Qt – top level widget with keyboard and mouse event transparency

desktop applicationevent handlingqt

I want an app's main window to ignore mouse and keyboard events, passing them to applications underneath it in the window manager Z-order.

I see how to make child widgets ignore keyboard or mouse events, but how about the main window?

I'm trying to make a desktop widget that always sits just over the background and is totally invisible to keyboard and mouse events. (Pass through)

Qt::X11BypassWindowManagerHint gets me keyboard pass through (although sadly X11 specific, but fine for now), so how about mouse events?

Is there a OS-agnostic way to be transparent to keyboard events?

EDIT:

The key word here is transparency.

I don't want to EAT mouse and keyboard events, I want the window manager to know I don't want them at all. Those events should be directed to whatever application is under me in the zorder.

For example, I want to be able to click on desktop icons that are covered by my widget and interact with them as if the widget was not there.

Best Answer

I found the following solution (tested on Linux, also works on Windows according to @TheSHEEEP):

setWindowFlags(windowFlags() | Qt::WindowTransparentForInput);

It has been added in more recent qt release (i did not find when) see http://doc.qt.io/qt-5/qt.html

Related Solutions

Javascript – How to debug JavaScript / jQuery event bindings with Firebug or similar tools

See How to find event listeners on a DOM node.

In a nutshell, assuming at some point an event handler is attached to your element (eg): $('#foo').click(function() { console.log('clicked!') });

You inspect it like so:

jQuery 1.3.x

var clickEvents = $('#foo').data("events").click;
jQuery.each(clickEvents, function(key, value) {
  console.log(value) // prints "function() { console.log('clicked!') }"
})

jQuery 1.4.x

var clickEvents = $('#foo').data("events").click;
jQuery.each(clickEvents, function(key, handlerObj) {
  console.log(handlerObj.handler) // prints "function() { console.log('clicked!') }"
})

See jQuery.fn.data (where jQuery stores your handler internally).

jQuery 1.8.x

var clickEvents = $._data($('#foo')[0], "events").click;
jQuery.each(clickEvents, function(key, handlerObj) {
  console.log(handlerObj.handler) // prints "function() { console.log('clicked!') }"
})

Qt – Keyboard- and mouse-events transparent widget

Here is the sample code which enables me to do drawing on and still mouse events go through it.

Sample::Sample(QWidget *pParent):QWidget(pParent)
{
    setAttribute(Qt::WA_TranslucentBackground);
    setAttribute(Qt::WA_TransparentForMouseEvents);
    setWindowFlags(Qt::FramelessWindowHint);
    QDesktopWidget qDesktopWidget;
    QRect screenSize = qDesktopWidget.screenGeometry();
    setGeometry(screenSize);
}

Sample::~Sample()
{
}

void Sample::paintEvent(QPaintEvent*)
{
    QDesktopWidget new QDesktopWidget();
    QRect rectangle = qDesktopWidget->screenGeometry();
    setGeometry(rectangle);

    const QPoint points[5] = {
        QPoint(0, 20),
        QPoint(rectangle.width(), 20),
        QPoint(rectangle.width(), rectangle.height()),
        QPoint(0,rectangle.height()),
        QPoint(0, 0)
    };

    QPen pen(Qt::blue, 10, Qt::SolidLine, Qt::SquareCap);
    QPainter painter(this);
    painter.setPen(pen);
    painter.drawPolyline(points, 5);
    painter.end();
}

Best Answer

Related Solutions

Javascript – How to debug JavaScript / jQuery event bindings with Firebug or similar tools

Qt – Keyboard- and mouse-events transparent widget

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