How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?

embdev

Suppose I've my existing C source codes to run on my embedded Linux board and i'd like to create a Qt GUI using e.g. QtWidget application. How do I exactly integrate the Qt GUI and C source codes together? e.g. if I create a GUI to playback video, how to link e.g. a [Open] button to trigger e.g. a video decoder block that will run on my embedded Linux?

jsulm

@embdev Read http://doc.qt.io/qt-5.7/signalsandslots.html
C can be easily called from C++. You can simply add your C code to your Qt project. Or you can build your C code as a library and link it to your Qt application.

embdev

@jsulm I see, so more specifically on the implementation level, suppose I create a QtWidget application project, and I've the embedded hardware source codes, should it be a stand alone source page or I should merge inside, say in the mainwindow.cpp?

jsulm

@embdev You should not merge it. What would be the benefit? Keep it separated from your UI code.

embdev

@jsulm okies, so implementation level is that i'll have a UI source, then it'll call on to the functions in my embedded C code to execute certain features on my embedded Linux board.

In that sense, my kit, especially my qmake.exe needs to be correctly setup so that when I build, the qmake.exe will build my C codes as well as the GUI codes using my compiler right?

jsulm

@embdev No need to change anything in your kit. Just use .c suffix instead of .cpp for your C code the build system is smart enough to find out which compiler (gcc for C and g++ for C++) to call.
You just need to add that C files to your .pro file as you do for C++ files.

embdev

@jsulm got it. so suppose I've added my embedded Linux .c file and then I created a UI button, By using signals & slots feature in Qt, I can link the button to triggering a particular f(x) in my .c file to run some processes on my embedded Linux board. is this train of thought correct?

jsulm

@embdev Yes, it is. Include the C header file where your C function is declared.

embdev

@jsulm greatly appreciate for the directions! I'll try it out!

embdev

@jsulm suppose I've created a QtWidget project with main.cpp and mainwindow.cpp sources created. I've also created a simple UI with pushButton to run a particular f(x) in another source code (that access my embedded Linux target directly)

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::on_pushButton_clicked()
{

SAMPLE_VDEC_VdhH264();

}

The SAMPLE_VDEC_VdhH264(); is actually defined in my embedded source code as one of the options. Is it okay to add the function just like that? as I met with build error saying that that function is not declared in this scope.

mrjj

Hi
You need to include the header file also

#include "VDEC_VdhH264.H" or where ever
SAMPLE_VDEC_VdhH264()
is declared.

embdev

@mrjj I see. Well, because I've a main.c source file from vendor as sample program, which I've also added into Qt projects. And i'd like to link pushbutton I've created in mainwindow.mpp source file to link to my vendor sample source file function [i.e. SAMPLE_VDEC_VdhH264(); ], Hence there's no header file for the high-level function, as the high-level function is defined in the sample source file.

Does it mean I've to create a separate header file to include the high-level functions in the sample source file, so that I can add the header file into mainwindow.mpp, containing the high-level function defined in my sample source file, and that I can then just call the functions accordingly?

mrjj

Hi
I would make a new .h file for it as not to be messy.
This file would list the functions from main.c

However, if the main.cpp is included in the project, you can use without .h file like this

void/int SAMPLE_VDEC_VdhH264(); //// forward declare it

void MainWindow::on_pushButton_clicked()
{
SAMPLE_VDEC_VdhH264(); // call it
}

embdev

@mrjj I've included the headers from my sample source file in main.mpp as well, with the SAMPLE_VDEC_VdhH264 function declaration.

In mainwindow.cpp

#include "mainwindow.h"
#include <QApplication>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/time.h>
#include <fcntl.h>
#include <errno.h>
#include <pthread.h>
#include <math.h>
#include <unistd.h>
#include <signal.h>
#include "sample_comm.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

int SAMPLE_VDEC_VdhH264();

return a.exec();

}

In mainwindow.cpp, invoke the function SAMPLE_VDEC_VdhH264

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::on_pushButton_clicked()
{

SAMPLE_VDEC_VdhH264();

}

I tried to build again but it says the same error though (i.e. in mainwindow.cpp, 'SAMPLE_VDEC_VdhH264 was not declared in this scope')

mrjj

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

int SAMPLE_VDEC_VdhH264(); <<<< why here??? that is forward in main. not what i ment.

