Qt Run Single Application - c++

I have a few dialogs and buttons that call these dialogs. However, every click on the button calls a new dialog window. I want the existing window to close first before the user can click on the button to open another.
Below is an example of a button calling a slot. Whenever I click on the button, it will call a copy of the dialog window. Is there any way to only call one copy of the dialog window only?
Thanks.
Bookmark.cpp:
Bookmark::Bookmark()
{
createButtons();
connect(bookmarkButton, SIGNAL(clicked()), this, SLOT(openBookmarkDlg()));
}
void Bookmark::createButtons()
{
...
bookmarkButton = new QToolButton;
bookmarkButton->setText("Bookmark");
addWidget(bookmarkButton);
...
}
void Bookmark::openBookmarkDlg()
{
BookmarkDlg *bkDlg = new BookmarkDlg;
bkDlg->show();
}
Bookmark.h:
class Bookmark : public QToolBar
{
Q_OBJECT
public:
Bookmark(void);
~Bookmark(void);
public slots:
void openBookmarkDlg();
private:
createButtons();
QToolButton *bookmarkButton;
};

If you want the dialog window to be modal, i.e. the application doesn't accept user input outside the dialog, use the window modality of the dialog.
Beware however that modal windows can be really annoying to users.

If BookmarkDlg inherits QDialog you can do the following:
void Bookmark::openBookmarkDlg()
{
BookmarkDlg *bkDlg = new BookmarkDlg;
prepareYourDialog(bkDlg);
/*If you expect to do something when the dialog is accepted*/
if (bkDlg->exec() == QDialog::Accepted)
{
/*Do something after dialog was accepted, and nothing when canceled*/
}
delete bkDlg;
}

Convert BookmarkDlg *bkDlg into a variable member of the class, instead of a local variable of the method:
private:
createButtons();
QToolButton *bookmarkButton;
BookmarkDlg *bkDlg;
Then on the implementation of the class, you could do:
void Bookmark::openBookmarkDlg()
{
if (!bkDlg)
bkDlg = new BookmarkDlg;
bkDlg->show();
}

Related

Qt: Pass QGraphicsSceneContextMenuEvent from QGraphicsView

I have derived from both QGraphicsView and QGraphicsRectItem. I overloaded the contextMenuEvent on both classes to provide popup menus. I want the QGraphicsView context menu when you click on white space the the QGraphicsItem popup menu when you click on an item.
At first implementation, I got the QGraphicsView popup no matter where I clicked. So I modified the contextMenuEvent as follows:
void CustomGraphicsView::contextMenuEvent(QContextMenuEvent* event)
{
if (QGraphicsItem *item = itemAt(event->pos())) {
MyRect* rect = dynamic_cast<MyRect*>(item);
QGraphicsSceneContextMenuEvent* context_event = dynamic_cast<QGraphicsSceneContextMenuEvent*>(event);
if (rect && context_event)
rect->contextMenuEvent(context_event);
}
else {
QMenu menu;
... create the QGraphicsView popup menu
}
}
The dynamic_cast for the QGraphicsSceneContextMenuEvent fails so I never call the contextMenuEvent for the rect. It won't compile if I just try to pass the event to the rect->contextMenu(), so I tried the cast.
What is the right way to do this?
This is a learning project to just create/move/rotate/delete 2D shapes using Qt. If someone wants to look at the whole thing, let me know.
OK, so I figured it out. Just make sure to pass the event through the base class method. Simple! This also works for the mousePressEvent(), mouseMoveEvent(), and mouseReleaseEvent functions.
void CustomGraphicsView::contextMenuEvent(QContextMenuEvent* event)
{
// if the event is on a GGraphicsItem just pass the event along
if (itemAt(event->pos())) {
QGraphicsView::contextMenuEvent(event);
}
else
{
QMenu menu;
... create popup for the CustomGraphicsView

