import weakref
from math import atan2, degrees
from ..functions import clip_scalar
from ..Qt import QtCore, QtWidgets
from . import ArrowItem
from .GraphicsObject import GraphicsObject
__all__ = ['CurvePoint', 'CurveArrow']
[docs]
class CurvePoint(GraphicsObject):
"""A GraphicsItem that sets its location to a point on a PlotCurveItem.
Also rotates to be tangent to the curve.
The position along the curve is a Qt property, and thus can be easily animated.
Note: This class does not display anything; see CurveArrow for an applied example
"""
[docs]
def __init__(self, curve, index=0, pos=None, rotate=True):
"""Position can be set either as an index referring to the sample number or
the position 0.0 - 1.0
If *rotate* is True, then the item rotates to match the tangent of the curve.
"""
GraphicsObject.__init__(self)
#QObjectWorkaround.__init__(self)
self._rotate = rotate
self.curve = weakref.ref(curve)
self.setParentItem(curve)
self.setProperty('position', 0.0)
self.setProperty('index', 0)
self.setFlags(self.flags() | self.GraphicsItemFlag.ItemHasNoContents)
if pos is not None:
self.setPos(pos)
else:
self.setIndex(index)
def setPos(self, pos):
self.setProperty('position', float(pos))## cannot use numpy types here, MUST be python float.
def setIndex(self, index):
self.setProperty('index', int(index)) ## cannot use numpy types here, MUST be python int.
def event(self, ev):
if not isinstance(ev, QtCore.QDynamicPropertyChangeEvent) or self.curve() is None:
return False
if ev.propertyName() == 'index':
index = self.property('index')
if 'QVariant' in repr(index):
index = index.toInt()[0]
elif ev.propertyName() == 'position':
index = None
else:
return False
(x, y) = self.curve().getData()
if index is None:
#print ev.propertyName(), self.property('position').toDouble()[0], self.property('position').typeName()
pos = self.property('position')
if 'QVariant' in repr(pos): ## need to support 2 APIs :(
pos = pos.toDouble()[0]
index = (len(x)-1) * clip_scalar(pos, 0.0, 1.0)
if index != int(index): ## interpolate floating-point values
i1 = int(index)
i2 = clip_scalar(i1+1, 0, len(x)-1)
s2 = index-i1
s1 = 1.0-s2
newPos = (x[i1]*s1+x[i2]*s2, y[i1]*s1+y[i2]*s2)
else:
index = int(index)
i1 = clip_scalar(index-1, 0, len(x)-1)
i2 = clip_scalar(index+1, 0, len(x)-1)
newPos = (x[index], y[index])
p1 = self.parentItem().mapToScene(QtCore.QPointF(x[i1], y[i1]))
p2 = self.parentItem().mapToScene(QtCore.QPointF(x[i2], y[i2]))
rads = atan2(p2.y()-p1.y(), p2.x()-p1.x()) ## returns radians
self.resetTransform()
if self._rotate:
self.setRotation(180 + degrees(rads))
QtWidgets.QGraphicsItem.setPos(self, *newPos)
return True
def boundingRect(self):
return QtCore.QRectF()
def paint(self, *args):
pass
def makeAnimation(self, prop='position', start=0.0, end=1.0, duration=10000, loop=1):
# In Python 3, a bytes object needs to be used as a property name in
# QPropertyAnimation. PyQt stopped automatically encoding a str when a
# QByteArray was expected in v5.5 (see qbytearray.sip).
if not isinstance(prop, bytes):
prop = prop.encode('latin-1')
anim = QtCore.QPropertyAnimation(self, prop)
anim.setDuration(duration)
anim.setStartValue(start)
anim.setEndValue(end)
anim.setLoopCount(loop)
return anim
[docs]
class CurveArrow(CurvePoint):
"""Provides an arrow that points to any specific sample on a PlotCurveItem.
Provides properties that can be animated."""
[docs]
def __init__(self, curve, index=0, pos=None, **opts):
CurvePoint.__init__(self, curve, index=index, pos=pos)
if opts.get('pxMode', True):
opts['pxMode'] = False
self.setFlags(self.flags() | self.GraphicsItemFlag.ItemIgnoresTransformations)
opts['angle'] = 0
self.arrow = ArrowItem.ArrowItem(**opts)
self.arrow.setParentItem(self)
def setStyle(self, **opts):
return self.arrow.setStyle(**opts)
