Why am I not getting a display in my Qt Widget?

Question

When I run it it will just finish right away and not show anything. I can't find anything wrong w/it and no one on #qt could either. I've got other apps working fine so I'm not sure. It's got something to do with the createForm call, if I omit that call in the constructor I do get a default QWidget displayed.

captchit.pro

    #-------------------------------------------------
    #
    # Project created by QtCreator 2011-02-26T20:58:23
    #
    #-------------------------------------------------

QT       += core gui network

TARGET = captchit
TEMPLATE = app

SOURCES += main.cpp\
        widget.cpp

HEADERS  += widget.h

main.cpp

    #include "QtGui/QApplication"
    #include "widget.h"

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

return a.exec();


}

widget.h

    #ifndef WIDGET_H
    #define WIDGET_H

#include <QWidget>


class QPixmap;
class QLabel;
class QLineEdit;
class QPushButton;

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);

private slots:
    void on_refreshButton_pressed();
    void on_submitButton_pressed();
    void on_closeButton_pressed();

private:
    QPixmap captchaImage;
    QLabel *imageLabel;
    QLabel *statusLabel;
    QLineEdit *captchaLineEdit;
    QPushButton *submitButton;
    QPushButton *refreshButton;
    QPushButton *closeButton;

void createForm();
void createActions();
void getCaptcha();
void submitCaptcha();


};

endif // WIDGET_H

widget.cpp

    #include "widget.h"
    #include "QtNetwork/QtNetwork"
    #include "QtGui"

void Widget::on_refreshButton_pressed()
{
    ;
}

void Widget::on_submitButton_pressed()
{
    ;
}

void Widget::on_closeButton_pressed()
{
    ;
}

// Create UI Components
void Widget::createForm()
{
    // Create Main Layout
    QVBoxLayout *mainLayout = new QVBoxLayout(this);

//    // set captcha pixmap to imageLabel for displaying
//    imageLabel->setPixmap(captchaImage);

// Create Buttons
QVBoxLayout *buttonLayout = new QVBoxLayout();
submitButton->setText("Submit");
refreshButton->setText("Refresh");
closeButton->setText("Close");
buttonLayout->addWidget(submitButton);
buttonLayout->addWidget(refreshButton);
buttonLayout->addWidget(closeButton);

// Complete Layouts
// lineEdit & submitStatus
QVBoxLayout *lineEditLayout = new QVBoxLayout();
lineEditLayout->addStretch();
lineEditLayout->addWidget(statusLabel);
lineEditLayout->addWidget(captchaLineEdit);
lineEditLayout->addStretch();

// Create Bottom Layout
QHBoxLayout *bottomLayout = new QHBoxLayout();
bottomLayout->addLayout(lineEditLayout);
bottomLayout->addLayout(buttonLayout);

// Add to mainLayout


//    mainLayout->addWidget(imageLabel);
    mainLayout->addLayout(bottomLayout);
    setLayout(mainLayout);
}

// Bind Slots and Signals
void Widget::createActions()
{
    ;
}

void Widget::getCaptcha()
{
    ;
}

void Widget::submitCaptcha()
{
    ;
}

Widget::Widget(QWidget *parent) :
    QWidget(parent)
{
    createForm();
//    createActions();
}

Terence Simpson · Accepted Answer · 2011-02-27 05:16:56Z

3

You need to initialize your private class members, probably in your constructor, before you use them.

Widget::Widget(QWidget* parent) :
    QWidget(parent)
{
    captchaImage = new QPixmap;
    imageLabel = new QLabel(this);
    statusLabel = new QLabel(this);
    captchaLineEdit = new QLineEdit(this);
    submitButton = new QPushButton(this);
    refreshButton = new QPushButton(this);
    closeButton = new QPushButton(this);

    createForm();
//    createActions();
}

Also note that QPixmap does not derive from QObject, so you'll have to delete it manually. It may be better to remove the QPixmap *captchaImage member from your class and use temporary QPixmap objects in your code.

answered Feb 27, 2011 at 5:16

Terence Simpson

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kryptobs2000 · Accepted Answer · 2011-02-27 05:21:36Z

0

Oops, it was because I forgot to initialize all of my components, herp derp.

answered Feb 27, 2011 at 5:21

kryptobs2000

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