Working with two user interfaces - Qt 5.5

I have a simple MainWindow which has a button and an LineEdit. When I type something and click a button, a new Dialog appears with a label that is supposed to display the string I typed.
So basically, I have trouble sending information to another UI.
I tried working with the new class with a string variable, but it didn't work.
I will try to give an example of what I want to do.
//ui2 Dialog
ui2->label->setText(ui->LineEdit->text());
Ui is a an private variable, so it's not accessible from another class.
//mainwindow.cpp
MainWindow::MainWindow(QWidget*){
this->_dialog = new Dialog(this);
//...
}
MainWindow::on_pushButton_clicked(){
_dialog->_labe->setText(ui->lineEdit->text());
}
//dialog.h
class Dialog{
public:
QLabel* _label;
Dialog(QWidget* ){
_label = ui->label;
}
}

Show/Hide of QMenu

I created the Start Menu by inheriting QMenu. I want to show and hide it using QPropertyAnimation in sliding style
Problem:
Show & hide are working fine when I call them explicitly(on click of start button). But when I click outside of start menu it hides instantly. Please suggest me what could be cause behind this:
My class is StartMenuUiClass which inherited from QMenu
mptrobj_animation is QPropertyAnimation object
void StartMenuUiClass::show()
{
this->raise();
disconnect(mptrobj_animation,SIGNAL(finished()),this,SLOT(this_hide()));
QMenu::show();
mptrobj_animation->setDuration(500);
mptrobj_animation->setStartValue(*mptrobj_startPosition);
mptrobj_animation->setEndValue(*mptrobj_endPosition);
mptrobj_animation->start();
}
void StartMenuUiClass::hide()
{
mptrobj_animation->setDuration(450);
mptrobj_animation->setStartValue(*mptrobj_endPosition);
mptrobj_animation->setEndValue(*mptrobj_startPosition);
connect(mptrobj_animation,SIGNAL(finished()),this,SLOT(this_hide()));
mptrobj_animation->start();
}
void StartMenuUiClass::this_hide()
{
this->lower();
emit work_Done();
QMenu::hide();
}
I think, if you click outside of your menu widget, it simply hides or closes without involving your StartMenuUiClass::hide() function. You can try to handle QMenu::hideEvent(QHideEvent *event) and/or QWidget::closeEvent(QCloseEvent *event). Something like this:
StartMenuUiClass::closeEvent(QCloseEvent *event) // the same for hideEvent()
{
this->hide();
event->accept();
}

QDialog exec() and getting result value

I have subclassed QDialog to implement functionality similar to QMessageBox ( I needed this to allow for customization). It has a text message and OK, Cancel buttons. I am showing the dialog using exec() to make it blocking. Now, how do I return values of true/false when the user clicks on OK/Cancel?
I tried connecting the buttons to setResult() and then, return the result value when clicked, but
Clicking the buttons does not close the dialog box
the return value is incorrect.
Following is the code I have written. I think I am wrong in the exec/result part - but I am not sure how to fix it.
class MyMessageBox : public QDialog {
Q_OBJECT
private slots:
void onOKButtonClicked() { this->setResult(QDialog::Accepted); }
void onCancelButtonClicked() { this->setResult(QDialog::Rejected); }
public:
MyMessageBox(QMessageBox::Icon icon, const QString& title,
const QString& text, bool showCancelButton = true,
QWidget* parent = 0);
virtual void resizeEvent(QResizeEvent* e);
QDialog::DialogCode showYourself()
{
this->setWindowModality(Qt::ApplicationModal);
this->exec();
return static_cast<QDialog::DialogCode>(this->result());
}
};
The user will instantiate the class and call showYourself() which is expected to return the value and also close(and delete) the dialog.
I have posted partial code. Let me know if you need more and I will post the complete version.
Some points :
Rather than using setResult() yourself, use QDialog::accept() and QDialog::reject().
It seems you are not taking full advantage of the signals and slots. You need the object which create the dialog (or another one) to listen to the signals of the dialog.
In your code you are not connecting signals to slots either.
With my fix onOKButtonClicked and onCancelButtonClicked are unnecessary.
With my fix you don't need showYourself(). Just call exec and with the events
information will flow.
You need to add this code before showing the dialog (this assume it is in a dialog method):
QObject::connect(acceptButton, SIGNAL(clicked()), this, SLOT(accept()));
QObject::connect(rejectButton, SIGNAL(clicked()), this, SLOT(reject()));
In the caller object you have
void someInitFunctionOrConstructor(){
QObject::connect(mydialog, SIGNAL(finished (int)), this, SLOT(dialogIsFinished(int)));
}
void dialogIsFinished(int){ //this is a slot
if(result == QDialog::Accepted){
//do something
return
}
//do another thing
}
Another solution:
// set signal and slot for "Buttons"
connect(YesButton, SIGNAL(clicked()), dlg, SLOT(accept()));
connect(NoButton, SIGNAL(clicked()), dlg, SLOT(reject()));
// show modal window event loop and wait for button clicks
int dialogCode = dlg->exec();
// act on dialog return code
if(dialogCode == QDialog::Accepted) { // YesButton clicked }
if(dialogCode == QDialog::Rejected) { // NoButton clicked }
Case 1 Clicking the buttons does not close the dialog box.
For this you have to close the dialog on respective SLOTS, so Use
void onOKButtonClicked(){ this->setResult(QDialog::Accepted); this->close();}
void onCancelButtonClicked(){ this->setResult(QDialog::Rejected);this->close();}
Note: Only after you have clicked the Ok button or Cancel button in a standard QMessageBox, setResult() function is triggered and the status is changed. It's not the same effect when done vice versa.
Case 2 The return value is incorrect.
I think only after your dialog gets closed, you will have the result available in result() function. So I guess it will be solved, after you have made the changes specified in Case 1.
If it still persists, use your own private member function to resolve it.

