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Merge pull request #1212 from erikmansson/fix-pv-cache

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Fix PixelVectors cache
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Luke Campagnola 2020-05-29 10:23:41 -07:00 committed by GitHub
commit 2d59ce8532
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1 changed files with 11 additions and 12 deletions
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23
pyqtgraph/graphicsItems/GraphicsItem.py
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@ -188,24 +188,23 @@ class GraphicsItem(object):
## (such as when looking at unix timestamps), we can get floating-point errors.
dt.setMatrix(dt.m11(), dt.m12(), 0, dt.m21(), dt.m22(), 0, 0, 0, 1)
if direction is None:
direction = QtCore.QPointF(1, 0)
elif direction.manhattanLength() == 0:
raise Exception("Cannot compute pixel length for 0-length vector.")
key = (dt.m11(), dt.m21(), dt.m12(), dt.m22(), direction.x(), direction.y())
## check local cache
if direction is None and dt == self._pixelVectorCache[0]:
if key == self._pixelVectorCache[0]:
return tuple(map(Point, self._pixelVectorCache[1])) ## return a *copy*
## check global cache
#key = (dt.m11(), dt.m21(), dt.m31(), dt.m12(), dt.m22(), dt.m32(), dt.m31(), dt.m32())
key = (dt.m11(), dt.m21(), dt.m12(), dt.m22())
pv = self._pixelVectorGlobalCache.get(key, None)
if direction is None and pv is not None:
self._pixelVectorCache = [dt, pv]
if pv is not None:
self._pixelVectorCache = [key, pv]
return tuple(map(Point,pv)) ## return a *copy*
if direction is None:
direction = QtCore.QPointF(1, 0)
if direction.manhattanLength() == 0:
raise Exception("Cannot compute pixel length for 0-length vector.")
## attempt to re-scale direction vector to fit within the precision of the coordinate system
## Here's the problem: we need to map the vector 'direction' from the item to the device, via transform 'dt'.
## In some extreme cases, this mapping can fail unless the length of 'direction' is cleverly chosen.