[QT3+XP] transparency and mouse tracking

[incapacitant]

hi

The following code has (at least) 2 problems :

// set background and size it correctly
QWidget *main = new QWidget( this );
( this )->resize( 569, 458 );
setPaletteBackgroundPixmap
  ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
 
// track mouse moves
setMouseTracking ( true );
 
// exit push button
QPushButton * pbClose = new QPushButton ( this );
pbClose->resize( QSize( 10, 10 ) ); 
pbClose->move( 551, 5 );  // position over background
pbClose->setMask( QBitmap() ); // for transparency
 
connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

// set background and size it correctly
QWidget *main = new QWidget( this );
( this )->resize( 569, 458 );
setPaletteBackgroundPixmap
  ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
    
// track mouse moves
setMouseTracking ( true );
    
// exit push button
QPushButton * pbClose = new QPushButton ( this );
pbClose->resize( QSize( 10, 10 ) ); 
pbClose->move( 551, 5 );  // position over background
pbClose->setMask( QBitmap() ); // for transparency

connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

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1. setMouseTracking must be wrongly implemented because it never starts the slots,
2. if i include the line "pbClose->setMask( QBitmap() );" then the control is transparent,
but it never signals the click. (w/o this line I can click but the background in not
visible anymore.

I tried various things but none worked, can you help me ?

[high_flyer]

Try:

// set background and size it correctly
QWidget *main = new QWidget( this );
( this )->resize( 569, 458 );
setPaletteBackgroundPixmap
  ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
 
 
// exit push button
QPushButton * pbClose = new QPushButton ( this );
// track mouse moves
pbClose->setMouseTracking ( true );
 
pbClose->resize( QSize( 10, 10 ) ); 
pbClose->move( 551, 5 );  // position over background
pbClose->setMask( QBitmap() ); // for transparency
 
connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

// set background and size it correctly
QWidget *main = new QWidget( this );
( this )->resize( 569, 458 );
setPaletteBackgroundPixmap
  ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
    
    
// exit push button
QPushButton * pbClose = new QPushButton ( this );
// track mouse moves
pbClose->setMouseTracking ( true );

pbClose->resize( QSize( 10, 10 ) ); 
pbClose->move( 551, 5 );  // position over background
pbClose->setMask( QBitmap() ); // for transparency

connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

To copy to clipboard, switch view to plain text mode 

2. if i include the line "pbClose->setMask( QBitmap() );" then the control is transparent,
but it never signals the click. (w/o this line I can click but the background in not
visible anymore.

If you set parts of the widget to be invisible with setMask(), the invisible parts will not react to mouse clicks, only the visible parts.

[incapacitant]

putting

pbClose->setMouseTracking ( true );  // does start the slots !

pbClose->setMouseTracking ( true );  // does start the slots !

To copy to clipboard, switch view to plain text mode 

even when displaying the button.

And anyway how can you have a transparent button that will be possible to click ?
I have not found another way.

[high_flyer]

putting

pbClose->setMouseTracking ( true );  // does start the slots !

pbClose->setMouseTracking ( true );  // does start the slots !

To copy to clipboard, switch view to plain text mode 

even when displaying the button.

Do you have any more signal/slots connection to pbClose beside the ones you show here?

And anyway how can you have a transparent button that will be possible to click ?
I have not found another way.

Is it tottaly transparent, or only opaque to some degree?

[incapacitant]

well, no these are the only slots.
and with

pbClose->setMask( QBitmap() );

pbClose->setMask( QBitmap() );

To copy to clipboard, switch view to plain text mode 

it is 100% invisible (as I would like it)

[high_flyer]

I can't explain why the slots fire on paintEvent.
On the code you provided so far, I can't see an explanation to that behaviour.

But you can't have a "clickable" invisible widget "out of the box" AFAIK, and it is logical to be so, since it makes no sense to have clickable yet invisible controls.
You will have to implement your own style probobly to deal with 100% invisible clickable widgets.

[jacek]

connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );

To copy to clipboard, switch view to plain text mode 

That's not the way to receive events. You must reimplement QWidget::enterEvent() and QWidget::leaveEvent () methods or use event filter.

[high_flyer]

OFCOURSE!!
Bahh... these are events...
I think I need to do something elese for few minites... :-)

[incapacitant]

complete code :

#include <qpixmap.h>
#include <qpushbutton.h>
#include <qbitmap.h>
#include <qcursor.h>
#include <qevent.h>
 
#include "application.h"
 
ApplicationWindow::ApplicationWindow()
    : QMainWindow( 0, "Application", 
                   Qt::WStyle_Customize | 
                   Qt::WStyle_Splash | 
                   WDestructiveClose | 
                   WGroupLeader )
{   
    // set background and size it correctly
    QWidget *main = new QWidget( this );
    ( this )->resize( 569, 458 );
    setPaletteBackgroundPixmap
      ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
 
    // exit push button
    QPushButton * pbClose = new QPushButton ( this );
    // track mouse moves
    pbClose->setMouseTracking ( true );
 
    pbClose->resize( QSize( 10, 10 ) ); 
    pbClose->move( 551, 5 );  // position over background
//    pbClose->setMask( QBitmap() ); // for transparency
 
    connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
    connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
    connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );
}
 
 
//****************************************************************
ApplicationWindow::~ApplicationWindow()
{
}
 
//****************************************************************
void ApplicationWindow::changeCursor()
{
     close();
//  QCursor( 2 ); //QCursor::PointingHandCursor);
    return;
}
 
//****************************************************************
void ApplicationWindow::resetCursor()
{
     close();
    return;
}

#include <qpixmap.h>
#include <qpushbutton.h>
#include <qbitmap.h>
#include <qcursor.h>
#include <qevent.h>

#include "application.h"

ApplicationWindow::ApplicationWindow()
    : QMainWindow( 0, "Application", 
                   Qt::WStyle_Customize | 
                   Qt::WStyle_Splash | 
                   WDestructiveClose | 
                   WGroupLeader )
{   
    // set background and size it correctly
    QWidget *main = new QWidget( this );
    ( this )->resize( 569, 458 );
    setPaletteBackgroundPixmap
      ( QPixmap::fromMimeSource( "images/Exemple_Background.png" ) );
    
    // exit push button
    QPushButton * pbClose = new QPushButton ( this );
    // track mouse moves
    pbClose->setMouseTracking ( true );
    
    pbClose->resize( QSize( 10, 10 ) ); 
    pbClose->move( 551, 5 );  // position over background
//    pbClose->setMask( QBitmap() ); // for transparency

    connect( pbClose, SIGNAL( clicked() ), this, SLOT( close() ) );
    connect( pbClose, SIGNAL( QEvent::Enter ), this, SLOT ( changeCursor() ) );
    connect( pbClose, SIGNAL( QEvent::Leave ), this, SLOT ( resetCursor() ) );
}


//****************************************************************
ApplicationWindow::~ApplicationWindow()
{
}

//****************************************************************
void ApplicationWindow::changeCursor()
{
     close();
//  QCursor( 2 ); //QCursor::PointingHandCursor);
    return;
}

//****************************************************************
void ApplicationWindow::resetCursor()
{
     close();
    return;
}

To copy to clipboard, switch view to plain text mode 

and regarding invisible widgets, you are correct I will have to design them. How ?
I have no clue at this time.

Thanks anyway

[incapacitant]

oops, i had not seen jacek comments. i will try. tx