From fd85076bb6ba9bb9511bfa37376f8685c68e1ba7 Mon Sep 17 00:00:00 2001 From: KIU Shueng Chuan Date: Fri, 8 Jan 2021 15:27:42 +0800 Subject: [PATCH] invert QTransform using adjoint() and determinant() --- pyqtgraph/functions.py | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/pyqtgraph/functions.py b/pyqtgraph/functions.py index fb716904..5cafae16 100644 --- a/pyqtgraph/functions.py +++ b/pyqtgraph/functions.py @@ -2324,26 +2324,32 @@ def isosurface(data, level): return vertexes, faces - +def _pinv_fallback(tr): + arr = np.array([tr.m11(), tr.m12(), tr.m13(), + tr.m21(), tr.m22(), tr.m23(), + tr.m31(), tr.m32(), tr.m33()]) + arr.shape = (3, 3) + pinv = np.linalg.pinv(arr) + return QtGui.QTransform(*pinv.ravel().tolist()) + + def invertQTransform(tr): """Return a QTransform that is the inverse of *tr*. - Rasises an exception if tr is not invertible. + A pseudo-inverse is returned if tr is not invertible. Note that this function is preferred over QTransform.inverted() due to bugs in that method. (specifically, Qt has floating-point precision issues when determining whether a matrix is invertible) """ try: - import numpy.linalg - arr = np.array([[tr.m11(), tr.m12(), tr.m13()], [tr.m21(), tr.m22(), tr.m23()], [tr.m31(), tr.m32(), tr.m33()]]) - inv = numpy.linalg.inv(arr) - return QtGui.QTransform(inv[0,0], inv[0,1], inv[0,2], inv[1,0], inv[1,1], inv[1,2], inv[2,0], inv[2,1]) - except ImportError: - inv = tr.inverted() - if inv[1] is False: - raise Exception("Transform is not invertible.") - return inv[0] + det = tr.determinant() + detr = 1.0 / det # let singular matrices raise ZeroDivisionError + inv = tr.adjoint() + inv *= detr + return inv + except ZeroDivisionError: + return _pinv_fallback(tr) def pseudoScatter(data, spacing=None, shuffle=True, bidir=False, method='exact'):