63 lines
2.1 KiB
Python
63 lines
2.1 KiB
Python
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from ..Qt import QtGui, QtCore
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from ..Point import Point
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class GraphicsWidgetAnchor:
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"""
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Class used to allow GraphicsWidgets to anchor to a specific position on their
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parent.
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"""
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def __init__(self):
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self.__parent = None
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self.__parentAnchor = None
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self.__itemAnchor = None
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self.__offset = (0,0)
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if hasattr(self, 'geometryChanged'):
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self.geometryChanged.connect(self.__geometryChanged)
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def anchor(self, itemPos, parentPos, offset=(0,0)):
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"""
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Anchors the item at its local itemPos to the item's parent at parentPos.
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Both positions are expressed in values relative to the size of the item or parent;
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a value of 0 indicates left or top edge, while 1 indicates right or bottom edge.
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Optionally, offset may be specified to introduce an absolute offset.
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Example: anchor a box such that its upper-right corner is fixed 10px left
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and 10px down from its parent's upper-right corner::
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box.anchor(itemPos=(1,0), parentPos=(1,0), offset=(-10,10))
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"""
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parent = self.parentItem()
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if parent is None:
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raise Exception("Cannot anchor; parent is not set.")
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if self.__parent is not parent:
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if self.__parent is not None:
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self.__parent.geometryChanged.disconnect(self.__geometryChanged)
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self.__parent = parent
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parent.geometryChanged.connect(self.__geometryChanged)
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self.__itemAnchor = itemPos
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self.__parentAnchor = parentPos
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self.__offset = offset
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self.__geometryChanged()
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def __geometryChanged(self):
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if self.__parent is None:
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return
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if self.__itemAnchor is None:
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return
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o = self.mapToParent(Point(0,0))
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a = self.boundingRect().bottomRight() * Point(self.__itemAnchor)
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a = self.mapToParent(a)
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p = self.__parent.boundingRect().bottomRight() * Point(self.__parentAnchor)
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off = Point(self.__offset)
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pos = p + (o-a) + off
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self.setPos(pos)
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