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# -*- coding: utf-8 -*-
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
from __future__ import division
from ..shaders import FunctionChain
from .base_transform import BaseTransform
from .linear import NullTransform
class ChainTransform(BaseTransform):
"""
BaseTransform subclass that performs a sequence of transformations in
order. Internally, this class uses shaders.FunctionChain to generate
its glsl_map and glsl_imap functions.
Arguments:
transforms : list of BaseTransform instances
See ``transforms`` property.
"""
glsl_map = None
glsl_imap = None
Linear = False
Orthogonal = False
NonScaling = False
Isometric = False
def __init__(self, *transforms):
super(ChainTransform, self).__init__()
self._transforms = []
self._simplified = None
self._null_transform = NullTransform()
nmap = self._null_transform.shader_map()
# ChainTransform does not have shader maps
self._shader_map = FunctionChain("transform_map_chain", [nmap])
self._shader_imap = FunctionChain("transform_imap_chain", [nmap])
# Set input transforms
trs = []
for tr in transforms:
if isinstance(tr, (tuple, list)):
trs.extend(tr)
else:
trs.append(tr)
self.transforms = trs
@property
def transforms(self):
""" The list of transform that make up the transform chain.
The order of transforms is given such that the last transform in the
list is the first to be invoked when mapping coordinates through
the chain.
For example, the following two mappings are equivalent::
# Map coordinates through individual transforms:
trans1 = STTransform(scale=(2, 3), translate=(0, 1))
trans2 = PolarTransform()
mapped = trans1.map(trans2.map(coords))
# Equivalent mapping through chain:
chain = ChainTransform([trans1, trans2])
mapped = chain.map(coords)
"""
return self._transforms
@transforms.setter
def transforms(self, tr):
if isinstance(tr, BaseTransform):
tr = [tr]
if not isinstance(tr, list):
raise TypeError("Transform chain must be a list")
# Avoid extra effort if we already have the correct chain
if len(tr) == len(self._transforms):
changed = False
for i in range(len(tr)):
if tr[i] is not self._transforms[i]:
changed = True
break
if not changed:
return
for t in self._transforms:
t.changed.disconnect(self._subtr_changed)
self._transforms = tr
for t in self._transforms:
t.changed.connect(self._subtr_changed)
self._rebuild_shaders()
self.update()
@property
def simplified(self):
"""A simplified representation of the same transformation.
"""
if self._simplified is None:
self._simplified = SimplifiedChainTransform(self)
return self._simplified
@property
def Linear(self):
b = True
for tr in self._transforms:
b &= tr.Linear
return b
@property
def Orthogonal(self):
b = True
for tr in self._transforms:
b &= tr.Orthogonal
return b
@property
def NonScaling(self):
b = True
for tr in self._transforms:
b &= tr.NonScaling
return b
@property
def Isometric(self):
b = True
for tr in self._transforms:
b &= tr.Isometric
return b
def map(self, coords):
"""Map coordinates
Parameters
----------
coords : array-like
Coordinates to map.
Returns
-------
coords : ndarray
Coordinates.
"""
for tr in reversed(self.transforms):
coords = tr.map(coords)
return coords
def imap(self, coords):
"""Inverse map coordinates
Parameters
----------
coords : array-like
Coordinates to inverse map.
Returns
-------
coords : ndarray
Coordinates.
"""
for tr in self.transforms:
coords = tr.imap(coords)
return coords
def shader_map(self):
return self._shader_map
def shader_imap(self):
return self._shader_imap
def _rebuild_shaders(self):
trs = self.transforms
if len(trs) == 0:
trs = [self._null_transform]
self._shader_map.functions = [tr.shader_map() for tr in reversed(trs)]
self._shader_imap.functions = [tr.shader_imap() for tr in trs]
def append(self, tr):
"""
Add a new transform to the end of this chain.
Parameters
----------
tr : instance of Transform
The transform to use.
"""
self.transforms.append(tr)
tr.changed.connect(self._subtr_changed)
self._rebuild_shaders()
self.update()
def prepend(self, tr):
"""
Add a new transform to the beginning of this chain.
Parameters
----------
tr : instance of Transform
The transform to use.
"""
self.transforms.insert(0, tr)
tr.changed.connect(self._subtr_changed)
self._rebuild_shaders()
self.update()
def _subtr_changed(self, ev):
"""One of the internal transforms changed; propagate the signal.
"""
self.update(ev)
def __setitem__(self, index, tr):
self._transforms[index].changed.disconnect(self._subtr_changed)
self._transforms[index] = tr
tr.changed.connect(self.subtr_changed)
self._rebuild_shaders()
self.update()
def __mul__(self, tr):
if isinstance(tr, ChainTransform):
trs = tr.transforms
else:
trs = [tr]
return ChainTransform(self.transforms+trs)
def __rmul__(self, tr):
if isinstance(tr, ChainTransform):
trs = tr.transforms
else:
trs = [tr]
return ChainTransform(trs+self.transforms)
def __str__(self):
names = [tr.__class__.__name__ for tr in self.transforms]
return "<ChainTransform [%s] at 0x%x>" % (", ".join(names), id(self))
def __repr__(self):
tr = ",\n ".join(map(repr, self.transforms))
return "<ChainTransform [%s] at 0x%x>" % (tr, id(self))
class SimplifiedChainTransform(ChainTransform):
def __init__(self, chain):
ChainTransform.__init__(self)
self._chain = chain
chain.changed.connect(self.source_changed)
self.source_changed(None)
def source_changed(self, event):
"""Generate a simplified chain by joining adjacent transforms.
"""
# bail out early if the chain is empty
transforms = self._chain.transforms[:]
if len(transforms) == 0:
self.transforms = []
return
# If the change signal comes from a transform that already appears in
# our simplified transform list, then there is no need to re-simplify.
if event is not None:
for source in event.sources[::-1]:
if source in self.transforms:
self.update(event)
return
# First flatten the chain by expanding all nested chains
new_chain = []
while len(transforms) > 0:
tr = transforms.pop(0)
if isinstance(tr, ChainTransform) and not tr.dynamic:
transforms = tr.transforms[:] + transforms
else:
new_chain.append(tr)
# Now combine together all compatible adjacent transforms
cont = True
tr = new_chain
while cont:
new_tr = [tr[0]]
cont = False
for t2 in tr[1:]:
t1 = new_tr[-1]
pr = t1 * t2
if (not t1.dynamic and not t2.dynamic and not
isinstance(pr, ChainTransform)):
cont = True
new_tr.pop()
new_tr.append(pr)
else:
new_tr.append(t2)
tr = new_tr
self.transforms = tr