void MyCanvasView::contentsMousePressEvent(QMouseEvent* e)
{
    Q3CanvasItemList l = canvas()->collisions(e->pos());
    for (Q3CanvasItemList::Iterator it=l.begin(); it!=l.end(); ++it) {
        if ((*it)->rtti() == Q3CanvasRectangle::RTTI)
            qDebug("A Q3CanvasRectangle lies somewhere at this point");
    }
}

QMatrix wm;
wm.scale(2, 2);   // Zooms in by 2 times
wm.rotate(90);    // Rotates 90 degrees counter clockwise
                  // around the origin.
wm.translate(0, -canvas->height());
                  // moves the canvas down so what was visible
                  // before is still visible.
myCanvasView->setWorldMatrix(wm);

QRect rc = QRect(myCanvasView->contentsX(), myCanvasView->contentsY(),
                 myCanvasView->visibleWidth(), myCanvasView->visibleHeight());
QRect canvasRect = myCanvasView->inverseWorldMatrix().mapRect(rc);

Member Function Documentation

Q3CanvasView::Q3CanvasView(QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0)

Constructs a Q3CanvasView with parent parent, and name name, using the widget flags f. The canvas view is not associated with a canvas, so you must to call setCanvas() to view a canvas.

Q3CanvasView::Q3CanvasView(Q3Canvas * canvas, QWidget * parent = 0, const char * name = 0, Qt::WindowFlags f = 0)

This is an overloaded function.

Constructs a Q3CanvasView which views canvas canvas, with parent parent, and name name, using the widget flags f.

Q3CanvasView::~Q3CanvasView()

Destroys the canvas view. The associated canvas is not deleted.

Q3Canvas * Q3CanvasView::canvas() const

Returns a pointer to the canvas which the Q3CanvasView is currently showing.

See also setCanvas().

[virtual protected] void Q3CanvasView::drawContents(QPainter * p, int cx, int cy, int cw, int ch)

Reimplemented from Q3ScrollView::drawContents().

Repaints part of the Q3Canvas that the canvas view is showing starting at cx by cy, with a width of cw and a height of ch using the painter p.

const QMatrix & Q3CanvasView::inverseWorldMatrix() const

Returns a reference to the inverse of the canvas view's current transformation matrix.

See also setWorldMatrix() and worldMatrix().

void Q3CanvasView::setCanvas(Q3Canvas * canvas)

Sets the canvas that the Q3CanvasView is showing to the canvas canvas.

See also canvas().

bool Q3CanvasView::setWorldMatrix(const QMatrix & wm)

Sets the transformation matrix of the Q3CanvasView to wm. The matrix must be invertible (i.e. if you create a world matrix that zooms out by 2 times, then the inverse of this matrix is one that will zoom in by 2 times).

When you use this, you should note that the performance of the Q3CanvasView will decrease considerably.

Returns false if wm is not invertable; otherwise returns true.

See also worldMatrix(), inverseWorldMatrix(), and QMatrix::isInvertible().

[virtual protected] QSize Q3CanvasView::sizeHint() const

Reimplemented from QWidget::sizeHint().

Suggests a size sufficient to view the entire canvas.

const QMatrix & Q3CanvasView::worldMatrix() const

Returns a reference to the canvas view's current transformation matrix.

See also setWorldMatrix() and inverseWorldMatrix().