C++/Qt Threads error without using threads - c++

Question

I am using a special form of the qt framework and it will look a bit complicated. But do not worry. It is the same as the original framework of qt. (And no I can't change it)
My intention of this program is to load a table in a tableview from the ui. The tableview should have as many rows and text as files that are in a directory. I take all files in the directory and put an filter on them. Only the selected one are counted and used afterwards.
And now to my problem:
I want to display the table like an Excel table: it should highlight the cell where my cursor (in my example it is an counter which goes up and down) stands right now (Currently I do not have a cursor, so I have to use a self-created "cursor". You will see it in the program what I mean).
I use a QStandardItemModel to display it and a QStandardItem to define it.
Because I want to change the color of the cells I use an QStandardItem array to save the cells one by one.
form.h:
#ifndef FORM_H
#define FORM_H
#include <QWidget>
#include <QTextTable>
#include <QFont>
#include <QFile>
#include <QDir>
#include <QTextStream>
#include <QString>
#include <QStringList>
#include <QStandardItemModel>
#include <QStandardItem>
#include <QBrush>
namespace Ui {
class Form;
}
class Form : public QWidget
{
Q_OBJECT
public:
explicit Form(QWidget *parent = 0);
~Form();
void my_setCFGFromDirectory();
void my_Highlighted(int, bool);
void my_loadCFG(int);
private:
Ui::Form *ui;
QFile file;
QTextStream textstream;
QDir directory;
QString filename;
QStringList stringlist;
QStringList filter;
QStandardItemModel *model;
QStandardItem *tableitem;
QStandardItem* pointerTableitem[];
int max_files;
int w_counter;
bool check1;
bool check2;
bool check3;
};
#endif // FORM_H
and the
form.cpp
#include "form.h"
#include "ui_form.h"
#include "rbobject.h"
Form::Form(QWidget *parent) :
QWidget(parent),
ui(new Ui::Form)
{
ui->setupUi(this);
}
Form::~Form()
{
delete ui;
}
void Form::my_Highlighted(int actual_count, bool modus){
if(modus == 1){
w_counter = 0;
while(w_counter < max_files){
if(w_counter == actual_count){
pointerTableitem[w_counter]->setBackground(QBrush(QColor(130,180,255)));
}
w_counter++;
}
}
else
{
w_counter = 0;
while(w_counter < max_files){
pointerTableitem[w_counter]->setBackground(QBrush(QColor(255,255,255)));
w_counter++;
}
}
}
void Form::my_setCFGFromDirectory(){
directory.setPath("/etc/rosenbauer/CFG-Files");
filter << "*_CFG.ini";
stringlist = directory.entryList(filter); //takes the selected files and wriths them in a filelist
max_files = stringlist.count(); //Counts the selected files
pointerTableitem [max_files];
memset(pointerTableitem, 0, max_files*sizeof(int)); //The compiler can not see how many elements should be in the array at the time he constructs the array.
//So you have to use this to tell the compiler, how many elements it should create
model = new QStandardItemModel(max_files, 1, this); //Rows , Columns , this
model->setHorizontalHeaderItem(0, new QStandardItem(QString("CFG-Files"))); //Column , QStandarditem...name
for(w_counter = 0; w_counter != max_files; w_counter++){
tableitem = new QStandardItem();
tableitem->setBackground(QBrush(QColor(255,255,255)));
tableitem->setText(QString(stringlist[w_counter])); //Wriths text in the cell
qDebug() << tableitem->text();
pointerTableitem[w_counter] = tableitem; //Stacks the tableitems in a filelist
model->setItem(w_counter, 0, tableitem); //Row, Column , tableitem...text
}
w_counter = 0;
//pointerTableitem[2]->setBackground(QBrush(QColor(130,180,255))); //Test
ui->TableConfig->setModel(model); //Sets the table into the UI
}
void Form::my_loadCFG(int file_position){
check1 = 0;
check2 = 0;
directory.setPath("/etc/rosenbauer/etc/rosenbauer");
check1 = directory.remove("SA008_890560-001_CFG.ini");
