Best place to apply a QMatrix transform to paint() event in an app

[Caolan O'Domhnaill]

Hello all,

I am working on a mathematics tutor app and so I need to transform my coordinate space into traditional Cartesian Coordinates.

I have found a solution here: http://stackoverflow.com/questions/4...painter-y-axis

which I have added to one of my QGraphicsItem object's paint() event handlers for testing but I would like to apply it at a more global scale. I looked at the widget I am using as the QGraphicsView as the place to set this however it doesn't have a paint(), just these:

virtual void 	drawBackground(QPainter * painter, const QRectF & rect)
virtual void 	drawForeground(QPainter * painter, const QRectF & rect)

virtual void 	drawBackground(QPainter * painter, const QRectF & rect)
virtual void 	drawForeground(QPainter * painter, const QRectF & rect)

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If I wanted to plug the code into my application so that EVERYTHING is drawn automagically in the coordinate system I need it to be, where is the best place to put it?

Code I have added to my QGraphicsItem:

void PhysVector::paint(QPainter *pPainter, const QStyleOptionGraphicsItem *pOption, QWidget *) {
 
    // Setting the matrix rotates the drawing area to be a normal cartesian plane. Unfortunately
    // it also means that the original drawing has to be tweaked
    QMatrix matrix;
    matrix.scale(1, -1);
    pPainter -> setMatrix(matrix);

void PhysVector::paint(QPainter *pPainter, const QStyleOptionGraphicsItem *pOption, QWidget *) {

    // Setting the matrix rotates the drawing area to be a normal cartesian plane. Unfortunately
    // it also means that the original drawing has to be tweaked
    QMatrix matrix;
    matrix.scale(1, -1);
    pPainter -> setMatrix(matrix);

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One further note I would like to make, is I would like to affect ONLY the drawing of objects, not the interaction of mouse clicks and what not. Unless they are inseparable I mean...
Thank you!
- Caolan