How to stop multiple appearance of a widget

[Sarma]

hi sunil,
well, thanks for your help. But no where I have found the code that you have written previously. In which file should I see that . And can you please tell me how to generate the .ui files and use them in our ordinary program.

Thanks & regards,
Sarma.

[wysota]

See the FAQ.

[Sarma]

sir,
Iam getting errors as I said previously . Kindly show me the changes that I have to make in my code(I have send it in my first post).

Thanks & regards,
Sarma.

[wysota]

Look at the FAQ entry I mentioned. The code is there -- literally. Especially note the "static" keyword.

[Sarma]

sir,
I have modified my code like this:

CPT::CPT(QWidget *parent):QWidget(parent)
      {
         //some other lines of code
         QPushButton *but=new QPushButton(this);
         QObject::connect(but,SIGNAL(clicked()),this,SLOT(findbox()));
         //remaining program
       }
      void CPT::findbox()
       {
          QWidget  *fwin=new QWidget;
           //other widgets added to it
           //fwin->show();
           static fwin *form2 = new fwin(this);
           form2->show();
           form2->activateWindow(); // or form2->setActiveWindow() in Qt3
           form2->raise();
        }

CPT::CPT(QWidget *parent):QWidget(parent)
      {
         //some other lines of code
         QPushButton *but=new QPushButton(this);
         QObject::connect(but,SIGNAL(clicked()),this,SLOT(findbox()));
         //remaining program
       }
      void CPT::findbox()
       {
          QWidget  *fwin=new QWidget;
           //other widgets added to it
           //fwin->show();
           static fwin *form2 = new fwin(this);
           form2->show();
           form2->activateWindow(); // or form2->setActiveWindow() in Qt3
           form2->raise();
        }

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And I got the following errors:

"cptdebug.cpp", line 1501: Error: fwin, of type int, was previously declared QWidget*.
"cptdebug.cpp", line 1501: Error: Multiple declaration for fwin.
"cptdebug.cpp", line 1501: Error: "," expected instead of "*".
"cptdebug.cpp", line 1502: Error: form2 is not defined.
"cptdebug.cpp", line 1503: Error: form2 is not defined.
"cptdebug.cpp", line 1504: Error: form2 is not defined.

Kindly tell me why? And give me the possible solution.

Thanks and regards,
Sarma.

[wysota]

The compiler already told you why...

void CPT::findbox(){
           static fwin *form2 = new fwin(this);
           form2->show();
           form2->activateWindow();
           form2->raise();
}

void CPT::findbox(){
           static fwin *form2 = new fwin(this);
           form2->show();
           form2->activateWindow();
           form2->raise();
}

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[Sarma]

Sir,
sorry for troubling you much. I couldnot get the proper solution.Please show the changes that I have to make in my code.

regards,
Sarma.

[wysota]

Well, I gave you the code in the previous post. What else do you want?

[Sarma]

hello Sir,
I have posted this thread long back but I couldnot get proper solution.

See the FAQ.

In that FAQ, it was written that "Assuming you have two form classes: Form1 and Form2 and that Form1 has a pushbutton "button" child and Form2 is derived from QDialog" .

But in my application, the find box which I want to show is not derived from QDialog. It is a widget to which many child widgets are added.
Here is the code that I have written:

CPT::CPT(QWidget  *parent):QWidget (parent)
{
   QPushButton *findbut=new QPushButton(this);
   QObject::connect(findbut,SIGNAL(clicked()),this,SLOT(findstr()));
}
 
void CPT::findstr()
{
  QWidget *fwin=new QWidget;
  fwin->setCaption("CP Trace Debug Tool : FIND");
  fwin->setFixedSize(320,125);
  fwin->setFont(QFont("SansSerif",9));  
  fwin->setBackgroundColor(c1);
 
  QVBoxLayout *fvbox=new QVBoxLayout(fwin);
  fvbox->setMargin(2);
  fvbox->setSpacing(6);  
 
  QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
  fhbox1->setMargin(2);
  fhbox1->setSpacing(8);
 
  QLabel *fl1=new QLabel("Find:",fwin);
  fl1->setBackgroundColor(c1);  
 
  fedit1=new QLineEdit(fwin);
 
  fch=new QCheckBox("Regular Expression",fwin);
  fch->setBackgroundColor(c1);
 
  fhbox1->addWidget(fl1);
  fhbox1->addWidget(fedit1);
  fhbox1->addWidget(fch);
 
  QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
  fhbox2->setMargin(2);
  fhbox2->setSpacing(6);
 
  QPushButton *fb1=new QPushButton("Forward",fwin);
  fb1->setPaletteBackgroundColor(c1);
 
  QPushButton *fb2=new QPushButton("Backward",fwin);
  fb2->setPaletteBackgroundColor(c1);
 
  QPushButton *fb3=new QPushButton("Close",fwin);
  fb3->setPaletteBackgroundColor(c1);
 
  QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
  QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
  QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));
 
  fhbox2->addWidget(fb1);
  fhbox2->addWidget(fb2);
  fhbox2->addWidget(fb3);
 
  fwin->show();
}

CPT::CPT(QWidget  *parent):QWidget (parent)
{
   QPushButton *findbut=new QPushButton(this);
   QObject::connect(findbut,SIGNAL(clicked()),this,SLOT(findstr()));
}

void CPT::findstr()
{
  QWidget *fwin=new QWidget;
  fwin->setCaption("CP Trace Debug Tool : FIND");
  fwin->setFixedSize(320,125);
  fwin->setFont(QFont("SansSerif",9));  
  fwin->setBackgroundColor(c1);

  QVBoxLayout *fvbox=new QVBoxLayout(fwin);
  fvbox->setMargin(2);
  fvbox->setSpacing(6);  

  QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
  fhbox1->setMargin(2);
  fhbox1->setSpacing(8);

  QLabel *fl1=new QLabel("Find:",fwin);
  fl1->setBackgroundColor(c1);  

  fedit1=new QLineEdit(fwin);

  fch=new QCheckBox("Regular Expression",fwin);
  fch->setBackgroundColor(c1);
 
  fhbox1->addWidget(fl1);
  fhbox1->addWidget(fedit1);
  fhbox1->addWidget(fch);
 
  QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
  fhbox2->setMargin(2);
  fhbox2->setSpacing(6);

  QPushButton *fb1=new QPushButton("Forward",fwin);
  fb1->setPaletteBackgroundColor(c1);

  QPushButton *fb2=new QPushButton("Backward",fwin);
  fb2->setPaletteBackgroundColor(c1);

  QPushButton *fb3=new QPushButton("Close",fwin);
  fb3->setPaletteBackgroundColor(c1);

  QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
  QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
  QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));

  fhbox2->addWidget(fb1);
  fhbox2->addWidget(fb2);
  fhbox2->addWidget(fb3);

  fwin->show();
}

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Now when I press the button again and again, I get multiple windows of this findbox which I shouldn't. Kindly give me the possible solution.

Thanks & Regards,
Sarma.

[jpn]

You are always creating a new find dialog each and every time the button is pressed.
Move the find widget as a member variable, instantiate it only once, and connect the find buttons clicked() signal to the find widget's show() slot.

CPT::CPT(QWidget  *parent):QWidget (parent)
{
	createFind();
	QPushButton *findbut=new QPushButton(this);
	QObject::connect(findbut,SIGNAL(clicked()),fwin,SLOT(show()));
}
 
void CPT::createFind()
{
	// add "QWidget* fwin" as a member variable
	fwin=new QWidget;
	fwin->setCaption("CP Trace Debug Tool : FIND");
	fwin->setFixedSize(320,125);
	fwin->setFont(QFont("SansSerif",9)); 
	fwin->setBackgroundColor(c1);
 
	QVBoxLayout *fvbox=new QVBoxLayout(fwin);
	fvbox->setMargin(2);
	fvbox->setSpacing(6); 
 
	QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
	fhbox1->setMargin(2);
	fhbox1->setSpacing(8);
 
	QLabel *fl1=new QLabel("Find:",fwin);
	fl1->setBackgroundColor(c1); 
 
	fedit1=new QLineEdit(fwin);
 
	fch=new QCheckBox("Regular Expression",fwin);
	fch->setBackgroundColor(c1);
 
	fhbox1->addWidget(fl1);
	fhbox1->addWidget(fedit1);
	fhbox1->addWidget(fch);
 
	QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
	fhbox2->setMargin(2);
	fhbox2->setSpacing(6);
 
	QPushButton *fb1=new QPushButton("Forward",fwin);
	fb1->setPaletteBackgroundColor(c1);
 
