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Add cache for mapRectFromView

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This commit is contained in:
Erik Månsson 2020-05-30 16:25:43 +02:00
parent 3f6424cc57
commit 55e1f2c520
1 changed files with 16 additions and 2 deletions
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18
pyqtgraph/graphicsItems/GraphicsItem.py
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@ -19,6 +19,7 @@ class GraphicsItem(object):
The GraphicsView system places a lot of emphasis on the notion that the graphics within the scene should be device independent--you should be able to take the same graphics and display them on screens of different resolutions, printers, export to SVG, etc. This is nice in principle, but causes me a lot of headache in practice. It means that I have to circumvent all the device-independent expectations any time I want to operate in pixel coordinates rather than arbitrary scene coordinates. A lot of the code in GraphicsItem is devoted to this task--keeping track of view widgets and device transforms, computing the size and shape of a pixel in local item coordinates, etc. Note that in item coordinates, a pixel does not have to be square or even rectangular, so just asking how to increase a bounding rect by 2px can be a rather complex task. The GraphicsView system places a lot of emphasis on the notion that the graphics within the scene should be device independent--you should be able to take the same graphics and display them on screens of different resolutions, printers, export to SVG, etc. This is nice in principle, but causes me a lot of headache in practice. It means that I have to circumvent all the device-independent expectations any time I want to operate in pixel coordinates rather than arbitrary scene coordinates. A lot of the code in GraphicsItem is devoted to this task--keeping track of view widgets and device transforms, computing the size and shape of a pixel in local item coordinates, etc. Note that in item coordinates, a pixel does not have to be square or even rectangular, so just asking how to increase a bounding rect by 2px can be a rather complex task.
""" """
_pixelVectorGlobalCache = LRUCache(100, 70) _pixelVectorGlobalCache = LRUCache(100, 70)
_mapRectFromViewGlobalCache = LRUCache(100, 70)
def __init__(self, register=None): def __init__(self, register=None):
if not hasattr(self, '_qtBaseClass'): if not hasattr(self, '_qtBaseClass'):
@ -367,8 +368,21 @@ class GraphicsItem(object):
vt = self.viewTransform() vt = self.viewTransform()
if vt is None: if vt is None:
return None return None
vt = fn.invertQTransform(vt)
return vt.mapRect(obj) cache = self._mapRectFromViewGlobalCache
k = (
vt.m11(), vt.m12(), vt.m13(),
vt.m21(), vt.m22(), vt.m23(),
vt.m31(), vt.m32(), vt.m33(),
)
try:
inv_vt = cache[k]
except KeyError:
inv_vt = fn.invertQTransform(vt)
cache[k] = inv_vt
return inv_vt.mapRect(obj)
def pos(self): def pos(self):
return Point(self._qtBaseClass.pos(self)) return Point(self._qtBaseClass.pos(self))