Picklist example as application

[davidmct]

Hi,

I'm redesigning my UI to make use of the new Maemo5 buttons etc and thought I'd start by taking the picklist example (http://qt.nokia.com/doc/qt-maemo-4.6...kselector.html) and modifying it to use a QMainWindow.

The original code compiles and runs fine.

creating a class thus:

class MainWindow : public QMainWindow {
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
....

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)

{
/// Test example
QStandardItemModel model(0, 1);
populateListModel(&model);

QVBoxLayout *layout = new QVBoxLayout;

QMaemo5ValueButton *button3 = new QMaemo5ValueButton("Value besides text");
button3->setValueLayout(QMaemo5ValueButton::ValueBesideText);
QMaemo5ListPickSelector *selector1 = new QMaemo5ListPickSelector;
selector1->setModel(&model);
// not setting the current index means that the value is empty.
//selector1->setCurrentIndex(1);
button3->setPickSelector(selector1);
layout->addWidget(button3);

button3->show();
}

Results in a window with no content but a title bar. using setLayout(layout) fails as QMainWindow has a defined layout.

Setting it up as a QDialog based class results in a small (half screen window) with no content.

Defining a new central QWidget thus...

QWidget *mainMan = new QWidget(this);
QMainWindow::setCentralWidget( mainMan);

QStandardItemModel model(0, 1, mainMan);
populateListModel(&model);

QVBoxLayout *layout = new QVBoxLayout (mainMan);

QMaemo5ValueButton *button3 = new QMaemo5ValueButton("Value besides text");
button3->setValueLayout(QMaemo5ValueButton::ValueBesideText);
QMaemo5ListPickSelector *selector1 = new QMaemo5ListPickSelector;
selector1->setModel(&model);
// not setting the current index means that the value is empty.
//selector1->setCurrentIndex(1);
button3->setPickSelector(selector1);

layout->addWidget(button3);
mainMan->setLayout(layout);
mainMan->show();

Results in the button being displayed fine but when selected displays a half size empty window rather than a pick list. I've tried to set the parent on the ValueButton and PickSelector but this has no effect.

This may be my ignorance on the window relationships or on QT generally but help and comment much appreciated. Advice on how to add a set of stacked windows with defined child widgets in each would be appreciated as, again, using the canned example doesn't work in the above MainWindow class definition even trying to be careful with parent/child relationships.

BR David

[divanov]

So you create model on the stack and it's destroyed, when constructor quits. You have to create it dynamically using operator new.

[davidmct]

Brilliant.

creating the model via new worked a treat.

Many thanks as always.

BR
David

[divanov]

Brilliant.

creating the model via new worked a treat.

Many thanks as always.

BR
David

Make sure you are passing this to constructor QStandardItemModel, otherwise you will have memory leak.

[davidmct]

Hi,

Can I just clarify. At the moment mainMan is a child widget of the application. I use new with mainMain then as the parent for QStandardItemModel:

QStandardItemModel *model = QStandardItemModel (0,1, mainMan);

I assume this will avoid a memory leak as mainMan takes control/ownership. Is that correct?

I'm using mainMan so I can control the layout within the main application window. Is there another way to set a layout in QMainWindow?

Many thanks,

David

[divanov]

Can I just clarify. At the moment mainMan is a child widget of the application. I use new with mainMain then as the parent for QStandardItemModel:

QStandardItemModel *model = QStandardItemModel (0,1, mainMan);

I assume this will avoid a memory leak as mainMan takes control/ownership. Is that correct?

I cannot say without a context. However, normally in constructor you use this.

I'm using mainMan so I can control the layout within the main application window. Is there another way to set a layout in QMainWindow?

You should use QMainWindow::setCentralWidget() as QMainWindow has a layout already.

QVBoxLayout *layout = new QVBoxLayout;
// add some widgets to layout
setCentralWidget(new QWidget);
centralWidget()->setLayout(layout);

[davidmct]

Hi,

I understand and your code is neater than mine and has same effect. However, if I want my central widget to have stacked windows then how would I approach this?

If I use my approach of

QWidget *mainMan = new QWidget(this);
QMainWindow::setCentralWidget( mainMan);
mainMan->setAttribute(Qt::WA_Maemo5StackedWindow);

I assume I can add another stacked window using ...

QPushButton button2("Click here to open another stacked window", mainMan);
button2.setAttribute(Qt::WA_Maemo5StackedWindow);
button2.setWindowFlags(button2.windowFlags() | Qt::Window);

I can then show these windows using show().

In your suggestion of

QVBoxLayout *layout = new QVBoxLayout;
// add some widgets to layout
setCentralWidget(new QWidget);
centralWidget()->setLayout(layout);

Could I have a set of layouts that I can overlay on the centralWidget by repeatedly calling setLayout? How else could I achieve this?

What I'm trying to achieve is an initial window with a number of buttons which when clicked bring up new windows containing new layouts. QDialog might achieve this effect as various data are to be entered but I prefer the look of sliding windows and persistence of information.

Hope this makes sense
Thanks,
David

[divanov]

I understand and your code is neater than mine and has same effect.

Almost.

QWidget *mainMan = new QWidget(this);
QMainWindow::setCentralWidget( mainMan);
mainMan->setAttribute(Qt::WA_Maemo5StackedWindow);

This will compile but makes no sense. You set Qt::WA_Maemo5StackedWindow attribute to windows only.
You don't need QMainWindow::

QPushButton button2("Click here to open another stacked window", mainMan);
button2.setAttribute(Qt::WA_Maemo5StackedWindow);
button2.setWindowFlags(button2.windowFlags() | Qt::Window);

This is wrong since mainMan is not a window. Making window from button is also Ok, but probably you never do that in real life.
There is an example here:
http://wiki.forum.nokia.com/index.ph...ows_in_Maemo_5

Could I have a set of layouts that I can overlay on the centralWidget by repeatedly calling setLayout? How else could I achieve this?

What will happen, if you repeatedly call setLayout is written in documentation.
http://qt.nokia.com/doc/4.6/qwidget.html#setLayout