return a.exec();
}

Did you make a .h file with ?
int SAMPLE_VDEC_VdhH264();

else
i mean like

int SAMPLE_VDEC_VdhH264();

void MainWindow::on_pushButton_clicked()
{

SAMPLE_VDEC_VdhH264();

}

embdev

@mrjj my apologies, I've read it otherwise. However, it seems that the compiler can't find my function definition. It's a separate source code which I've added into the project entitled "sample_vdec.c". The function definition in this source code is:

HI_S32 SAMPLE_VDEC_VdhH264(HI_VOID)
{
....................
}

I've amended to the following:

in mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "hi3536mainfx.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

HI_U32 SAMPLE_VDEC_VdhH264();

void MainWindow::on_pushButton_clicked()
{

SAMPLE_VDEC_VdhH264();

}

in main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}

in header

#ifndef HI3536MAINFX_H
#define HI3536MAINFX_H
#include <hi_type.h>
#include <hi_comm_vb.h>

typedef struct hiVDEC_USERPIC_S
{
HI_U32 u32PicWidth;
HI_U32 u32PicHeigth;
VB_POOL u32PoolId;
VB_BLK u32BlkHandle;
HI_U32 u32PhyAddr;
HI_VOID *pVirAddr;
}VDEC_USERPIC_S;

HI_U32 SAMPLE_VDEC_VdhH264();

#endif // HI3536MAINFX_H

mrjj

since you have a
HI3536MAINFX_H
with
HI_U32 SAMPLE_VDEC_VdhH264();

you dont need it over
void MainWindow::on_pushButton_clicked()
also.

so compiles now?

embdev

@mrjj discovered some error in datatype in my code but rectified it but still unable to compile. The error says undefined reference to SAMPLE_VDEC_VhdH264(); and ld returned 1 exit status.
When I highlighted VDEC_SAMPLEVhdH264(); in main.cpp and hit [F2] cursor recursively, it brings me to the sample source code where this function is defined but doesn't brings me to the header where I declared this function.

in main.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "hi3536mainfx.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pushButton_clicked()
{

   SAMPLE_VDEC_VdhH264();

}

in sample source code where SAMPLE_VDEC_VhdH264() is defined:

HI_S32 SAMPLE_VDEC_VdhH264(HI_VOID)
{
    VB_CONF_S stVbConf, stModVbConf;
    HI_S32 i, s32Ret = HI_SUCCESS;
    VDEC_CHN_ATTR_S stVdecChnAttr[VDEC_MAX_CHN_NUM];
    VdecThreadParam stVdecSend[VDEC_MAX_CHN_NUM];
    VPSS_GRP_ATTR_S stVpssGrpAttr[VDEC_MAX_CHN_NUM];
 ..... ..... .....
}

in my header file

#ifndef HI3536MAINFX_H
#define HI3536MAINFX_H
#include "hi_comm_vb.h"
#include "hi_type.h"

typedef struct hiVDEC_USERPIC_S
{
    HI_U32   u32PicWidth;
    HI_U32   u32PicHeigth;
    VB_POOL  u32PoolId;
    VB_BLK   u32BlkHandle;
    HI_U32   u32PhyAddr;
    HI_VOID  *pVirAddr;
}VDEC_USERPIC_S;

HI_S32 SAMPLE_VDEC_VdhH264(HI_VOID);

#endif // HI3536MAINFX_H

jsulm

@embdev said in How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?:

in sample source code where SAMPLE_VDEC_VhdH264() is defined:

Is the source file containing SAMPLE_VDEC_VhdH264() part of your project and is it built?

embdev

@jsulm yes it is, the source file containing the function definition SAMPLE_VDEC_VhdH264() is added physically into the project file.

How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?

In mainwindow.cpp

In mainwindow.cpp, invoke the function SAMPLE_VDEC_VdhH264

in mainwindow.cpp:

in main.cpp

in header

** in main.cpp **

** in sample source code where SAMPLE_VDEC_VhdH264() is defined: **

** in my header file **

in main.cpp

in sample source code where SAMPLE_VDEC_VhdH264() is defined:

in my header file