attach more widgets to a QScrollArea

[wysota]

That's not the way to go, really... Nevertheless, I don't see the problem. Would you care to explain?

[franco.amato]

That's not the way to go, really... Nevertheless, I don't see the problem. Would you care to explain?

Which is the way to go?

Well the problem is that the widget doesn't fit the scroll area.
I'm not sure the logic I used is correct ( assign the correct parent of every widget )

[pezmaster31]

Not sure if this is the ideal way to achieve this sort of behavior... but this seems to work on my end (if I understand you correctly)

// set size policy for your WaveDisplay widget to use as much vertical space on its parent as is available
m_WaveDisplay->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
 
QVBoxLayout* il = new QVBoxLayout;
il->setSpacing(0);
il->addWidget(m_TimeDisplay);
il->addWidget(m_WaveDisplay);
 
QWidget* w = new QWidget();
// you had the widget's vertical size policy set to Fixed, so there's no way it could ever expand vertically, changed to Ignored (same as WaveDisplay)
// w->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
w->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
w->setMinimumSize(800, 271); // 271 = 250(m_WaveDisplay) + 20(m_TimeDisplay) + 1
w->setLayout(il);
 
QScrollArea* sa = new QScrollArea;
sa->setWidgetResizable(true);
sa->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
sa->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
sa->setWidget(w);

// set size policy for your WaveDisplay widget to use as much vertical space on its parent as is available
m_WaveDisplay->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);

QVBoxLayout* il = new QVBoxLayout;
il->setSpacing(0);
il->addWidget(m_TimeDisplay);
il->addWidget(m_WaveDisplay);

QWidget* w = new QWidget();
// you had the widget's vertical size policy set to Fixed, so there's no way it could ever expand vertically, changed to Ignored (same as WaveDisplay)
// w->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
w->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
w->setMinimumSize(800, 271); // 271 = 250(m_WaveDisplay) + 20(m_TimeDisplay) + 1
w->setLayout(il);

QScrollArea* sa = new QScrollArea;
sa->setWidgetResizable(true);
sa->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
sa->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
sa->setWidget(w);

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[franco.amato]

Not sure if this is the ideal way to achieve this sort of behavior... but this seems to work on my end (if I understand you correctly)

// set size policy for your WaveDisplay widget to use as much vertical space on its parent as is available
m_WaveDisplay->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
 
QVBoxLayout* il = new QVBoxLayout;
il->setSpacing(0);
il->addWidget(m_TimeDisplay);
il->addWidget(m_WaveDisplay);
 
QWidget* w = new QWidget();
// you had the widget's vertical size policy set to Fixed, so there's no way it could ever expand vertically, changed to Ignored (same as WaveDisplay)
// w->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
w->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
w->setMinimumSize(800, 271); // 271 = 250(m_WaveDisplay) + 20(m_TimeDisplay) + 1
w->setLayout(il);
 
QScrollArea* sa = new QScrollArea;
sa->setWidgetResizable(true);
sa->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
sa->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
sa->setWidget(w);

// set size policy for your WaveDisplay widget to use as much vertical space on its parent as is available
m_WaveDisplay->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);

QVBoxLayout* il = new QVBoxLayout;
il->setSpacing(0);
il->addWidget(m_TimeDisplay);
il->addWidget(m_WaveDisplay);

QWidget* w = new QWidget();
// you had the widget's vertical size policy set to Fixed, so there's no way it could ever expand vertically, changed to Ignored (same as WaveDisplay)
// w->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
w->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Ignored);
w->setMinimumSize(800, 271); // 271 = 250(m_WaveDisplay) + 20(m_TimeDisplay) + 1
w->setLayout(il);

QScrollArea* sa = new QScrollArea;
sa->setWidgetResizable(true);
sa->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
sa->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
sa->setWidget(w);

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Hi now the widget fit the scroill area but I still have some problems.
1) when I resize the widget ( for example user zoom in ) the widget seems to pulse. It grow and shrank (in the orizontally direction that must be fixed) continuosly every time user press zoom button
2) The scroll bar is not shown. The widget grow ( in a bad way ) but I can not navigate in it with the scroll bar.

