I am trying to set a tool tip for QRubberBand. This is how the constructor of the parent looks. Please note the parent is not a window, but rather a widget of a window.

    roiRB = new QRubberBand( QRubberBand::Rectangle,this);
    roiRB->setGeometry(QRect(QPoint(1,1), QPoint(100,100)));

    roiRB->setAttribute(Qt::WA_AlwaysShowToolTips); //I tried this line as mentioned in the Documentation to all parent classes of the QRubberBand.
    roiRB->setToolTip("Hello");
    roiRB->setToolTipDuration(1000);

However the tooltip is not popping, I tried different values for toolTipDuration as well.

CodePudding user response：

If you look at the documentation, you can read:

Note that by default tooltips are only shown for widgets that are children of the active window. You can change this behavior by setting the attribute Qt::WA_AlwaysShowToolTips on the window, not on the widget with the tooltip.

^{emphasis mine}

You have set the attribute Qt::WA_AlwaysShowToolTips on the widget with the tooltip and not on the window itself which is exactly the opposite of what is mentioned in the documentation.

CodePudding user response：

On digging the source code of QRubberBand, I found out that in the constructor of QRubberBand, the attribute (Qt::WA_TransparentForMouseEvents); is set to true. Manually setting this back to false fixed the issue.

From what I see, tooltips work on MouseEvent calls of the widget, if the this attribute is set to true, the widget ignores MouseEvents and thereby nullifying the setToolTip("abcd").

Therefore,

roiRB = new QRubberBand( QRubberBand::Rectangle,this);
roiRB->setAttribute(Qt::WA_TransparentForMouseEvents,0);

is all you need to do. Do let me know if I have missed something.