Qt-将QTableWidget的数据更改为另一个类的QTableWidget的数据

Question

I'm have two , one on a MainWindow ui and another on a Dialog ui. What I'm trying to do is copy the data from the Dialog's and paste it in the MainWindow's . What I have tried to do is use Qt's Slot's and Signals mechanism to copy the data. Below is the code I tried to use:

MainWindow.h:

#include "ui_mainwindow.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT

public:   
explicit MainWindow(QWidget *parent = 0);


~MainWindow();

public slots:
void SetTableDataSlot(QTableWidgetItem* EditData);
}

MainWindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "dialog.h"
Dialog *dialog;

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

MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
dialog = new Dialog(this);
connect(mEdit,SIGNAL(setTableDataSignal(QTableWidgetItem*)),
                 this,SLOT(setTableDataSlot(QTableWidgetItem*)));
dialog->show();
}

void MainWindow::setTableDataSlot(QTableWidgetItem* EditData){
for(int i = 0; i<ui->tableWidget->rowCount();++i){
    for(int j = 0; j<ui->tableWidget->columnCount();++j){
        ui->tableWidget->setItem(i,j,EditData->clone());
    }
  }
}

Dialog.h:

#include <QDialog>
#include <QTableWidget>


namespace Ui {
class dialog;
}

class dialog : public QDialog
{
Q_OBJECT

public:
explicit dialog(QWidget *parent = 0);

~dialog();
signals:
void setTableDataSignal(QTableWidgetItem *EditData);
}

Dialog.cpp:

#include "ui_mainwindow.h"
#include "mainwindow.h"
#include "editmode1.h"
#include "ui_editmode1.h"

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

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

void Dialog::on_pushButton_clicked()
{
for (int i=0; i<rows;++i){
    for(int j = 0; j<columns;++j){
        emit setTableDataSignal(ui->tableWidget->item(i,j);
    }
  }
}

Now the program compiles fine but when I click on the button on the dialog form, it copies the data from the last cell in the dialog table, and pastes it in every cell in the mainwindow table. If anyone can give me an explanation on what is wrong here and how it could be fixed I would be very grateful. Thanks in advance.

Answer 1

Your error is in this line:

ui->tableWidget->setItem(i,j,&EditData);

You pass a pointer of an object that live in the stack and will be destroyed at the end of the setTableDataSlot . Also you are trying to set the same object in all the table cells.

You have to create a new QTableWidgetItem for each cell.

Also the logic is wrong, because you are copying each cell of table A end put each copy into all cells of table B (cell [0, 0] of A in all cells of B, than cell [0, 1] of A in all cells of B and so on).

I suggest to change approach (for example get the table of the dialog from the main window and copy the cells, without passing all the QTableWidgetItem by signal-slot)

EDIT

You can use this function to copy the QTableItems from a table to another (not tested)

void copyTableContents(QTableWidget* sourceTable, QTableWidget* destTable)
{
    for(int r = 0; r < sourceTable->rowCount() && r < destTable->rowCount(); ++r)
    {
        for(int c = 0; c < sourceTable->columnCount() && c < destTable->columnCount(); ++c)
        {
            //delete old item if exists
            QTableWidgetItem* dItem = destTable->takeItem(r, c);
            if(dItem)
                delete dItem;
            QTableWidgetItem* sItem = sourceTable->item(r, c);
            if(sItem) //copy the item if exists
                destTable->setItem(r, c, sItem->clone());
        }
    }
}

You can create a function in the dialog that return the table pointer. You can emit a signal without parameters from dialog when the copy button is clicked. Connect this signal to a slot of the main window that get the table from the dialog and call the function to copy the items.