Open only one instance of QDialog with show() , and also does the Object is deleted if i close the QDialog

in Qt im opening QDialog windows each time i click some item
im doing it with new , i like to be sure im opening only one instance of QDialog for each item
im clicking :
void foo::treeWidget_itemClicked(QTreeWidgetItem *item,nt column)
.....
QString groupID = item->data(0, Qt::UserRole).toString();
QString groupName = item->text(0);
GroupDialogContainer* pGroupDialogContainer = new GroupDialogContainer(groupID, groupName, this);
pGroupDialogContainer->show();
}
class GroupDialogContainer : public QDialog
{
Q_OBJECT
public:
GroupDialogContainer(QString GroupId,QString GroupName,QWidget *parent=0);
GroupDialogContainer(QWidget *parent=0);
virtual ~GroupDialogContainer();
Ui::GroupDialog ui;
public slots:
void closeEvent(QCloseEvent *event);
};
do i need to keep some kind of hash or vector of GroupDialogContainer ?
also my second question is :
does each time im closing the QDialog window with close () the object pGroupDialogContainer
that was responsible to open it is destroyer ed ? or do i need to delete it when im detecting that the QDIalog has closed?
Yes, you should probably keep some kind of list of your dialogs to keep track of which ones are already open. If your GroupID is your unique ID then you could do something like this:
QMap DialogMap;
void foo::treeWidget_itemClicked(QTreeWidgetItem *item,nt column)
{
.....
QString groupID = item->data(0, Qt::UserRole).toString();
if (! DialogMap.contains(groupID))
{
// Popup the dialog and add it to map
...
DialogMap.insert(groupID, pGroupDialogContainer);
}
}
Now, for the other part. The most important thing is that you need to remove the item from the map when the dialog closes. You could either delete the dialog then, or my suggestion would be to let the dialog delete itself when it closes - as follows:
// set automatic deletion of object on close
setAttribute(Qt::WA_DeleteOnClose);
But as I said, you'll still need to remove the dialog from the Map, or else you'll have a bad pointer in there, and your code will still think the dialog is open.
So you'll need some kind of signal from the dialog to indicate that it is closing. There is the finished(int result) signal, that is called when you trigger a result:
This signal is emitted when the
dialog's result code has been set,
either by the user or by calling
done(), accept(), or reject().
But, you can always create your own signal in your dialog, and emit it when the closeEvent is called in your dialog.
Then in the code that handles the map...
connect( pGroupDialogContainer, SIGNAL(WindowClosed()), this, SLOT(vCleanUpTheMap()));
...
void vCleanUpTheMap()
{
GroupDialogContainer *pDialog = dynamic_cast<GroupDialogContainer *>(sender());
if (pDialog)
{
// Just to keep things clean disconnect from the dialog.
disconnect(pDialog);
// I am assuming that you can get the key groupID from the dialog
// Cause it's a lot easier to remove from a map with the key
DialogMap.remove(pDialog->GetGroupID());
}
}
And that's it.