Looking for list-widget like string stack class

[pospiech]

I have messages (Qstrings), which shall be displayed in a list. but this list shall not be filled infinitly, mabe only 1000 items. Then for more items the first ones should be skipped.

So it is in principle exactly what happens in every console.

I was wondering if such a class already exists, so I do not need to reinvent it.

Matthias

[wysota]

There is QStringList which should suit your needs or QCache, but the first one is better - if you go over the limit, simply remove the first item.

[pospiech]

I see that QStringList is suitable for storing the messages, but how do I display them?

I could use

listwidget->clear();
listwidget->addItems(currentStringList );

listwidget->clear();
listwidget->addItems(currentStringList );

To copy to clipboard, switch view to plain text mode 

but that looks to be horrible slow, especially if it is called more than once a second.

[wysota]

Take a look at QStringListModel.

[pospiech]

Take a look at QStringListModel.

Looks interesting, but how do I combine that with a Gui. The class and the included example have no object that derives from QWidget.

[caduel]

QStringList aList;
// add contents
QStringListModel *slm=new QStringListModel(aList);
QListView *lv = new QListView;
lv->setModel(slm);

QStringList aList;
// add contents
QStringListModel *slm=new QStringListModel(aList);
QListView *lv = new QListView;
lv->setModel(slm);

To copy to clipboard, switch view to plain text mode 

// Note that the QStringListModel is not aware of (later) modifications to the list you originally passed! You have to update the model to keep the two in sync.

and when you want to change the model:

slm->setStringList(newContents);

slm->setStringList(newContents);

To copy to clipboard, switch view to plain text mode 

(better use insertRows/removeRows/setData, though, otherwise performance will suffer, there might be flickering and the user will lose his selection etc...)

HTH

[pospiech]

(better use insertRows/removeRows/setData, though, otherwise performance will suffer, there might be flickering and the user will lose his selection etc...)

I have never worked with a model class, but seem to understand everyhing you posted, except your last statement. Does it mean the whole idea does not work?

[wysota]

It means you shouldn't change the string list after you add it to the model because the model won't see the changes. You have to change contents of the model instead. I suggest you take a look at the docs.

[aamer4yu]

Or may be you can look at QListWidget

[pospiech]

Or may be you can look at QListWidget

As I wrote im my second post in this thread I know listwidget very well but expect not really a very good speed if I constantly remove the first item and add a new last one and that every second.

[pospiech]

My solution using the ideas posted here looks now like this:

#include "ui/ui_WidgetListStringStack.h"
#include <QtCore/QStringList>
#include <QtGui/QStringListModel>
#include <QtCore/QPointer>
 
class WidgetListStringStack : public QWidget, protected Ui_WidgetListStringStack
{
	Q_OBJECT
public:
	WidgetListStringStack(QWidget* parent = 0, Qt::WFlags flags = 0);
	virtual ~WidgetListStringStack();
 
private:
	QPointer<QStringListModel> StringListModel;
	QStringList StackList;
	int MaxStackSize;
 
public:
	void addMessage(QString & message);
	void setMaxStackSize(int value);
 
};

#include "ui/ui_WidgetListStringStack.h"
#include <QtCore/QStringList>
#include <QtGui/QStringListModel>
#include <QtCore/QPointer>

class WidgetListStringStack : public QWidget, protected Ui_WidgetListStringStack
{
	Q_OBJECT
public:
	WidgetListStringStack(QWidget* parent = 0, Qt::WFlags flags = 0);
	virtual ~WidgetListStringStack();

private:
	QPointer<QStringListModel> StringListModel;
	QStringList StackList;
	int MaxStackSize;

public:
	void addMessage(QString & message);
	void setMaxStackSize(int value);

};

To copy to clipboard, switch view to plain text mode 

WidgetListStringStack::WidgetListStringStack( QWidget* parent /*= 0*/, Qt::WFlags flags /*= 0*/ ) : QWidget(parent, flags)
{
	setupUi(this);
	setMaxStackSize(100);
	StringListModel=new QStringListModel();
}
 
 
WidgetListStringStack::~WidgetListStringStack()
{
}
 
void WidgetListStringStack::setMaxStackSize(int value)
{
	MaxStackSize = value;
}
 
void WidgetListStringStack::addMessage(QString & message)
{
	StackList.append(message);
	if (StackList.size() > MaxStackSize)
		StackList.removeFirst();
 
	StringListModel->setStringList(StackList);
 
	listView->setModel(StringListModel); 
}

WidgetListStringStack::WidgetListStringStack( QWidget* parent /*= 0*/, Qt::WFlags flags /*= 0*/ ) : QWidget(parent, flags)
{
	setupUi(this);
	setMaxStackSize(100);
	StringListModel=new QStringListModel();
}


WidgetListStringStack::~WidgetListStringStack()
{
}

void WidgetListStringStack::setMaxStackSize(int value)
{
	MaxStackSize = value;
}

void WidgetListStringStack::addMessage(QString & message)
{
	StackList.append(message);
	if (StackList.size() > MaxStackSize)
		StackList.removeFirst();
	
	StringListModel->setStringList(StackList);
	
	listView->setModel(StringListModel); 
}

To copy to clipboard, switch view to plain text mode 

I filled it using a timer with 100ms and it does not flicker and looks very smooth.

However I need to look at the last item by default. How do I reset the view at every addMessage() call ?

[wysota]

What do you mean by reset? You wish to scroll the view to the end? Just take a look at QAbstractItemView docs and you'll see.

Anyway, I'd rather use a simple model with a circular buffer with a regular QListView.