[SOLVED] Custom drawing of a QSlider (Qt)

Custom drawing of a QSlider (Qt)

I want to intercept the QPaintEvent on a QSlider and draw it. But I can not find the details on the geometry of the thing. I can know the rect() of the whole widget but how can you tell the position of first tickmark or the last one in the widget's rectangle? (there's a margin at left and right of the tracking channel). Or the rectangle of the "handle"?

Solution

Here's a way using QStyleOptionSlider and QStyle:

QStyleOptionSlider opt;
slider->initStyleOption(&opt);
    
QStyle *styl=style();
Rect rectHandle=styl->subControlRect(QStyle::CC_Slider, 
                                     &opt, 
                                     QStyle::SC_SliderHandle, 
                                     NULL);
Rect rectGroove=styl->subControlRect(QStyle::CC_Slider, 
                                     &opt, 
                                     QStyle::SC_SliderGroove, 
                                     NULL);

// width in an horizontal slider of the groove (width of widget - margins)    
int avl=styl->pixelMetric(QStyle::PM_SliderSpaceAvailable, &opt, this);