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invalid conversion from ‘QEvent*’ to ‘QPaintEvent*’

开发者 https://www.devze.com 2023-03-12 18:55 出处:网络
trying to find if touch event occurs or else just paint them. bool MyWidget::event(QEvent *event) { switch (event->type())

trying to find if touch event occurs or else just paint them.


bool MyWidget::event(QEvent *event)
{
    switch (event->type())
    {
            case QEvent::TouchBegin:
            case QEvent::TouchUpdate:
            case QEvent::TouchEnd: 
        {

            QTouchEvent *touchEvent = static_cast(event);

            if (touchEvent->touchPoints().count() == 2) 
            {
                const QTouchEvent::TouchPoint &touchPoint1 = touchEvent->touchPoints().first();
                const QTouchEvent::TouchPoint &touchPoint2 = touchEvent->touchPoints().last();
                nx=touchPoint1.scenePos().x();
                ny=touchPoint1.scenePos().y();
                pix = QPixmap::grabWidget (this,nx,ny,1,1);
                img = pix.toImage();
                rgb = img.pixel(0,0);
                color.setRgb(rgb);
                drawBit=1;
            }
        break;
         }

            case QEvent::Paint:

                  return MyWidget::paintEvent( event);  
              break;

         default:
            return false;
            break;
    }

     return true;
}



void MyWidget::paintEvent(QPaintEvent *event)
{

time_counter++;
for(i=0;(ired,b[i]->green,b[i]->blue,255), Qt::SolidPattern));
painter开发者_StackOverflow.drawEllipse(b[i]->x,b[i]->y,b[i]->w, b[i]->w);
painter.drawLine(b[i]->x+b[i]->w/2,b[i]->y+b[i]->w,b[i]->x+b[i]->w/2,b[i]->y+2*b[i]->w);

if(b[i]->ballDead==false)
b[i]->y+=b[i]->vy;

if(drawBit==1 && b[i]->red==color.red() && b[i]->green==color.green() && b[i]->blue==color.blue())
ballHit(i);


}
}



this code shows error like:
mywidget.cpp:116:47: error: invalid conversion from ‘QEvent*’ to ‘QPaintEvent*’
mywidget.cpp:116:47: error:   initializing argument 1 of ‘virtual void MyWidget::paintEvent(QPaintEvent*)’
mywidget.cpp:116:47: error: void value not ignored as it ought to be


If you want to call paintEvent, you'll need to cast the QEvent*, something like:

paintEvent(static_cast<QPaintEvent*>(event));
return true;

But as others have said, don't come complaining if you find yourself in an endless repaint loop or with an otherwise stuck event loop.

If you want a periodic repaint, set up a QTimer and have it call you widget's update() slot.


Its not a good practice to call paintEvent() directly.Call repaint() or update() instead.Those methods will then call paintEvent() with the right parameter.

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