QLineEdit Selection changed()

[Andrex_Qt]

hello I am implementing a keypad with QFrame and push buttons buttons. the input widget is LineEdit following is my code.

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


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

    connect(ui->b0_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b1_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b2_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b3_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b4_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b5_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b6_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b7_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b8_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b9_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->bminus_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->b_point_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->clear_5,SIGNAL( clicked() ), this, SLOT( handler() ));
    connect(ui->back_5,SIGNAL( clicked() ), this, SLOT( handler() ));

    op="";

}

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


/*-----------------------------------------------------------------------------------------------------------------
 keypad and related functions
------------------------------------------------------------------------------------------------------------------*/
void MainWindow::handler()
{
    QPushButton *buttons = (QPushButton *)sender();      //mapping signals
    ip = buttons->text();
    if (ip=="Clr")
    {
       switch(LineEdit_select)
            {
            case 0: ui->ln_1->clear(); break;
            case 1: ui->ln_2->clear(); break;
            case 2: ui->ln_3->clear(); break;
            case 3: ui->ln_4->clear(); break;
            default:break;
            }
      }    
    else if(ip=="Back")
   {
         switch(LineEdit_select)
                    {
                    case 0: 
                                op=ui->ln_1->text();
                                if(op!="")
                                     op.remove(op.length()-1,op.length();
                                ui->ln_1->setText(op); break;
                    case 1:                          
                                 op=ui->ln_2->text();
                                  if(op!="")
                                          op.remove(op.length()-1,op.length();
                                  ui->ln_2->setText(op); break;
                    case 2:                         
                                  op=ui->ln_3->text();
                                   if(op!="")
                                           op.remove(op.length()-1,op.length();
                                   ui->ln_3->setText(op); break;
                    case 3: 
                                 op=ui->ln_4->text();
                                  if(op!="")
                                           op.remove(op.length()-1,op.length();
                                  ui->ln_4->setText(op); break;
                    default:break;
                    }
   }
    else
   {
        op = ip;

    switch(LineEdit_select)
    {
        case 0: ui->ln_1->setText(ui->ln_1->text()+op); break;
        case 1: ui->ln_2->setText(ui->ln_2->text()+op); break;
        case 2: ui->ln_3->setText(ui->ln_3->text()+op); break;
        case 3: ui->ln_4->setText(ui->ln_4->text()+op); break;
        default:break;
    }
    }

}

void MainWindow::on_ln_1_selectionChanged()
{
    op="";
    LineEdit_select=0;
}

void MainWindow::on_ln_2_selectionChanged()
{
    op="";
    LineEdit_select=1;
}

void MainWindow::on_ln_3_selectionChanged()
{
    op="";
    LineEdit_select=2;
}
void MainWindow::on_ln_4_selectionChanged()
{
    op="";
    LineEdit_select=3;
}

void MainWindow::on_BCLx_clicked()
{
    this->close();
}

Code works Fine but i always have to double click on the lineEdits. ln_1 to ln_4 are the four lineEdits. I want this to work on single click. Any suggestions?

[jeremy_k]

Code works Fine but i always have to double click on the lineEdits. ln_1 to ln_4 are the four lineEdits. I want this to work on single click. Any suggestions?

Hi,

It's not clear what the single click or double click refers to. Is the intention to setFocus() on a QLineEdit?

As far as suggestions, it's hard without a complete, minimal working example.

For my taste, having many clicked signals connect to a single slot makes for a complicated slot implementation. Rather than an if/else chain to select the operation, and then a switch to select the input/output, I would use a slot per operation. The operations covered by the else clause can use a lambda to pass
differentiating arguments to a single slot.

Rather than LineEdit_select being an integer, it looks like a pointer to the current ui->ln_* could work instead.

eg:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    <type of ui->ln_*> *lineEdit_select = &ui->ln_1;
    connect(ui->b0_5, &Type::clicked, this, [&](){ this->on_number(QChar("0")); });
    connect(ui->b1_5, &Type::clicked, this, [&](){ this->on_number(QChar("1")); });
    connect(ui->clear_5, &Type::clicked, this, &MainWindow::on_clear);
}

void MainWindow::on_clear()
{
    lineEdit_select->clear();
}

void MainWindow::on_number(QChar number)
{
    lineEdit_text->setText(lineEdit_text->text() + number);
}

void MainWindow::on_ln_1_selectionChanged()
{
    lineEdit_select = &ui->ln_1;
}

[Andrex_Qt]

Thanks for the insight, still my issue was that you have to double click (mouse or touch) the LineEdit to get its selection. Now in place of LineEdit i have used TextEdit, it works on single click. Thanks again for the reply.