check2 = directory.remove("reparsed/SA008_890560-001_CFG.ini_reparsed");
if(check1 && check2){
filename = pointerTableitem[file_position]->text();
check3 = QFile::copy("/etc/rosenbauer/CFG-Files/"+filename, "/etc/rosenbauer/SA008_890560-001_CFG.ini");
if(!check3){
qDebug() << "Error! Could not copy new CFG-file into directory";
}
}
else
{
qDebug() << "Error! Could not delete running CFG-file(s) from directory";
}
}
The main header rbobject45000.h
#ifndef RbObject45000_H
#define RbObject45000_H
#include "rbobject.h"
#include "form.h"
class RbObject45000 : public RbObject{
public:
RbObject45000();
RbObject45000(qint32 rbObjectId, RDataObject *dataobject, qint32 style, QObject *parent = 0);
RbObject45000(qint32 rbObjectId, qint32 style, qint32 prio, QObject *parent);
bool entered_ui;
bool entered_key;
short counter;
short w_count;
short delay_count;
short max_files;
short begin;
short end;
Form *f;
void exec();
~RbObject45000();
};
#endif // RbObject45000_H
And this is the main:
rbobject45000.cpp
RbObject45000::RbObject45000(qint32 rbObjectId, qint32 style, qint32 prio, QObject *parent):
RbObject(rbObjectId, style, prio, parent){
entered_ui = 0;
entered_key = 0;
counter = 0;
w_count = 1; //... whilecounter
delay_count = 0; //... delay for the deadtime
max_files = 0;
begin = 0;
end = 0;
f= new Form(); //f...name of the displayed UI
}
void RbObject45000::exec(){
//Opens the file on the display
if(getKey(RB_KEY_9) && getKey(RB_KEY_7) && entered_ui ==0){
f->show();
entered_ui = 1;
// Geting the Files from Directory
f->my_setCFGFromDirectory();
}
// Prescind them file in the table
if(entered_ui == 1 && delay_count == 2){
if(getKey(RB_KEY_7)){
counter--;
entered_key = 1;
if(counter < 0){
counter = 0;
}
}
else if(getKey(RB_KEY_9)){
counter++;
entered_key = 1;
if(counter > max_files){
counter = max_files;
}
}
if(entered_key == 1){
while(w_count <= max_files){
f->my_Highlighted(w_count, 0); //Cell , not highlighted
w_count++;
}
w_count = 0;
f->my_Highlighted(counter,1); //Cell , highlighted
entered_key = 0;
}
delay_count = 0;
}
else if(delay_count == 2){ //if delay == 2 and nobody hit a button
delay_count = 0;
}
delay_count++;
//Load the coosen file as programm-config in
if(entered_ui == 1){
if(getKey(RB_KEY_8)){
f->my_loadCFG(counter);
}
}
}
(RB_KEY_7-9 are buttons of a hardware-module, only have to click them)
So if I do it like this, the program will compile and start. If I press the buttons and the program run into the my_setCFGFromDirectory() it exits the window and stop running, but if the QStandardItem pointerTableitem is declared in the my_setCFGFromDirectory() everything works fine (but the pointerTableitem needs to be private).
The errors I get are:
QObject: Cannot create children for a parent that is in a different thread.
(Parent is Form(0x167498), parent's thread is QThread(0x1414e8), current thread is QThread(0x15d2d8)
Segmentation fault
It appears to say I use a thread (I'm sure I don't). But I know it has something to do with pointerTableitem and the declaration in the header and cpp.

Answer 1

If I'm not mistaken the problem lies here:
model = new QStandardItemModel(max_files, 1, this);
You try to create a QStandardItemModel passing your Form instance this as a parent, the form was created on the main thread, this call apparently happens on another thread (the edits you made were not enough, it is still unclear if RbObject inherits QThread but you could check that yourself) and thus the error message.
Why not call the function on the main thread? Instead of doing this
f->show();
entered_ui = 1;
// Geting the Files from Directory
f->my_setCFGFromDirectory();
in a different thread, make a slot/signal pair for the Form class, put this code in the slot and fire the connected signal from RbObject45000::exec(). It is not correct to do UI manipulation from a non-UI trhead.