Change in the geometry of item on changing parent

[djasmine]

Say I have an item A which is child of a parent P1.
Now I rotate item A by 180.
I have another item P2 which is rotated by 90 and horizontally mirrored.
Now when I try to make P2 as parent of item A, it's position, rotation and mirroring gets completely modified.

I am able to fix the position of item by adjusting it based on its scene position.
But I am unable to get its original transformations (rotate/mirror) back.
How can I resolve this??
Also is there any way to modify the scene transformation of any item ??

[SGaist]

Hi,

Can you share the related code ?

[djasmine]

/* Below I am sharing a minimal stand alone code simulating the problem shared above, its not the actual code from my project */

QGraphicsView graphicsView;
QGraphicsScene *scene = new QGraphicsScene(&graphicsView);
graphicsView.setScene(scene);

QGraphicsRectItem * parent1 = new QGraphicsRectItem();
parent1 ->setRect(QRectF(-100, -50, 200, 100);
parent1->setPos(100, 100);
scene->addItem(parent1 );

QGraphicsRectItem * parent2 = new QGraphicsRectItem();
parent2 ->setRect(QRectF(-100, -50, 200, 100);
parent2->setPos(250, 250);
scene->addItem(parent2 );

//parent1 being set as parent of text
QGraphicsSimpleTextItem * text = new QGraphicsSimpleTextItem();
text->setText("I am Text");
text->setParentItem(parent1);
text->setPos(QPointF(0,0));

//rotate parent2 by 90 and then make it as parent of text
QTransform tr;
tr.rotate(90);
parent2->setTransform(tr);
text->setParentItem(parent2);

Now text will jump to another position along with some rotation applied (inherited from parent).
I am to handle to jump in position as below:

QPointF oldPos = text->mapToScene(pos()); //fetch scene pos before setting parent2
QPointF newPos = text->maptoScene(pos()); // fetch pos after setting parent2

text->setPos( pos() + (oldPos - newPos) );

Now text stays where it was created but rotates.
How to stop rotation?
I know there is a flag itemIgnoresTransformation.
In our case there is a hierarchy of parents and some view transformations like zoom which we want to get automatically passed on to all the child items.
So itemIgnoresTransformation is not the solution.

[djasmine]

Anybody having any expertise around this problem, please share.

[SGaist]

From the looks of it, you would have to implement your own filtering of the transformations applied to your scene but since it's all handled on a lower level.

See the QGraphicsSceneBspTreeIndex.