and tried them one by one, but there was no way to achieve it perfectly, either here or there.So I wonder if I used a fake QT myself, why, I don't know, it just can't come out with reference to their method.Discuss with experts and combine the online examples to come up with a solution that can be solved, which is very easy to use, and is consistent with the method above, which is very convenient.

Part 1: Sub-functions or other classes call ui controls

The first step: Create a control in the ui of the main function. The control in qcustomplot is used here. If this part will not be added, you can refer to the method in the previous article. It is very convenient and simple, and the steps are very detailed..An improved widget is used here, now the qcustomplot class.The name is PLOTVSAMP.In fact, it is also possible to directly pull a button. I have tested this, and it works.

Step 2: In the main function, define the function.The first sentence has been introduced above, define a new class in the main function, and this class name is also its newly created class name.It doesn't matter which parent class he is a subclass of.My parent class here is the thread QThread class.How to create a reference to the previous article, written in great detail.

 mythread = new datadeal(this);mythread->SetMainWindow( this );

Step 3: Change the private members in the main function h file to public members, this location should be easy to find.Prepare for the new class to call the UI controls.

public:Ui::MainWindow *ui;

Step 4: In the second step, the function has been set, and there is no function body. Add the function declaration and body to the h file of the new class, and define the pointer of the main window here (not very suitable, just look at it this way, it is calledThere is a little problem, easy to understand), in fact, in the second step, this refers to the pointer in the mainwindow, which is put here as a formal parameter. This is the entry of the mainwindow, which is defined as pwinmain.At the same time, assign this pointer to m_pwinmain, so that the pointer of the main window is given to the pointer in the new class.

public:void SetMainWindow( MainWindow* pWinMain ){m_pWinMain = pWinMain;}

Step 5: The pointer to the main program of the new class already exists, and the position where the pointer is defined is the same as that of the main program.

private:MainWindow* m_pWinMain;

Step 6: Explain the logic in popular words again: building bridges

(1) There is a ravine between the two pieces of land, and a bridge must be built to communicate between the two places;

(2) Build a bridge pier first on the first piece of land, and build a bridge pier on the second piece of land;

(3) The bridge piers are connected by bridges.

(4) The train on this side of the bridge and the train on the other side of the bridge exchange carriages for delivery, and the car on this side exchanges delivery with the car on the other side.

Similar to:

(1) The class of mainwindow and the new class defined are equivalent to two fields;

(2) Trains and cars are equivalent to members of each class. If you want to deliver goods, you must be train-to-train and car-to-car.Cars are like ui controls, trains are like other defined variables;

(3) The two classes must have the same members, and there must be trains and cars on both sides.So the class of mainwindow must define a new class (step 2), and the new class must define the class of mainwindow (step 5);

(4) The setmainwindow defined by the mainwindow class is equivalent to a bridge pier, which is built first.

(5) The function in setmainwindow connects the two, which is the bridge (the fourth step).

In this way, the car in the new class can be delivered directly to the car (ui control) in the mainwindow.

Step 7: You can use m_p to associate the ui control, and then draw the picture again. See the previous article for the graph function and the like, which is very detailed.Of course, it can also be other controls. I have tried changing the size and text of the button, and they can all be used.

 m_pWinMain->ui->PLOTVSAMP->graph(0)->setData(gvUTCms,gvUTCms);m_pWinMain->ui->PLOTVSAMP->replot();

Part II: Summary

The overall steps are the same as the logic in "QT-based Real-time Waveform Display of CAN Communication Data (Serial Seven) ==== "Data Transmission of Different Classes", which should be well understood.

There are milliseconds in the CAN frame, send the ms number to the new class (thread), start the thread in the main program, and draw a picture, you can get the correct graphics.The left side is the CAN frame display program made in the previous article, and the right side waveform is the drawing in the UI interface in the new class.

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