File: chain.py

package info (click to toggle)
python-vispy 0.6.6-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 21,240 kB
  • sloc: python: 57,407; javascript: 6,810; makefile: 63; sh: 5
file content (303 lines) | stat: -rw-r--r-- 9,021 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
# -*- 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))

    def __del__(self):
        # remove all the children transforms from our callback, since we are
        # being deleted.  (But we do *not* want to remove children from other
        # callbacks)
        for t in self._transforms:
            t.changed.disconnect(self._subtr_changed)
        self.changed.disconnect()


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