How to change the color of the text of a QProgress

问题:

I don't know how to change the color of the text partially in the progress bar when its value becomes nearly 50%. This effect comes automatically in the fusion style progress bar (picture below). Does anyone know how this is done ?

回答1:

Too lazy to write working example code, much less making a screenshot. Not even for 50 reps. :-)

However, the question was somewhat interesting. I had no idea how such a two colored text could be done. So I checked: http://qt.gitorious.org/qt/qtbase/blobs/stable/src/widgets/styles/qfusionstyle.cpp Line 1450ff (http://qt.gitorious.org/qt/qtbase/blobs/stable/src/widgets/styles/qfusionstyle.cpp#line1450).

    QRegion rightRect = rect;
    rightRect = rightRect.subtracted(leftRect);
    painter->setClipRegion(rightRect);
    painter->setPen(flip ? alternateTextColor : textColor);
    painter->drawText(rect,
                      bar->text,
                      QTextOption(Qt::AlignAbsolute|
                                   Qt::AlignHCenter|
                                   Qt::AlignVCenter));
    if (!leftRect.isNull()) 
    {
        painter->setPen(flip ? textColor : alternateTextColor);
        painter->setClipRect(leftRect);
        painter->drawText(rect,
                 bar->text,
                 QTextOption(Qt::AlignAbsolute|
                              Qt::AlignHCenter|
                              Qt::AlignVCenter));
    }

Basically the text is drawn two times into the same rectangle. Each time with an appropriate clipping. Easy if you know how. :-)

回答2:

From my point of view the best, and probably the easiest, way to do this is to change the pallet for the QProgressBar widget:

    QPalette palette = progressBar->palette()
    palette.setColor(QPalette::Text, textColor)
    palette.setColor(QPalette::HighlightedText, textColor)
    progressBar->setPalette(palette)

回答3:

You can use stylesheet on the Container Widget :

myMainWidget.setStyleSheet(QString("QProgressBar {color: red}"));