QGraphicsItemGroup

Inheritance diagram of PySide2.QtWidgets.QGraphicsItemGroup

Synopsis

Functions

Detailed Description

The PySide2.QtWidgets.QGraphicsItemGroup class provides a container that treats a group of items as a single item.

A PySide2.QtWidgets.QGraphicsItemGroup is a special type of compound item that treats itself and all its children as one item (i.e., all events and geometries for all children are merged together). It’s common to use item groups in presentation tools, when the user wants to group several smaller items into one big item in order to simplify moving and copying of items.

If all you want is to store items inside other items, you can use any PySide2.QtWidgets.QGraphicsItem directly by passing a suitable parent to PySide2.QtWidgets.QGraphicsItem.setParentItem() .

The PySide2.QtWidgets.QGraphicsItemGroup.boundingRect() function of PySide2.QtWidgets.QGraphicsItemGroup returns the bounding rectangle of all items in the item group. PySide2.QtWidgets.QGraphicsItemGroup ignores the ItemIgnoresTransformations flag on its children (i.e., with respect to the geometry of the group item, the children are treated as if they were transformable).

There are two ways to construct an item group. The easiest and most common approach is to pass a list of items (e.g., all selected items) to QGraphicsScene.createItemGroup() , which returns a new PySide2.QtWidgets.QGraphicsItemGroup item. The other approach is to manually construct a PySide2.QtWidgets.QGraphicsItemGroup item, add it to the scene calling QGraphicsScene.addItem() , and then add items to the group manually, one at a time by calling PySide2.QtWidgets.QGraphicsItemGroup.addToGroup() . To dismantle (“ungroup”) an item group, you can either call QGraphicsScene.destroyItemGroup() , or you can manually remove all items from the group by calling PySide2.QtWidgets.QGraphicsItemGroup.removeFromGroup() .

# Group all selected items together
group = scene.createItemGroup(scene.selecteditems())

# Destroy the group, and delete the group item
scene.destroyItemGroup(group)

The operation of adding and removing items preserves the items’ scene-relative position and transformation, as opposed to calling PySide2.QtWidgets.QGraphicsItem.setParentItem() , where only the child item’s parent-relative position and transformation are kept.

The addtoGroup() function reparents the target item to this item group, keeping the item’s position and transformation intact relative to the scene. Visually, this means that items added via PySide2.QtWidgets.QGraphicsItemGroup.addToGroup() will remain completely unchanged as a result of this operation, regardless of the item or the group’s current position or transformation; although the item’s position and matrix are likely to change.

The PySide2.QtWidgets.QGraphicsItemGroup.removeFromGroup() function has similar semantics to PySide2.QtWidgets.QGraphicsItem.setParentItem() ; it reparents the item to the parent item of the item group. As with PySide2.QtWidgets.QGraphicsItemGroup.addToGroup() , the item’s scene-relative position and transformation remain intact.

class PySide2.QtWidgets.QGraphicsItemGroup([parent=nullptr])
Parameters:parentPySide2.QtWidgets.QGraphicsItem

Constructs a PySide2.QtWidgets.QGraphicsItemGroup . parent is passed to PySide2.QtWidgets.QGraphicsItem ‘s constructor.

PySide2.QtWidgets.QGraphicsItemGroup.addToGroup(item)
Parameters:itemPySide2.QtWidgets.QGraphicsItem

Adds the given item and item’s child items to this item group. The item and child items will be reparented to this group, but its position and transformation relative to the scene will stay intact.

PySide2.QtWidgets.QGraphicsItemGroup.removeFromGroup(item)
Parameters:itemPySide2.QtWidgets.QGraphicsItem

Removes the specified item from this group. The item will be reparented to this group’s parent item, or to 0 if this group has no parent. Its position and transformation relative to the scene will stay intact.