Qtreeview MouseEvent

Shiv

Dear All
I have implemented a QTreeview with QAbstractItemModel now I want to emit a signal whenever mouse is clicked with LeftButton on the Items of the QTreeview.I have tried with 'clicked' and 'selectionChanged' signal but the problem is it responds for RightButton too since I have to use a context menu for RightClick . Is there any way to emit a signal from QTreeview other than QEvent eventfilter or QMouseEvent.
Thanks

mrjj

hi
Im not 100% sure what is not working except right click should not
give "selectionChanged" for your use case ?

If you already have a QTreeview child with a
mousePressEvent(QMouseEvent *event)
implemented you could just make your own signal?

treeview..
public signals:
void LeftClicked( any param u want );

then in mousePressEvent
if (event->button() == Qt::LeftButton) {
emit LeftClicked( the actual paramters);
}

Then from outside u just use your new signal.

Note: for a signal, you do not implement anything in the cpp. its
just a definition in the class. No body.

Shiv

Hi @mrjj Thanks for your kind reply
Implementing through QMouseEvent is not an issue . I thought if any signal like 'clicked' is already available I can start using it directly.

Thank you

mrjj

@Shiv
well yes, you could also emit clicked.

do you use
http://doc.qt.io/qt-5/qcontextmenuevent.html#details

to make the context menu ?

Shiv

@mrjj
No I am not using QContextMenuEvent just implementing with ActionsContextMenu policy and adding actions to the treeview.In my case if I use 'clicked' signal implementing context menu is difficult .

mrjj

Ok.
But catching MousePress and check
if left button then emit
new signal for left selection
and if not left button,
then simply call base class MousePress
Is not acceptable for you?

Shiv

@mrjj
I will try and let you know

Thanks

Shiv

Hi @mrjj
I have tried to implement mouse press event with event filters using below code

ui.usertreeView->installEventFilter( this );  //event filter for qtreeview

//event handler
bool MainWindow::eventFilter( QObject * watched, QEvent * event )
{
   QTreeView *view = qobject_cast<QTreeView *>(watched);

   QMouseEvent *k = (QMouseEvent *)event;
   
   if(watched==view)
   {
   	if((k->button())== Qt::LeftButton)
   	{
   		qDebug()<<"treeview event";
   	}
   }

   return QObject::eventFilter(watched, event);
}

but no event is getting generated when I click on the treeview.

If the same code is used to capture for a QLabel the event is getting generated.What may be the reason?

Thanks

mrjj

Hi
No, that sounds odd. Should also work for
treeview.
Is there a reason to use a eventfilter versus
just implement the MousePress function ?

Shiv

Hi @mrjj

Its not working for treeview .There are lot of widgets in my application to segregate the mouse press event i have used event filter.But i am unable to understand why the event filter is not working for treeview if possible can you check at your end .

Thanks

mrjj

@Shiv
Hi
Why not just override
mousePressEvent(QMouseEvent *event)
for treeview?
I dont understand why you try with eventfilter even i completely agree
all events should also be seen there.
I will try eventfilter on tree and see if I get a hint.

mrjj

hi
The Tree have a viewport that get these events
so
ui->listView->viewport()->installEventFilter(this);

and

bool MainWindow::eventFilter( QObject* watched, QEvent* event ) {
  qDebug() << "treeview event !1";
  QTreeView* view = qobject_cast<QTreeView*>(watched);

  QMouseEvent* k = static_cast<QMouseEvent*>(event);

  if(k) {
    if((k->button()) == Qt::LeftButton) {
      qDebug() << "treeview button down 3 ";
    }
  }

worked for me.

return QObject::eventFilter(watched, event);
}

Shiv

Hi @mjrr
Thanks for your valuable time and code.
Its working fine with this code.The event is working fine in QT5.4 but I am currently doing this project in Qt 4.8.4 with VS2008 there some spurious events are getting generated without pressing the mouse.I am unable find the cause for this peculiar behavior. Any solution/idea will be helpful for me to move forward.

Thanks

mrjj

@Shiv
Hi, ok that is good to hear.
Very hard to guess at when its other Qt and compiler :)

You can use my event debug function
http://paste.ofcode.org/xKREBjyuFwX6FEzTr4rRAP

and call it with
qDebug() << "EVENT: " << event->type() << " = " << EventDesc(event->type() );
in the event filter to see if u can guess what is happening.

Shiv

@mjrr
I will try and let you know.
Thanks

Shiv

Hi @mjrr
I have tried with your EventDesc function the mouse press event automatically getting generating and it happens randomly I know its difficult to replicate this issue at your end i am posting some of the debug message kindly have look.The BTN variable is the mouseevent k->button() value

//BTN k->button() value
EVENT:  127  =   mouse cursor enters a hover widget 

EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  2 
EVENT:  12  =   paint widget 
BTN  2347008 
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  2 
EVENT:  129  =   mouse cursor move inside a hover widget 
//BTN  1  // mouse event without mouse action
//treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
//BTN  1 
//treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
//BTN  1 
//treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  1 
treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
//BTN  1 
//treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
//BTN  1 
//treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  1 
treeview button down 3  
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  2 
EVENT:  110  =  Tooltip 
BTN  0 
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  1 
treeview button down 3  
EVENT:  110  =  Tooltip 
BTN  0 
EVENT:  129  =   mouse cursor move inside a hover widget 
BTN  0 
EVENT:  129  =   mouse cursor move inside a hover widget

Thank you

mrjj

hi
what about


bool MainWindow::eventFilter( QObject* watched, QEvent* event ) {
  qDebug() << "treeview event !1";
  QTreeView* view = qobject_cast<QTreeView*>(watched);

  QMouseEvent* k = static_cast<QMouseEvent*>(event);

  if(k && k->type() == QEvent::MouseButtonPress) {
    if((k->button()) == Qt::LeftButton) {
      qDebug() << "treeview button down 3 ";
    }
  }
  return QObject::eventFilter(watched, event);
}

Shiv

Hi
Great its working thanks a lot..
Thank you

mrjj

super :)
Error was that we use
<QMouseEvent*>
and Hover is also such type , i think.
No idea why k->button() seems to be set for those but
with extra check it works then :)