diff --git a/pyqtgraph/graphicsItems/GraphicsItem.py b/pyqtgraph/graphicsItems/GraphicsItem.py index bc49f48d..1a522446 100644 --- a/pyqtgraph/graphicsItems/GraphicsItem.py +++ b/pyqtgraph/graphicsItems/GraphicsItem.py @@ -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. """ _pixelVectorGlobalCache = LRUCache(100, 70) + _mapRectFromViewGlobalCache = LRUCache(100, 70) def __init__(self, register=None): if not hasattr(self, '_qtBaseClass'): @@ -367,8 +368,21 @@ class GraphicsItem(object): vt = self.viewTransform() if vt is 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): return Point(self._qtBaseClass.pos(self))