Zoom effect by mouse Wheel in QGraphicsview

[Santosh Reddy]

having the scene rect bigger thatn view rect shuold make the Zoom effect work as expected, is there any thing else you are missing.

Other Tools: You can use a normal QWidget and implement paintevent, but you will need to handle zoom effect while painting (will not be as stright forward as in case of QGraphicsView).

[chirudi]

i have all done . but the zoom from mouse pointer is not done, zoom is doing to qgraphics view only

[Santosh Reddy]

See if this workaround works, add a QGraphicsRectItem, and set the QGraphicsRectItem rect larger than the screen (monitor) size

[alexvista1234]

you can find the solution in this form

http://www.qtcentre.org/wiki/index.p...ng_and_Zooming


I used it in my code like this :

//in header file
 
protected:
    virtual void wheelEvent(QWheelEvent* event);
 
//in cpp file
void Dialog::wheelEvent(QWheelEvent *event){
 
        ui->graphicsView->setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
        // Scale the view / do the zoom
        double scaleFactor = 1.15;
        if(event->delta() > 0) {
            // Zoom in
            ui->graphicsView-> scale(scaleFactor, scaleFactor);
 
        } else {
            // Zooming out
             ui->graphicsView->scale(1.0 / scaleFactor, 1.0 / scaleFactor);
        }
 
 
        //ui->graphicsView->setTransform(QTransform(h11, h12, h21, h22, 0, 0));
}

//in header file

protected:
    virtual void wheelEvent(QWheelEvent* event);

//in cpp file
void Dialog::wheelEvent(QWheelEvent *event){

        ui->graphicsView->setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
        // Scale the view / do the zoom
        double scaleFactor = 1.15;
        if(event->delta() > 0) {
            // Zoom in
            ui->graphicsView-> scale(scaleFactor, scaleFactor);

        } else {
            // Zooming out
             ui->graphicsView->scale(1.0 / scaleFactor, 1.0 / scaleFactor);
        }


        //ui->graphicsView->setTransform(QTransform(h11, h12, h21, h22, 0, 0));
}

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