[Qt-interest] ugly QGraphicsTexItem when it is zoomed

[Constantin Makshin]

I suggest you to use QGraphicsView::setTransform().

As an example of zooming feature, here is the related code from my application (FlowchartView is a subclass of QGraphicsView):

void FlowchartView::setScale (qreal scale)
{
    // Get the point the view is currently centered at
    QPointF viewCenter = mapToScene(rect().center());

    // Scale the view
    setTransform(QTransform::fromScale(scale, scale));

    // Restore old view position
    centerOn(viewCenter);
}

void FlowchartView::setScale (int percentage)
{
    setScale(qreal(percentage) / 100.0f);
}

On Friday 17 September 2010 06:14:10 changwon lee wrote:
>   thank you for answer.
> 
> but I zoomed view by view api like this.
> 
> void MainWindow::sceneScaleChanged(const QString &scale)
> {
>      //double newScale = scale.left(scale.indexOf(tr("%"))).toDouble() / 
> 100.0; //I have modified original source code. to use any scale factor.
>      double newScale = scale.toDouble();
>      QMatrix oldMatrix = view->matrix();
>      view->resetMatrix();
>      view->translate(oldMatrix.dx(), oldMatrix.dy());
>      view->scale(newScale, newScale);
> }
> 
> just added QGraphicsTextItem (font size1.5) to scene
> and scaled using above code.
> 
> is this method wrong? (this is example of Qt)
> 
> regards
> 
> On 2010-09-17 오전 5:00, Jason H wrote:
> > Agreed. Don't handle zoom yourself, let Qt do that.
> >
> >
> >
> >
> > ----- Original Message ----
> > From: Constantin Makshin<cmakshin at gmail.com>
> > To: Qt Interest<qt-interest at trolltech.com>
> > Sent: Thu, September 16, 2010 2:17:25 PM
> > Subject: Re: [Qt-interest] ugly QGraphicsTexItem when it is zoomed
> >
> > Have you tried QGraphicsTextItem::setTextWidth()?
> >
> > And don't scale/zoom by doing everything (move and resize items, etc.) yourself
> > — you're likely to get better results by using QGraphicsView::setTransform().
> >
> > On Thursday 16 September 2010 18:37:11 changwon lee wrote:
> >>    Hello
> >>
> >> I have attached two pictures.
> >> These are the result of modified DiagramScene Example.
> >>
> >> I have modified two part.
> >> one is font size and another is scale;
> >> I used float font size and can change scale freely.
> >>
> >> change_font_size_fix_scale image looks good.
> >> it's font size is 48.5 and no scale is applied.
> >>
> >> fix_font_size_change_scale image looks bad.
> >> I have set font size 1.5 and magnified x37.
> >>
> >> I want to define font size as scene coordinate. if I change scale, text
> >> changes with other objects in scene.
> >> This is similar to adding text in CAD. User define text size as length
> >> in drawing coordinate system.
> >> but it seems that my assumption is not true.
> >>
> >> Do I have to change font size when scale changes?
> >>
> >> regards