CODEWITHSUNDEEP
c++qtqt5qpainterqpixmap
Griffort
Griffort

Reputation: 1305

How to draw darkened QPixmap?

I'm looking for a fast and effective way to draw a QPixmap with QPainter, but have the pixmap appear darker then normal. Is there some sort of filter or effect that can be applied to either the QPixmap or QPainter while drawing to create this effect?

Upvotes: 3

Views: 1495

Answers (2)

Judge Gazza
Judge Gazza

Reputation: 61

Some of the earlier comments will leave a dark gray rectangle on your screen. Using the composition mode, will darken everything visible, yet leaving any transparent areas still transparent.

painter.setCompositionMode (QPainter::CompositionMode_DestinationIn);
painter.fillRect (rect, QBrush (QColor (0,0,0,128)));

Upvotes: 2

dtech
dtech

Reputation: 49329

You don't have pixel access in QPixmap, so going over the pixels and darkening them is out of the question.

You can however fill a pixmap with a transparent black brush, and use a number of composition modes to further customize the result.

    QPainter painter(this);
    QPixmap pm("d:/test.jpg");
    painter.drawPixmap(QRect(0, 0, 400, 200), pm);
    painter.translate(0, 200);
    painter.drawPixmap(QRect(0, 0, 400, 200), pm);
    painter.fillRect(QRect(0, 0, 400, 200), QBrush(QColor(0, 0, 0, 200)));

enter image description here

Upvotes: 6

Related Questions