[Qt-interest] can I emit signals between windows?

[Sean Harmer]

Hi,

I think it is because you are emitting the deleteFromMapSig() signal in the 
constructor of the detailed window but this is created *before* you make the 
connection - and so the signal just disappears into the ether.

You need to create the object, connect the signal/slot, then emit the signal 
later in response to something interesting happening in your detail window.

HTH,

Sean

On Friday 08 January 2010 16:03:28 franki wrote:
> Hi,
> 
> I have application with main window, which presents some data and when user
> clicks button, new window is opened with more detailed information about
> record that user clicked.
> The problem is, that I can't emit signal from function in this second class
> (that hold more detailed window) to this first class which holds my main
> window. What I'm doing wrong? dumpObjectInfo, also doesn't show this signal
> to be connected to slot in first class.
> Here is a piece of example:
> 
> first class cpp:
> void StackedWidget::startCustPanel(const QModelIndex &index) {
>         custPanelWidget=new custPanel_TabWidget(key,itsql);
> connect(custPanelWidget,SIGNAL(deleteFromMapSig()),this,SLOT(deleteFromMap(
> ))); custPanelWidget->show();
> }
> void StackedWidget::deleteFromMap() {
>         qDebug() << "deleteFromMap started";
> }
> 
> first class header:
> class StackedWidget : public QStackedWidget
> {
>     Q_OBJECT
> public:
>         StackedWidget(QWidget *parent = 0,MainWindow* b = 0);
>         // other variables
>         custPanel_TabWidget *custPanelWidget;
> public slots:
>         //other slots
>         void deleteFromMap();
> private:
>         Ui::StackedWidget sw;
> 
> second class header:
> #ifndef CUSTPANEL_H
> #define CUSTPANEL_H
> #include "ui_custpanel.h"
> #include "itsql.h"
> #include <QObject>
> #include <QTabWidget>
> 
> class StackedWidget;
> 
> class custPanel_TabWidget: public QTabWidget
> {
>         Q_OBJECT
> public:
>         custPanel_TabWidget (QVariant c_id,ItSql *it);
>         ~custPanel_TabWidget();
> public slots:
>         void getCustData();
> signals:
>         void deleteFromMapSig();
> private:
>         Ui::custPanel_TabWidget cp;
>         ItSql *itsql;
>         QVariant cust_id;
> };
> #endif
> 
> second class cpp:
> #include <QtGui>
> #include "custpanel.h"
> 
> custPanel_TabWidget::custPanel_TabWidget(QVariant c_id,ItSql *it) :
> QTabWidget()
> {
>         cp.setupUi(this);
>         emit deleteFromMapSig();
>         this->dumpObjectInfo();
> }
> 
> and output from dumpObjectInfo:
> OBJECT custPanel_TabWidget::custPanel_TabWidget
>   SIGNALS OUT
>         <None>
>   SIGNALS IN
>           <-- QStackedWidget::qt_tabwidget_stackedwidget widgetRemoved(int)
>           <-- QTabBar::qt_tabwidget_tabbar currentChanged(int)
>           <-- QTabBar::qt_tabwidget_tabbar tabMoved(int,int)
> 
> Thanks in advance.
> Marek
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