	QPushButton *fb2=new QPushButton("Backward",fwin);
	fb2->setPaletteBackgroundColor(c1);
 
	QPushButton *fb3=new QPushButton("Close",fwin);
	fb3->setPaletteBackgroundColor(c1);
 
	QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
	QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
	QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));
 
	fhbox2->addWidget(fb1);
	fhbox2->addWidget(fb2);
	fhbox2->addWidget(fb3);
 
	// removed this
	// fwin->show();
}

CPT::CPT(QWidget  *parent):QWidget (parent)
{
	createFind();
	QPushButton *findbut=new QPushButton(this);
	QObject::connect(findbut,SIGNAL(clicked()),fwin,SLOT(show()));
}

void CPT::createFind()
{
	// add "QWidget* fwin" as a member variable
	fwin=new QWidget;
	fwin->setCaption("CP Trace Debug Tool : FIND");
	fwin->setFixedSize(320,125);
	fwin->setFont(QFont("SansSerif",9)); 
	fwin->setBackgroundColor(c1);

	QVBoxLayout *fvbox=new QVBoxLayout(fwin);
	fvbox->setMargin(2);
	fvbox->setSpacing(6); 

	QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
	fhbox1->setMargin(2);
	fhbox1->setSpacing(8);

	QLabel *fl1=new QLabel("Find:",fwin);
	fl1->setBackgroundColor(c1); 

	fedit1=new QLineEdit(fwin);

	fch=new QCheckBox("Regular Expression",fwin);
	fch->setBackgroundColor(c1);

	fhbox1->addWidget(fl1);
	fhbox1->addWidget(fedit1);
	fhbox1->addWidget(fch);

	QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
	fhbox2->setMargin(2);
	fhbox2->setSpacing(6);

	QPushButton *fb1=new QPushButton("Forward",fwin);
	fb1->setPaletteBackgroundColor(c1);

	QPushButton *fb2=new QPushButton("Backward",fwin);
	fb2->setPaletteBackgroundColor(c1);

	QPushButton *fb3=new QPushButton("Close",fwin);
	fb3->setPaletteBackgroundColor(c1);

	QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
	QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
	QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));

	fhbox2->addWidget(fb1);
	fhbox2->addWidget(fb2);
	fhbox2->addWidget(fb3);

	// removed this
	// fwin->show();
}

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[Sarma]

hi jpn,
well thanks for replying.But that didnot solve my problem. Actually, I didnot put the entire code before you( sorry for that ). Thing is that I need to set certain values before createFind() is called. So, I have the code like( with the changes suggested by you ):

CPT::CPT(QWidget *parent):QWidget(parent) 
{
   QPushButton *findbox=new QPushButton();
   QObject::connect(findbox,SIGNAL(clicked()),this,SLOT(defaults()));
}
 
void CPT::defaults()
{
   //setting values for some variables (of integer type)
   createFind();
   fwin->show();
}
 
 void CPT::createFind()
{
  //QWidget *fwin is made as a member variable
  fwin=new QWidget;
  fwin->setCaption("CP Trace Debug Tool : FIND");
  fwin->setFixedSize(320,125);
  fwin->setFont(QFont("SansSerif",9));  
  fwin->setBackgroundColor(c1);
 
  QVBoxLayout *fvbox=new QVBoxLayout(fwin);
  fvbox->setMargin(2);
  fvbox->setSpacing(6);  
 
  QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
  fhbox1->setMargin(2);
  fhbox1->setSpacing(8);
 
  QLabel *fl1=new QLabel("Find:",fwin);
  fl1->setBackgroundColor(c1);  
 
  fedit1=new QLineEdit(fwin);
 
  fch=new QCheckBox("Regular Expression",fwin);
  fch->setBackgroundColor(c1);
 
  fhbox1->addWidget(fl1);
  fhbox1->addWidget(fedit1);
  fhbox1->addWidget(fch);
 
  QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
  fhbox2->setMargin(2);
  fhbox2->setSpacing(6);
 
  QPushButton *fb1=new QPushButton("Forward",fwin);
  fb1->setPaletteBackgroundColor(c1);
 
  QPushButton *fb2=new QPushButton("Backward",fwin);
  fb2->setPaletteBackgroundColor(c1);
 
