Qt GraphicsScene背景不变

Question

i am a newbie to Qt.i am handling canvas widgets through QGraphicsScene class.But i cant change the default white background of the widget.Here is the code.i have tried to use the QBrush to set the background.But it did not work.it remains white.what is the problem in the following code?

int main(int argc, char **argv){

    QApplication a(argc, argv);


    QGraphicsScene canvas;
    canvas.addText("Hello World");
    QColor *color=new QColor(0x70,0x80,0x50,255);
    QBrush *brush=new QBrush();
    brush->setColor(*color);
    canvas.setBackgroundBrush(*brush);

    QGraphicsView view(&canvas);
    view.show();




    return a.exec();


}

Answer 1

Try passing the color into the brush constructor instead of afterwards

QBrush brush(QColor(0x70, 0x80, 0x50, 255));
canvas.setBackgroundBrush(brush);

Which will set the brush style to Qt::SolidPattern . The default brush constructor sets the style to Qt::NoBrush . See http://qt-project.org/doc/qt-4.8/qbrush.html#QBrush

Answer 2

view.setStyleSheet("background-color: black;");