75 lines
2.5 KiB
Python
75 lines
2.5 KiB
Python
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'''
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Dejitter
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========
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Prevent blob jittering.
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A problem that is often faced (esp. in optical MT setups) is that of
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jitterish BLOBs caused by bad camera characteristics. With this module
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you can get rid of that jitter. You just define a threshold
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`jitter_distance` in your config, and all touch movements that move
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the touch by less than the jitter distance are considered 'bad'
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movements caused by jitter and will be discarded.
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'''
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__all__ = ('InputPostprocDejitter', )
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from kivy.config import Config
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class InputPostprocDejitter(object):
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'''
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Get rid of jitterish BLOBs.
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Example::
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[postproc]
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jitter_distance = 0.004
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jitter_ignore_devices = mouse,mactouch
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:Configuration:
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`jitter_distance`: float
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A float in range 0-1.
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`jitter_ignore_devices`: string
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A comma-separated list of device identifiers that
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should not be processed by dejitter (because they're
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very precise already).
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'''
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def __init__(self):
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self.jitterdist = Config.getfloat('postproc', 'jitter_distance')
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ignore_devices = Config.get('postproc', 'jitter_ignore_devices')
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self.ignore_devices = ignore_devices.split(',')
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self.last_touches = {}
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def taxicab_distance(self, p, q):
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# Get the taxicab/manhattan/citiblock distance for efficiency reasons
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return abs(p[0] - q[0]) + abs(p[1] - q[1])
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def process(self, events):
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if not self.jitterdist:
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return events
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processed = []
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for etype, touch in events:
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if not touch.is_touch:
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continue
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if touch.device in self.ignore_devices:
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processed.append((etype, touch))
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continue
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if etype == 'begin':
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self.last_touches[touch.id] = touch.spos
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if etype == 'end':
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if touch.id in self.last_touches:
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del self.last_touches[touch.id]
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if etype != 'update':
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processed.append((etype, touch))
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continue
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# Check whether the touch moved more than the jitter distance
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last_spos = self.last_touches[touch.id]
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dist = self.taxicab_distance(last_spos, touch.spos)
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if dist > self.jitterdist:
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# Only if the touch has moved more than the jitter dist we take
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# it into account and dispatch it. Otherwise suppress it.
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self.last_touches[touch.id] = touch.spos
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processed.append((etype, touch))
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return processed
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