May be my code of zoom is not correct.
This is the code

// executed when user press zoonin button
void WaveWidget::zoomIn()
{
	float f = m_ZoomFactor + 0.12;
	qDebug() << "WaveWidget::zoomIn - f: " << f;
	m_WaveDisplay->setZoomFactor( f );
}

// executed when user press zoonin button
void WaveWidget::zoomIn()
{
	float f = m_ZoomFactor + 0.12;
	qDebug() << "WaveWidget::zoomIn - f: " << f;
	m_WaveDisplay->setZoomFactor( f );
}

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And then the code to expand the WaveDisplay

/************************************************************************/
/* setZoomFactor                                                                                                                   */  
/************************************************************************/ 
void WaveDisplay::setZoomFactor( float f )
{
	int w, h;
 
	w = width() * f;
	h = height();
 
	setMinimumSize( w, h );
	QWidget* p = dynamic_cast<QWidget*>( parent() );
	if (p)
		resize( p->width(), p->height() );
	repaint();
}

/************************************************************************/
/* setZoomFactor                                                                                                                   */  
/************************************************************************/ 
void WaveDisplay::setZoomFactor( float f )
{
	int w, h;

	w = width() * f;
	h = height();

	setMinimumSize( w, h );
	QWidget* p = dynamic_cast<QWidget*>( parent() );
	if (p)
		resize( p->width(), p->height() );
	repaint();
}

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I'm sure my code is wrong but I don't know where...
The zoom is wrote in very few time and I'm not sure is a correct way to do it.
The code of the zoom of TimeDisplay is not implemented yet..

Regards

[franco.amato]

I changed the code of the zoom so:

/************************************************************************/
/* setZoomFactor                                                                                                                   */  
/************************************************************************/ 
void WaveDisplay::setZoomFactor( float f )
{
	int w, h;
 
	w = width() * f;
	h = height();
 
	setMinimumSize( w, h );
	QWidget* p = dynamic_cast<QWidget*>( parent() );
	if (p)
	{
		//resize( p->width(), p->height() );
		resize(w, h); // <--------------------------------------------------------CHANGED
	}
 
	repaint();
}

/************************************************************************/
/* setZoomFactor                                                                                                                   */  
/************************************************************************/ 
void WaveDisplay::setZoomFactor( float f )
{
	int w, h;

	w = width() * f;
	h = height();

	setMinimumSize( w, h );
	QWidget* p = dynamic_cast<QWidget*>( parent() );
	if (p)
	{
		//resize( p->width(), p->height() );
		resize(w, h); // <--------------------------------------------------------CHANGED
	}

	repaint();
}

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And now I don't get the "grow and shrank" effect when I zoom. But the status bar still doesn't appear.
I can not navigate into the wave.
Any idea?

Best

[wysota]

The zoom is wrote in very few time and I'm not sure is a correct way to do it.

Defintely not

You are artificially manipulating the size of each child widget which is not a very good idea. Using graphics view or implementing everything as one widget derived from QAbstractScrollArea would be a much better approach.

[franco.amato]

Defintely not

You are artificially manipulating the size of each child widget which is not a very good idea. Using graphics view or implementing everything as one widget derived from QAbstractScrollArea would be a much better approach.

Thank you very much.
Can you give some line the code just to start the widget derived from QAbstractScrollArea?

Best

[wysota]

I can't give you a complete 10 line sample. I can tell you it is just like any ordinary widget with exception that at each time you only see part of it and the part seen is manipulated using QAbstractScrollArea::scrollContentsBy() that you will need to implement.

[franco.amato]

I can't give you a complete 10 line sample. I can tell you it is just like any ordinary widget with exception that at each time you only see part of it and the part seen is manipulated using QAbstractScrollArea::scrollContentsBy() that you will need to implement.

Why I can not inherits from QScrollArea instead of QAbstractScrollArea?

[wysota]

You can but in my opinion this is a bad idea for the functionality you are trying to implement.

[franco.amato]

You can but in my opinion this is a bad idea for the functionality you are trying to implement.

Is a bit difficult...and I can not find a valid example

[wysota]

What is so difficult in it? As for examples, you have the code of Qt, you also have examples of classes that are derived from classes that are derived from QAbstractScrollArea (like views in Item Views).

[franco.amato]

What is so difficult in it? As for examples, you have the code of Qt, you also have examples of classes that are derived from classes that are derived from QAbstractScrollArea (like views in Item Views).

I can not find such example in my Qt 4.6.0 installation

[wysota]

Which is the way to go?

Either a completely custom widget derived from QAbstractScrollArea or Graphics View.

Well the problem is that the widget doesn't fit the scroll area.

setWidgetResizable(true) would fix the problem.

[franco.amato]

Either a completely custom widget derived from QAbstractScrollArea or Graphics View.


setWidgetResizable(true) would fix the problem.

Hi, I already set it to true. It doesn't solve the problem. I posted above the most important code. If you can give a look you can see that the setWidgetResizable(true) is set to true

[franco.amato]

Either a completely custom widget derived from QAbstractScrollArea or Graphics View.

I can rewrite it if it's the case. Can you give me some hints on how to do it? As now I inherited from QWidget.
I wrote WaveWidget : QWidget.
WaveWidget contains vertically aligned
1) TimeDisplay : QWidget
2) WaveDisplay : QWidget

I would attach a QScrollArea to WaveWidget as I said to allow user zoom without results