  QPushButton *fb3=new QPushButton("Close",fwin);
  fb3->setPaletteBackgroundColor(c1);
 
  QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
  QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
  QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));
 
  fhbox2->addWidget(fb1);
  fhbox2->addWidget(fb2);
  fhbox2->addWidget(fb3);
 
  //  fwin->show();
}

CPT::CPT(QWidget *parent):QWidget(parent) 
{
   QPushButton *findbox=new QPushButton();
   QObject::connect(findbox,SIGNAL(clicked()),this,SLOT(defaults()));
}

void CPT::defaults()
{
   //setting values for some variables (of integer type)
   createFind();
   fwin->show();
}

 void CPT::createFind()
{
  //QWidget *fwin is made as a member variable
  fwin=new QWidget;
  fwin->setCaption("CP Trace Debug Tool : FIND");
  fwin->setFixedSize(320,125);
  fwin->setFont(QFont("SansSerif",9));  
  fwin->setBackgroundColor(c1);

  QVBoxLayout *fvbox=new QVBoxLayout(fwin);
  fvbox->setMargin(2);
  fvbox->setSpacing(6);  

  QHBoxLayout *fhbox1=new QHBoxLayout(fvbox);
  fhbox1->setMargin(2);
  fhbox1->setSpacing(8);

  QLabel *fl1=new QLabel("Find:",fwin);
  fl1->setBackgroundColor(c1);  

  fedit1=new QLineEdit(fwin);

  fch=new QCheckBox("Regular Expression",fwin);
  fch->setBackgroundColor(c1);
 
  fhbox1->addWidget(fl1);
  fhbox1->addWidget(fedit1);
  fhbox1->addWidget(fch);
 
  QHBoxLayout *fhbox2=new QHBoxLayout(fvbox);
  fhbox2->setMargin(2);
  fhbox2->setSpacing(6);

  QPushButton *fb1=new QPushButton("Forward",fwin);
  fb1->setPaletteBackgroundColor(c1);

  QPushButton *fb2=new QPushButton("Backward",fwin);
  fb2->setPaletteBackgroundColor(c1);

  QPushButton *fb3=new QPushButton("Close",fwin);
  fb3->setPaletteBackgroundColor(c1);

  QObject::connect(fb1,SIGNAL(clicked()),this,SLOT(result_for()));
  QObject::connect(fb2,SIGNAL(clicked()),this,SLOT(result_bck()));
  QObject::connect(fb3,SIGNAL(clicked()),fwin,SLOT(close()));

  fhbox2->addWidget(fb1);
  fhbox2->addWidget(fb2);
  fhbox2->addWidget(fb3);

  //  fwin->show();
}

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Now kindly show me changes that I can make in this program so that at any time only one box should be made visible.

Thanks & Regards,
Sarma.

[jpn]

....and you are still creating the dialog again and again.
You do not want to create a new instance of the dialog every time the button is pressed.

CPT::CPT(QWidget *parent):QWidget(parent)
{
	createFind(); // create the dialog ONLY ONCE
	QPushButton *findbox=new QPushButton();
	QObject::connect(findbox,SIGNAL(clicked()),this,SLOT(find()));
}
 
void CPT::find()
{
	// set your defaults here
	fwin->show();
	fwin->activateWindow();
	fwin->raise();
}
 
void CPT::createFind()
{
	fwin = new QWidget;
	// ...
}

CPT::CPT(QWidget *parent):QWidget(parent)
{
	createFind(); // create the dialog ONLY ONCE
	QPushButton *findbox=new QPushButton();
	QObject::connect(findbox,SIGNAL(clicked()),this,SLOT(find()));
}

void CPT::find()
{
	// set your defaults here
	fwin->show();
	fwin->activateWindow();
	fwin->raise();
}

void CPT::createFind()
{
	fwin = new QWidget;
	// ...
}

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[wysota]

hello Sir,
I have posted this thread long back but I couldnot get proper solution.

In that FAQ, it was written that "Assuming you have two form classes: Form1 and Form2 and that Form1 has a pushbutton "button" child and Form2 is derived from QDialog" .

But in my application, the find box which I want to show is not derived from QDialog. It is a widget to which many child widgets are added.

It's all the same for QWidget, you just have to pass 0 as the parent (meaning you'll get a memory leak if you don't free that memory yourself later). Why don't you use a QDialog subclass anyway?