How to scale an object which inherit QGrahicsItem within it's parent QGraphicsItem

[christina123y]

You mean you don't want to make it possible to scale the child to such size that it would become larger than its parent, right? In that case reimplement QGraphicsItem::itemChange() for your item. There you can check the newly set size and compare it with the parent's. Finally you can return the new size for your item which will be bounded to the parent size.

First , I' m sorry, I' m a newer to this forum, and I don't know where to commit my question.

Yes,you are right, now when I use QGraphicsItem::scale or QGraphicsView::scale,that only scale the viewport ,that's not what I wanted.
And I don't catch your mean for i don't know how to use QGraphicsItem::itemChange() to signal it's size change to it's parent item. Should I use QGraphicsItem::ItemTransformHasChanged or QGraphicsItem::ItemPositionChange
as a parameter of QGraphicsItem::itemChange() ?
As I'm a newer to qt, so wish your reply again!
Thank you!
And could you provide me with source code on this ! Thank you very much!

[h123]

Hi christina123y,
Can please give some code example or snippet.
Thank you.

[spud]

Have you had a look at QWT

[wysota]

And I don't catch your mean for i don't know how to use QGraphicsItem::itemChange() to signal it's size change to it's parent item. Should I use QGraphicsItem::ItemTransformHasChanged or QGraphicsItem::ItemPositionChange
as a parameter of QGraphicsItem::itemChange() ?

Use ItemTransformChange so that you can return a new transformation.

And could you provide me with source code on this ! Thank you very much!

There is a nice example in the itemChange() documentation, only that it monitors the position and not the transformation of the item.

[christina123y]

Use ItemTransformChange so that you can return a new transformation.



There is a nice example in the itemChange() documentation, only that it monitors the position and not the transformation of the item.

Ok, Thanks!
I'll try my best to work out it!
Any question countered, I'll share in!